Google
 

Trailing-Edge - PDP-10 Archives - decuslib20-03 - decus/20-0078/doc/simlh3.man
There is 1 other file named simlh3.man in the archive. Click here to see a list.


Swedish National Defense Research Institute       FOA Report
Department of Planning and Operations Research    C10045-M3(E5)
S-10450 Stockholm                                 July 1978

DECsystem-10 SIMULA Language Handbook Part III
==============================================

   (The DECsystem-10 SIMULA Utility Program Library)

BY Stefan Arnborg, Lars Enderin, Mats Ohlin, Stephan Oldgren and
   Jacob Palme.


ABSTRACT

   The DECsystem-10 SIMULA Language Handbook contains the
   information necessary for an applications programmer who
   intends to use SIMULA on a DECsystem-10 computer.

   Part I describes the SIMULA programming language.
   Part II contains special information for DECsystem-10.
   Part III describes the utility program library, which
   includes:

 > The SAFEIO package for safe conversational terminal interface.

 > Utility routines for inserting a help facility into the
   conversational terminal communication, where the appropriate
   help message at each point in the program can be selected from
   a file containing several messages.

 > Routines for accessing date, time etc.

 > Routines to allow writing real-time programs in SIMULA (e.g.
   programs which can communicate simultaneously with more than
   one user terminal.) These routines do not work with
   DECsystem-20.

 > Routines for binary (un-formatted) I/O.

 > Routines for record-oriented I/O.

 > Routines for file handling.

 > A utility package of routines for character string (TEXT)
   handling, with routines for searching, splitting,
   concatenating, hashing etc.

 > Routines for in-core sorting and summation.

   This document reflects the software as of version 4 of the
   DECsystem-10 SIMULA system.

   Last update 1978-05-23.
DECsystem-10 SIMULA Language Handbook, part III            Page 2


SEARCH KEY

     Computer, Programming, Programming Language, SIMULA,
     DECsystem-10, Digital Equipment, Algol 60, Fortran, Program
     library, file handling, input/output, conversational
     programming, real time, error handling, string handling,
     character handling, text handling, sorting.

CONDITIONS OF RELEASE

     The information in this document is subject to change
     without notice.  The Swedish National Defence Research
     Institute assumes no responsibility for any errors that may
     appear in this document, in the programs described therein
     or in the SIMULA system itself.  No promise is made to
     implement any of these programs, especially not those marked
     "NOT READY".

     This document and the software described in it is furnished
     to the user for use on a DECsystem-10 computer system and
     may be copied only for use on such systems, except as may
     otherwise be provided in writing by the Swedish National
     Defence Research Institute.

ACKNOWLEDGEMENT

     Part of section 4.1 has been adapted from the similar text
     for the IBM 360/370 SIMULA System, written by Karel Babcicky
     at the Norwegian Computing Center.

     Copyright 1976, 1977 by The Swedish National Defense
     Research Institute and (partly) The Norwegian Computing
     Center.

SOME OF THE PROCEDURES ARE NOT YET WRITTEN

     This preliminary version of part III of the handbook
     includes some procedures which have not yet been
     implemented.  Their descriptions are only proposals.  Some
     of these procedures may eventually be implemented in a
     different fashion, if at all.

     These procedures are marked [NOT READY] in section 0.2 but
     they are not always marked [NOT READY] in the following
     chapters.  Always refer to section 0.2 to check if a
     procedure is available.
DECsystem-10 SIMULA Language Handbook, part III            Page 3


     TABLE OF CONTENTS


     0.   INTRODUCTION

          0.1  HOW TO GET ACCESS TO THE LIBRARY

          0.2  SUMMARY LIST OF ROUTINES


     1.   UTILITY PACKAGES

          1.1  APPLICATION PACKAGES

          1.2  DEMONSTRATION PROGRAMS

     2.   SIMULA SOURCE PROGRAM CONVERSION PROGRAMS

     3.   DIRECTFILE HANDLING PROGRAMS

     4.   PROCEDURES NOT WRITEABLE IN SIMULA

          4.1  TIME AND DATE

          4.2  BASIC ASSEMBLY PROCEDURES FOR REAL TIME

          4.3  INPUT/OUTPUT

               4.3.1 ASCII-FORMATTED I/O

               4.3.2 UNFORMATTED (BINARY) I/O

               4.3.3 FILE HANDLING

          4.4  CONTROLLED ERROR HANDLING

          4.5  SCHEDULING AND JOB CONTROL

          4.6  MEMORY HANDLING
               [These facilities are not yet ready.]

               4.6.1 PRIMARY MEMORY HANDLING

               4.6.2 VIRTUAL MEMORY HANDLING (OR OVERLAY
                     FACILITY)

          4.7  ENVIRONMENT ENQUIRY

          4.8  PACKING INTO PARTS OF WORDS
DECsystem-10 SIMULA Language Handbook, part III            Page 4


               4.8.1 PACK AND UNPACK, PARAMETERS

               4.8.2 PACK AND UNPACK, ERROR HANDLING

               4.8.3 PACK AND UNPACK, METHODS OF PACKING

               4.8.4 PACK AND UNPACK, METHODS OF UNPACKING

               4.8.5 PACK AND UNPACK, EXAMPLES

          4.9 MIN AND MAX


     5.   ROUTINES WRITEABLE IN SIMULA.

          5.1  PARTITIONING OF TEXTS

          5.2  SEARCHING AND TESTING OF TEXTS

          5.3  OPERATIONS ON TEXTS

          5.4  INPUT/OUTPUT

          5.5  SORTING AND SUMMATION ETC.

          5.6  RANDOM NUMBER GENERATION ETC.

          5.7  SIMULA VERSIONS OF SYSTEM CLASSES


     6.   SWEDISH LANGUAGE TEXT HANDLING AND INPUT/OUTPUT

     7.   UTILITIES SPECIFIC TO DECSYSTEM-10

     APPENDIX A - REALTIME - A SCHEDULER FOR TERMINAL PROCESSES

     APPENDIX B - CONTROLLED ERROR HANDLING

     APPENDIX C - INDEX
DECsystem-10 SIMULA Language Handbook, part III            Page 5


0.  INTRODUCTION
    ------------

     The intention is to include in this document descriptions of
     utility programs, classes and procedures of general interest
     to users of SIMULA on the DECsystem-10.

     Examples:
   > Programs for editing and generating SIMULA source programs.
   > Useful program packages written in SIMULA such as data base
     packages, graphic packages, conversational I/O packages.
   > Useful MACRO 10 programs to be called from SIMULA, e.g. for
     object and binary I/O, access to monitor facilities like the
     clock.

     The programs described here will be distributed to
     DECsystem-10 users through the DECUS library, either as
     separate programs or on the SIMULA distribution tape.

     Anyone who has submitted a program to the DECUS library,
     such that the program is also suitable for inclusion in the
     SIMULA program library, is invited to send us a copy of the
     program and its documentation.  If we accept the program, we
     will include its description in future editions of this
     handbook.  Contributions in the form of procedures and
     classes of general interest are also welcome, preferably in
     machine-readable form with full documentation.  We may
     modify the code to better fit the rest of the system, if you
     allow us to do so.  We cannot promise to include your
     contributions, however.


0.1 HOW TO GET ACCESS TO THE LIBRARY

     Most of the procedures and classes described in this
     document are available in the library files LIBSIM.ATR and
     LIBSIM.REL.  These files should normally be available on the
     SYS: area on your computer, but you can also keep them on
     your own disk area.  Main programs to be executed directly
     are available as separate .SAV (.EXE) files, not in the
     LIBSIM files.

     Library procedures will be available to your program if you
     declare them as external at the beginning of your program,
     e.g:

     EXTERNAL CLASS safeio;
     EXTERNAL INTEGER PROCEDURE hash;

     You need not mention any explicit filename if you are using
     LIBSIM on the SYS area or on your own area.  An external
     declaration in a separately compiled segment (module) must
DECsystem-10 SIMULA Language Handbook, part III            Page 6


     be repeated in all dependent modules including the main
     program.  Please note that when you use modules in LIBSIM
     that are coded in SIMULA you will sometimes have to
     explicitly declare other LIBSIM routines.  The compiler will
     duly tell the user which declarations are missing.

     If you want to use other libraries, see the DECsystem-10
     SIMULA Language Handbook part II chapter 7.1.1.

     Normally, when you load your programs with the LOAD, EXECUTE
     or DEBUG commands of DECsystem-10, you need not mention the
     names of any separately compiled classes or procedures.
     Just write:

     .EXECUTE myprog

     if your program has the name myprog.  Any external classes
     or procedures declared as such inside myprog will
     automatically be loaded.

     If you cannot find the necessary .SIM, .REL, .ATR, .HLP,
     .MAN or .DOC files on the SYS:, HLP: or DOC: areas on your
     computer, they may still be found on the SIMULA distribution
     tape.  REL and ATR files for separately compiled procedures
     or classes can be found in the library LIBSIM (.ATR and
     .REL) on the SYS: area.

     For procedures written in MACRO-10, there is usually no
     separate .SIM specification file.  Instead, the .MAC file is
     written such that when you compile it with the SIMULA
     compiler, the necessary .ATR file is produced.

     In addition to the utilities listed below, a SIMULA
     programmer has access to a number of built-in standard
     procedures.  These are described in appendix B to the
     DECsystem-10 SIMULA Language Handbook part I.

     The procedures, classes and main programs listed below are
     described in this document.
DECsystem-10 SIMULA Language Handbook, part III            Page 7
0.2 SUMMARY LIST OF ROUTINES


0.2 SUMMARY LIST OF ROUTINES

The first column for each program indicates type of result for
function procedures, K for separately compiled classes, M for
main programs (not in LIBSIM).  The following letters indicate
parameter types.

Letter codes in this list:

..=repetition of parameter, R=REAL, L=LONG REAL, I=INTEGER,
C=CHARACTER, T=TEXT, X=REF, B=BOOLEAN, G=LABEL, a=ARRAY,
P=PROCEDURE, K=CLASS, M=MAIN PROGRAM.

An asterisk (*) indicates efficient, MACRO-10 coded procedure.

1. UTILITY PACKAGES

1.1 APPLICATION PACKAGES

K T,T     SAFEIO            Safe conversational terminal I/O.
                            See SAFEIO.HLP and SAFEIO.MAN
K T       SAFEI             SAFEIO without file handling
                            facilities
K         SAFMIN            Small, simplified version of SAFEI
K T,T     SIMEIO            Same as SAFEIO but prefixed with
                            SIMULATION
K T       SIMEI             Same as SAFEI but prefixed with
                            SIMULATION
K         SIMMIN            Same as SAFMIN but prefixed with
                            SIMULATION
K         SIMDBM            CODASYL DBTG type DBMS system.
                            Consists of the external classes
                            SIMDBM (DBMMIN), DBMSET and the main
                            programs DBDUMP, DBLOAD, DBSORT,
                            FETCH, HMAKE, TRANSF, LOAD, DIRED,
                            SPEC, PREP and PREP2
K I,I     STORE             Simple text-oriented DBMS
K         SELECT            Boolean condition searching TEXT or
                            FILE
K I,I,I   GPSSS             GPSS-like queue simulation package
K I,I,I,C,I GPSSST          GPSSS with more automatic trace
                            facilities
K         FIGURE            Plot package for Tektronix plotter.
                            GRAPHI, COSYS, COSYSF and RUBOUT are
                            also part of this package.  See
                            FIGURE.HLP
K I,I,X,B,I VISTA           Full control of alphanumeric display
                            screen, e.g.  to produce moving
                            pictures
K I,I,X,B,I FORM            Form fill in data entry, subclass of
                            VISTA
DECsystem-10 SIMULA Language Handbook, part III            Page 8
0.2 SUMMARY LIST OF ROUTINES


P I,I,I,T GETVIS            Terminal type input for VISTA
K T       DAHELP            Gives user help message when running
                            SIMULA program.  Uses direct-access
                            file to store help messages.  See
                            DAHELP.HLP
B T,T,I,I SQHELP            Gives user help message when running
                            SIMULA program.  Uses sequential file
                            to store help messages

1.2 DEMONSTRATION PROGRAMS
M         (Not listed here)

2. SIMULA SOURCE CODE CONVERSION PROGRAMS

                            [These are main programs, and thus
                            not placed in LIBSIM]

M         SIMED             Prettyprinting, cleaner layout,
                            indentation of BEGIN-END, no semantic
                            change of program
M         SIMSTR            [NOT READY] Automatic structure
                            abstract of source program
M         SIMEXP            Combines separately compiled modules
                            into one module
M         SIMIBM            Conversion to IBM Simula
M         IBMSIM            Conversion from IBM Simula
M         CDCSIM            Conversion from CDC Simula
M         FQCRED            Adds frequency count statements to a
                            SIMULA program
M         FQCLST            Edits SIMULA source program with
                            frequency measurements

3. DIRECTFILE HANDLING PROGRAMS

M         DIRED             Edits a directfile
M         MAKEDF            Converts sequential files to
                            directfiles and vice versa
M         FETCH             General-purpose SIMDBM Data Base
                            Manipulator
M         MAKHLP            Creates help file for use with DAHELP


4. PROCEDURES NOT WRITEABLE IN SIMULA
DECsystem-10 SIMULA Language Handbook, part III            Page 9
0.2 SUMMARY LIST OF ROUTINES


                            4.1 TIME AND DATE

T         TODAY(*)          Gives TEXT with date:  yyyy-mm-dd
I         DAYNO             Number of this day in current year
T         DAYTIME(*)        Gives TEXT with hh:mm:ss
R         CLOCKTIME(*)      Gives REAL with time of day in
                            seconds
R         CPTIME(*)         Gives LONG REAL with CPU time in
                            seconds
? ?       TIMELIMIT         [NOT READY] Sets time limit for
                            current execution

                            4.2 REAL TIME

B X       INPUTCHECK(*)     Anything to read on file X?
P R       SLEEP(*)          Delays execution for R real seconds
I Xa,R    INPUTWAIT(*)      Sleeps until anything to read
K         REALTIME          Scheduler for terminal processes

                            4.3 INPUT/OUTPUT

I X       LINECOUNT(*)      Returns LINESPERPAGE setting
I X       FILENAME(*)       Gives TEXT with FILE object
                            generation parameter
C         GETCH(*)          Inputs character, will not wait for
                            carriage return (input from
                            controlling terminal only)
B R       TTYCHECK(*)       Checks if a character has been typed
                            in at the controlling terminal
P X,C,I   OUTCHR(*)         Outputs character bypassing image
P X       FORCEOUT(*)       Terminal output buffer to terminal
C X       INSINGLECHAR(*)   Inputs character, does not wait for
                            carriage return (Input from disk or
                            controlling TTY)
C X       INSNGL(*)         As INSINGLECHAR, but line mode (waits
                            for break character)
P ILRCPa..  READ(*)         Reads many values in standard format
P ILRCTPa..  WRITE(*)       Writes many values in standard format
I X,RLICBTXa..  OUTPUT(*)   Binary output
I X,RLICBTXa..  INPUT(*)    Binary input
I RLICBTXa..  PUTSIZE(*)    How much will OUTPUT write?
B X,I     BYPASS(*)         [NOT READY] Bypass I characters in a
                            file
B X,LRIC  LOOK(*)           [NOT READY] Binary one-word lookahead
                            in input
B T       SCRATCHFILE(*)    Deletes file on secondary storage
X T       FINDINFILE(*)     NEW INFILE, but no error if file is
                            not available
X T,B     FINDDIRECTFILE(*) NEW DIRECTFILE, NONE if not available
                            for requested access
X T       FINDOUTFILE(*)    NEW OUTFILE, NONE if write protected
DECsystem-10 SIMULA Language Handbook, part III           Page 10
0.2 SUMMARY LIST OF ROUTINES


X T       FINDPRINTFILE(*)  NEW PRINTFILE, NONE if write
                            protected
I X       LASTLOC(*)        Highest written line in a DIRECTFILE
I X       MAXLOC(*)         [NOT READY] Highest writeable line in
                            a DIRECTFILE
P X       CLOSEOPEN(*)      [NOT READY] Close and immediately
                            open a file
B X       DOTYPEOUT(*)      Resets CTRL-O bit to resume terminal
                            output.  TRUE if file is a terminal
                            and the operation was successful.

                            4.4 CONTROLLED ERROR HANDLING

P B       ENTERDEBUG(*)     Transfers to SIMULA debugging system
P T       ABORT(*)          User program generated error
                            interrupt
P I       FORSIM(*)         Traps I/O calls from FORTRAN external
                            procedures

                            4.5 SCHEDULING AND JOB CONTROL

P B       SUBMIT(*)         [NOT READY] Enter file into input
                            batch stream
P T,I     RUN(*)            Runs a new program under current job
I T,B     SAVE(*)           Saves current main memory on a file
P T       RESTORE(*)        Resumes execution from save file
P I       FREEZE(*)         Exits to monitor, ready for SAVE
P I       EXIT(*)           Exits directly to monitor (I=0),
                            after closing files (I=1), to SIMDDT
                            (I=2).

                            4.6.1 PRIMARY MEMORY HANDLING

I I       FREEBITS(*)       [NOT READY] Forces garbage
                            collection, return maximal free area
                            size

                            4.6.2 VIRTUAL MEMORY CONTROL

B I       COREGUIDE(*)      [NOT READY] Sets physical guideline
B I       CORELIMIT(*)      [NOT READY] Sets physical limit
P XP..    SWAP(*)           [NOT READY] Swaps out given module
                            from main store
DECsystem-10 SIMULA Language Handbook, part III           Page 11
0.2 SUMMARY LIST OF ROUTINES


                            4.7 ENVIRONMENT ENQUIRY

I         MAXINT(*)         Returns largest positive INTEGER
R         MAXREAL(*)        Returns largest positive REAL
R         MINREAL(*)        [NOT READY] Returns smallest positive
                            REAL
L LR,LR   APPROX(*)         [NOT READY] Returns integer value
                            corresponding to numbers of bits
                            differing in two arguments
T         IMPLEMENTATION(*) [NOT READY] CPU manufacturer and
                            model
T         LOGINFO(*)        [NOT READY] User and job id
I a       DIMENSIONS(*)     [NOT READY] Number of dimensions
                            (subscripts) of ARRAYs

                            4.8 PACKING INTO PARTS OF WORDS(*)

B IRLa,I,IRLCBTa,I,.. PACK  Packs many variables of varying type
B IRLa,I,IRLCBTa,I,.. UNPACK Reverse of pack

                            4.9 MIN AND MAX

I I1,I2   IMAX(*)           Max(I1,I2)
I I1,I2   IMIN(*)           Min(I1,I2)
R R1,R2   RMAX(*)           Max(R1,R2)
R R1,R2   RMIN(*)           Min(R1,R2)
L L1,L2   LMAX(*)           Max(L1,L2)
L L1,L2   LMIN(*)           Min(L1,L2)


5. PROCEDURES WRITEABLE IN SIMULA

                            5.1 PARTITIONING OF TEXTS

T T       REST(*)           Subtext after POS
T T       FRONT(*)          Subtext before POS
T T,I     FROM(*)           Subtext after pos=I in T
T T,I     UPTO(*)           Subtext before pos=I in T
T T       FRONTSTRIP(*)     Subtext without leading blanks
T T       GETITEM(*)        Subtext = next identifier, number or
                            delimiter after POS
T X       INITEM(*)         GETITEM on INFILE [NOT READY FOR
                            DIRECTFILES] or DIRECTFILE
C T,I     FETCHAR(*)        Returns T.Sub(I,1).Getchar, null if I
                            out of range
P T,I,C   DEPCHAR(*)        T.Sub(I,1).Putchar(C), no action if
                            out of range.
T T,I1,I2 TSUB(*)           T.Sub(I1,I2), NOTEXT where Sub gives
                            error
DECsystem-10 SIMULA Language Handbook, part III           Page 12
0.2 SUMMARY LIST OF ROUTINES


                            5.2 SEARCHING AND TESTING OF TEXTS

T T,C     SCANTO(*)         Next occurrence of C in T
T C       SKIP(*)           Skips string of characters = C from
                            T.Pos
B T1,T2   FRONTCOMPARE(*)   Does rest of T1 begin with subtext =
                            T2?
B T1,T2   UPCOMPARE(*)      Same as FRONTCOMPARE, but upper and
                            lower case letters are regarded as
                            equal
I T1,T2   SEARCH(*)         Finds first subtext = T2 from T1.Pos
I T       GETTYPE           [NOT READY] Does a TEXT contain REAL,
                            INTEGER, IDENTIFIER or what ITEM?
I T       CHECKREAL(*)      Checks if GETREAL can be performed
I T       CHECKINT(*)       Checks if GETINT can be performed
I T       CHECKFRAC(*)      Checks if GETFRAC can be performed
I T,I     HASH              Computes hash value from text in
                            interval [0:I-1]
C T1,T2   FINDTRIGGER(*)    Next occurrence of any character of
                            T2 in T1
B T,I,Ta,I MENU             Searches for unambiguous text in a
                            text array
B T,Ta,I,I,I LOOKUP         Performs binary search in sorted text
                            array

                            5.3 OPERATIONS ON TEXTS

T T,T     CONC2(*)          Concatenation of TEXTs, two parms
T T..     CONC(*)           Concatenation of variable no. of
                            TEXTs
B T1,T2   PUTTEXT(*)        Copies value of T2 starting at T1.Pos
T T       UPCASE(*)         Converts to upper case
T T       LOWCASE(*)        Converts to lower case
T C,I     MAKETEXT(*)       NEW text, all I characters equal to C
T T,C     COMPRESS(*)       Removes given character from text
I T       STARTPOS(*)       Returns starting position for a
                            (sub)text
B T1,T2,T3 CHANGE           Replaces first substring of T1 = T2,
                            if any, with T3.  Search starts at
                            T1.Pos
L T       SCANREAL(*)       GETREAL, safe from bad data, starts
                            at T.Pos
I T       SCANINT(*)        GETINT, safe from bad data, starts at
                            T.Pos
I T       SCANFRAC(*)       GETFRAC, safe from bad data, starts
                            at T.Pos
I T,Ra,I  GETARRAY          [NOT READY] Reads from a text real
                            values into a REAL ARRAY
I T,Ia,I  GETINTARRAY       [NOT READY] Ditto INTEGER ARRAY
I T,Ra,I  GETLONGARRAY      [NOT READY] Ditto LONG REAL ARRAY
T T,R,C,I PUTTIME           Edits a number in TIME format
DECsystem-10 SIMULA Language Handbook, part III           Page 13
0.2 SUMMARY LIST OF ROUTINES


T T,R     PUTFLOAT          Edits a number using minimum no. of
                            characters
T I,I     RADIX             Edits 2nd parm to an item in 1st parm
                            base.
I I,T     GETRADIX          Deedits an item(T) in base I to an
                            integer value.
P T,T,T,T SPLIT             Splits a text at given delimiter
                            string
I T,T,Ta,I SPLITA           Splits a text and stores the parts in
                            a text array
I T,C,Ta,I SPLITC           Same as SPLITA but with character
                            delimiter
I T,I,Ta,Ta SCAN            Identifies keywords in a command
                            string.
I T,I,Ta,Ta SSCAN           Version of SCAN used by GETVIS.
K I       DECOM             (Subclass to SAFMIN) Interprets input
                            command of the format
                            outfil.ext/switch1/switch2...
                            =infil.ext/switch3/switch4...
I Ta      ARRLGD(*) Total length of texts in Ta + number of
                            elements.  Used in SIMDBM.
P Ta,T,C  ARRTXT(*) Put all texts of Ta in T, with delimiter = C.
                            Used in SIMDBM.

                            5.4 INPUT/OUTPUT

C X       LOOKAHEAD(*)      Next non-blank character readable by
                            INCHAR
P T,X     OUTLINE(*)        [NOT READY] Output TEXT on new
                            line(s), TEXT may be longer than
                            image
P T,X     BREAKOUTLINE(*)   [NOT READY] Output TEXT on same line,
                            TEXT may be longer than image
T T,X     INLINE            Types out a prompting question and
                            copies an infile image (stripped)
T T,T,T,B,T,T REQUEST       Sophisticated INLINE with input
                            check, help etc.
P X,R,C,I OUTTIME           Prints simulated time in hh:mm:ss.cc
                            format
P ..      HISTP             Prints histogram of Ia on file X

                            5.5 SORTING AND SUMMATION ETC.

I R       ILOG              Returns integer part of
                            10LOG(Abs(R))+1;  if R = 0 return 0.
                            I.e.  Number of integer digits if
                            Abs(R) >= 1 else number of leading
                            zeros after decimal point
I Ia,I    ISUM              Returns sum of an integer array
L La,I    LSUM              Returns sum of long real array
                            (almost) preserving precision
DECsystem-10 SIMULA Language Handbook, part III           Page 14
0.2 SUMMARY LIST OF ROUTINES


R Ra,I    RSUM              Returns sum of real array
R R,R,Ra,I SIGMA2           Returns variance, mean value of a
                            real array
P R,R,I,R SIGMEAN           Returns current variance and mean
                            value including new observation
P "x"a,I  SORTxy            Sorts a given array in ascending or
                            descending order.
                            x = T(ext), R(eal), I(nteger) or
                            L(ong real)
                            y = A(scending), D(escending) order
P Ia,I1,I2,I3 SORTDN        Sorts slice Ia[1:2,I1:I1-1+N] with
                            respect to either or both integers in
                            each row.
R R,R,I   SCALESTEP         Adjusts approx.  max and min for
                            diagram design
B Ia,I,I,I,B IASHIFT(*)     Moves part of an integer array
                            leftward.

                            5.6 RANDOM NUMBER GENERATION ETC.

P Ia,I,I,I SCRAMBLE         Random permutation of array
C Ia,N    PERGEN            Systematic generation of permutations
R R,R     RANDOM(*)         Random generator of random number
                            series start numbers
I         UNIQUE            Unique number to be used e.g.  as
                            start random number (seed)
I I1,I2   NEXTRANDOM(*)     Returns the I1:th successor to random
                            seed I2

                            5.7 SIMULA VERSIONS OF SYSTEM CLASSES

K         ZIMSET            SIMULA tracing version of SIMSET
K         ZIMULATION        SIMULA tracing version of SIMULATION


6.   SWEDISH LANGUAGE TEXT PROCESSING AND INPUT/OUTPUT

B C       BOKSTAV(*)        Swedish version of Letter
T X       INORD(*)          Swedish version of INITEM

T T       LITENBOKSTAV(*)   Swedish version of LOWCASE

B T,I,Ta,I MENY             Swedish version of MENU

T T       STORBOKSTAV(*)    Swedish version of UPCASE
T T       TAGORD(*)         Swedish version of GETITEM

I T       TAGTYP            [NOT READY] Swedish version of
                            GETTYPE
DECsystem-10 SIMULA Language Handbook, part III           Page 15
0.2 SUMMARY LIST OF ROUTINES


7.   UTILITIES SPECIFIC TO DECSYSTEM-10

I I1,I2   ADJPTR(*)         Byte pointer I1 adjusted by I2 bytes

I I1,I2   ANDINT(*)         Bitwise AND function
K         ATRSTR            ATR file structure
I I1,I2,I3 BITFIELD(*)      Returns a bit field within I1
                            starting at bit I2 (0-35) with length
                            Abs(I3) (1-36) (I3 negative gives
                            sign extension)
B I1,I2   BITGET(*)         BITGET:=I1.bit(36-I2)=1
P I1,I2,B BITPUT(*)         I1.bit(36-I2):=IF B THEN 1 ELSE 0
I I1,I2,I3 BOOLFUNC(*)      One (0<=I1<=15) of 16 Boolean
                            functions of I2,I3 (bitwise, like
                            ANDINT).  For any valid I1,
                            BOOLFUNC(I1,5,3)=I1.
B T,T     CALLMIC           Uses MIC to perform other tasks and
                            optionally return
T T,T     CHECKEXTENSION    Adds default extension if file spec
                            contains no dot and is not just of
                            the form DEV:
I I1,I2,I3,I4 DEPBYTE(*) I=I2 with byte at bit I3 of length I4
                            replaced by I1.
P X,I     ECHO(*)           Suppresses monitor echoing of
                            terminal input
I X,T     FILCOP(*)         Efficient copying of disk files.
                            Also copies creation date and
                            version.
K         FILED             Reads and writes DEC 10 line numbered
                            files
T X,I     FILSPC            Returns file specification string for
                            file X in format controlled by value
                            of I.
I I       FLOKUP(*)         Look up file specified by FILOP. and
                            LOOKUP blocks.
I I1,I2   GETTAB(*)         Returns item I1 in monitor table I2
T I       IDRX50(*)         Interprets a 36-bit word as a
                            "RADIX50" symbol (code bits and
                            6-character identifier)
T I1,I2   IDSIXBIT(*)       ASCII representation of up to 12
                            character identifier given in I1 and
                            I2 in SIXBIT (DEC 64-character code)
I R       INTREA(*)         "Retype" R as integer (same 36-bit
                            pattern)
I X       JOBSTATUS(*)      Get JOBSTS word for PTY or TTY
                            (subjob control)
I I1,I2   LOADBYTE(*)       Get any byte in readable core.
I I       LOADWORD(*)       Get word at address (I) - any
                            readable word.
I I1,I2,I3 MATCH6(*)        SIXBIT match of I1 to I2 according to
                            wildcard mask I3.
DECsystem-10 SIMULA Language Handbook, part III           Page 16
0.2 SUMMARY LIST OF ROUTINES


B         NUMBERED(*)       Did last inimage get a line-numbered
                            line?
T T,I     OCTAL(*)          Octal representation of I, using T as
                            work area.
I X,R     PTYCHECK(*)       Any PTY (Infile X) activity in R
                            seconds?
X X       PTYFIL(*)         PTY Outfile companion to PTY Infile
                            X.
I X       PTYINIMAGE(*)     Get line of input from PTY Infile X.
                            Result shows how line ended.
I T,I     RDX50             Converts I,T to "RADIX50"
R I       REAINT(*)         "Retype" I as real (same 36-bit
                            pattern)
B X/T,T[,B] RENAME(*)       Renames or deletes first arg (file
                            ref/spec) to second arg (file spec).
B         RESCAN(*)         Makes invoking monitor command
                            readable by invoked program
M         SIMATR            Displays the information in an ATR
                            file
I T       SIXBIT(*)         First 6 characters in T converted to
                            sixbit word.
I I1,I2,I3 STOREBYTE(*)     Stores the byte I1 using byte pointer
                            I2, modified (I3) bytes.
I I1,I2   STOREWORD(*)      Store I1 at (I2) (abs memory
                            address).
I I       SXRX50             RADIX50 to SIXBIT.
T T,B     TMPIN(*)          Reads a "TMPCOR" core file into a new
                            text object, and deletes the file if
                            B is TRUE.
T T       TMPNAM(*)         Creates a temporary file name like
                            "021PIP.TMP"
B T1,T2   TMPOUT(*)         Writes a "TMPCOR" core file from T2.
                            Returns TRUE if successful.
I I,X,I   TRMOP(*)          Modifies monitor-terminal interface
I I       TTYLINE           Gives network node and line for tty
                            number I
T I1,I2   TTYNUMBER         TTY number for node I1 line I2 in
                            network
I I1,I2,B,I3 XCALLI(*)      Execute CALLI AC1,(I2).  AC1=I1.
                            Return (I3) if CALLI does not skip
                            and B is TRUE, otherwise return new
                            value of AC1.
I T,I1,I2 WILDSIX(*)        SIXBIT translation of T, recording
                            wildcards (?  or *) in I1.
DECsystem-10 SIMULA Language Handbook, part III           Page 17
1. UTILITY PACKAGES


1.  UTILITY PACKAGES
--------------------

1.1  APPLICATION PACKAGES

**** SAFEIO is a package to enable a safe question-and-answer
     dialogue with a conversational terminal.  The programs in
     the package allow you to ask the user for variables of
     various SIMULA types.  The user answers are checked for
     correct type and for acceptance according to criteria
     specified by the programmer.  Help and error messages are
     given.  The package protects from error interrupts in
     programs which may receive faulty input data from the user.
     The user may save his input in a log file.  This file can
     later be used as input instead of the terminal.  Other files
     may also be used as input, intermixed with terminal input.
     SAFEIO is distributed as the files SAFEIO.SIM, SAFMIN.SIM,
     SIMEIO.SIM, SIMMIN.SIM, SAFEIO.RNM, SAFEIO.MAN, SAFEIO.NEW,
     SAFMIN.HLP, SAFEIO.ENG, SAFEIO.SWE and SAFEIO.HLP.
     Written by Mats Ohlin, Swedish National Defense Research
     Institute.

     The SAFEIO system offers the following facilities in a
     single procedure call :


     1.      Issue a prompting question to the user.

     2.      Store the input in a simple variable.

     3.      Optionally accept default answers (equal to CR).

     4.      Check the syntax of the input.

     5.      Issue an appropriate message if the input is
             invalid.

     6.      Issue an explanatory message if the user responds
             with anything starting with a question mark '?'.

     7.      Allow the user to substitute terminal input for disk
             file input.  This may be done at any time a question
             is to be answered.

     8.      Allow the user to save all accepted program input on
             a disk file.  This file may be used as an input file
             in a subsequent run.  Correspondence between saved
             and current question will be checked (option by
             default).

     It is assumed that the user type only one item on each input
DECsystem-10 SIMULA Language Handbook, part III           Page 18
1. UTILITY PACKAGES


     line.

     A question to the user is defined by the call:

     REQUEST("prompting question", default,
     ***input(variable,validity), " error message if not valid",
     helpproc_expression);

     The parameter default is usually a text (constant)
     containing a default answer value.  There is a SAFEIO
     attribute NODEFAULT which can be used if default answers
     should be prohibited.

     *** may be replaced by INT,REAL,LONGREAL,BOOL or TEXT.  For
     the BOOLINPUT procedure there is only one argument though,
     the receiving variable.

     VALIDITY is usually a Boolean expression involving VARIABLE
     but may also be a call of a Boolean procedure if more
     complicated validity checking is necessary.  If the SAFFEIO
     attribute CHECKVALIDITY is set to FALSE, no validity
     checking (i.e.  no evaluation of the 2nd parameter to the
     ***input procedure) will occur, thus speeding up SAFEIO
     execution.  Note, however, that this will endanger the
     security of your program.


     The error message is printed if VALIDITY becomes FALSE.  The
     prompting question will then be repeated.

     HELPPROC_EXPRESSION will be evaluated each time the user
     types in an answer beginning with a question mark '?'.

     The SAFEIO Boolean procedure HELP (with one text parameter =
     the help text) may be used for displaying a text on the
     user's terminal.

     If no special information should be issued the SAFEIO
     procedure NOHELP may be used.  (The message - "There is no
     help in this case." will be issued.)

     An example:

     BEGIN
         EXTERNAL REF (Infile) PROCEDURE findinfile;
         EXTERNAL REF (Outfile) PROCEDURE findoutfile;
         EXTERNAL TEXT PROCEDURE conc,upcase,frontstrip,
         rest,checkextension;
         EXTERNAL CHARACTER PROCEDURE fetchar,findtrigger;
         EXTERNAL LONG REAL PROCEDURE scanreal;
         EXTERNAL INTEGER PROCEDURE checkreal,checkint,
DECsystem-10 SIMULA Language Handbook, part III           Page 19
1. UTILITY PACKAGES


         scanint,ilog;
         EXTERNAL BOOLEAN PROCEDURE menu;
         EXTERNAL CLASS safeio;

         safeio(..<name of log file for input or "">,
             <"English" or "Swedish">..)
             ! Use "English" if you want English texts.
               Use "Swedish" if you want Swedish texts. ;

         BEGIN
             INTEGER i;   REAL x;   LONG REAL y;
             TEXT t;   BOOLEAN b;
             TEXT ARRAY table[1:4];

             request("Enter integer:","14",
             intinput(i,irange(i,1,20)),
             outofirange(i,1,20),
             help("...info issued at '?'.."));

             ! The default value is 14. Only positive numbers
             ! are allowed.;
             ! Note the use of the procedures IRANGE(i,low,high)
             ! and OUTOFIRANGE(i,low,high).
             ! See also Summary Chapter 5 in SAFEIO.MAN.;

             request("Enter real item:",nodefault,
             realinput(x,TRUE),"",nohelp);

             ! Default answer not allowed. Any legal real item
             ! is accepted since validity is TRUE.
             ! No help information available.;

             request("Enter long real value:","E1",
             longrealinput(y,y NE 0),
             "? Must not be zero.",nohelp);

             ! Default value is 10 = E1;

             request("Enter yes or no:",nodefault,
             boolinput(b),"",nohelp);

             ! Note that procedure boolinput has only one
             ! parameter.;

             table[1]:- Copy("START");
             table[2]:- Copy("END");
             table[3]:- Copy("GO");
             table[4]:- Copy("GOTO");

             request("Enter command:",nodefault,
             textinput(t,menu(t,i,table,4)),
DECsystem-10 SIMULA Language Handbook, part III           Page 20
1. UTILITY PACKAGES


             commandmessage(index),commandhelp(table,4));

             ! The user may use an abbreviated form when no
             ! ambiguity exists.
             ! (Exact matches are always considered correct.)
             ! The variable i will return the table index.
             ! The length of the table (4) must also be supplied.
             ! Note that the table must contain upper case
             ! letters only.
             ! The procedure MENU resides in LIBSIM and checks
             ! for correspondence between T and TABLE.;
             ! The text procedure COMMANDMESSAGE will tell the
             ! user if his (illegal) command was either
             ! Unknown or Ambiguous.

             ! A simple text request: ;

             request("Enter A or B:","A",
                textinput(t,t = "A" OR t = "B" OR
                t = "a" OR t = "b"),
                "? Answer A or B.",nohelp);

             ! The user may define his own boolean procedure for
             ! input validation if more complicated tests are
             ! necessary.;

             GO TO start;    ! Will restart from SAFEIO prefix;
                             ! START is a SAFEIO label located
                             ! just in front of INNER.;

             ! If the label EOF exists,
             ! End-of-file on SYSIN (=^Z)
             ! will jump to this label. If EOF does not not exist
             ! in the user program, the SAFEIO block will
             ! terminate through an internal SAFEIO jump.
             ! NOTE! Once Sysin.Endfile is TRUE, there can be no
             ! more input on Sysin! This mechanism will only
             ! work for blocks prefixed by SAFEIO
             ! (i.e. NOT when using NEW SAFEI(O)).;

         END of SAFEIO block;

     END of program;



     On receiving any SAFEIO question on the terminal
     the user may input one of the SAFEIO commands:

     ?         to get help information.
DECsystem-10 SIMULA Language Handbook, part III           Page 21
1. UTILITY PACKAGES


     !         FOLLOWED by:

     *         to change the switch:  Display-prompting-question.
     /         to change the switch:  Display-default-value.
     =         to change the switch:  Display-input (+ the *- and
               /-switches).
     [         to change the switch:  Trace (file messages).
     +         to close and reopen current recording file in
               append mode.
     ;         to treat the line as a comment.
     %         to call special procedure.
     &         followed by input to override validity test.
     <FIL.EXT to open new input file in wait mode.  Default
               extension =.saf
     _         to continue input in nowait mode.
     <         to close current input file.
     ^ (uparrow) to close all active input files.
     _FIL.EXT to open new input file in nowait mode.  Default
               extension =.saf
     >FIL.EXT to open new recording file.  Default extension
               =.saf
     >         to close current recording file.
     ?         to print this text.

     Anything else following !  will cause current question to be
     displayed.

     The != command will always change the values of the switches
     Display-prompting-question and Display-default-value to the
     same value as the switch Display-input.

     Note that the !& facility may be switched off by calling the
     procedure NOOVERRIDE.

     The !% facility gives the programmer the possibility to
     declare his own procedure SPECIAL (with exactly that name
     and without parameters) which will be called when the user
     responds with !%.  It is possible to interpret the
     information following the !% in the procedure, thereby
     expanding the power of the SAFEIO - !  commands.  See
     SAFEIO.MAN for further information on SAFEIO attributes.

     If you are using SAFEIO via INSPECT it is not meaningful to
     specify any initial recording file, since it will be closed
     immediately.  This is because the INNER in SAFEIO will be
     passed.  In order to close all possible open SAFEIO files,
     end the connection block with a call of the SAFEIO procedure
     closefiles.  I.e.  :

     BEGIN   EXTERNAL declarations.....;
DECsystem-10 SIMULA Language Handbook, part III           Page 22
1. UTILITY PACKAGES


         ....
         INSPECT NEW SAFEIO("","") DO ! Default
         language is English ;

         BEGIN .... using SAFEIO ......
               closefiles;
         END;

     END program

     By substituting the class SAFEI for SAFEIO (with the
     language parameter only) the facilities numbered 1 to 6 will
     still be present while the file handling facilities will
     absent.  The class SAFEI requires about 2/5 as much core as
     SAFEIO.

     By substituting SAFMIN still more SAFEIO facilities are
     excluded.  See SAFMIN.HLP.  The size of SAFMIN is about 1/2
     that of SAFEI.

     The three classes SIMMIN, SIMEI and SIMEIO are identical in
     all respects to SAFMIN, SAFEI and SAFEIO respectively except
     that they are prefixed with SIMULATION.




**** SIMDBM Data Base Management System.

     SIMBDM is a data base handling system based on the ideas in
     the CODASYL DBTG proposal, but written entirely in SIMULA
     for use by SIMULA programs.  Facilities exist for defining
     SCHEMAs (Data Base Structure Descriptions) and storing them
     in the data base, for accessing the SCHEMA from the SIMULA
     program and for accessing data using the SCHEMA.  Data base
     fields of type TEXT or ARRAY have indefinite length.  New
     fields can be added to existing records.  Memory need not be
     reserved for the largest instance of each record type.  Data
     base records are mapped onto CLASS instances in core.  A
     SIMULA program can access and use the SCHEMA, which allows
     writing "data-independent" programs in SIMULA.

     Restrictions:  No built-in facilities exist for privacy
     constraints or for solving multi-terminal access conflicts.


     Written by Kalle Maekilae, Swedish National Defense Research
     Institute.
DECsystem-10 SIMULA Language Handbook, part III           Page 23
1. UTILITY PACKAGES


FILES ON THE DISTRIBUTION TAPE FOR SIMDBM:

     SIMDBM.DOC briefly describes the other files of the system.

     External classes for use with SIMULA application programs
     using SIMDBM:  DBMMIN.SIM, SIMDBM.SIM, DBMSET.SIM.  (.ATR
     and .REL files for these are part of SYS:LIBSIM).

     Documentation:  SIMDBM.DOC, SIMDBM.RNO, SIMDBM.HLP,
     NEWDBM.RNO.

     General purpose program (FETCH) for conversational queries
     to data bases:  FETCH1.SIM, FETCH2.SIM, FETCH.SIM,
     FETCH.RNO, HMESS.DMP, FETCH.EXE, DBLOAD.SIM, DBDUMP.SIM.

     Loading of SIMDBM-data bases from a sequential file:
     LOAD.SIM, LOAD.HLP, DBLOAD.SIM, DBDUMP.SIM.

     Text editing of SIMULA direct access files from a terminal:
     DIRED.SIM, DIRED.HLP.

     Entering a SCHEMA (Data Base Structure Specification) into a
     data base:  SPEC.SIM, SPEC.EXE.

     Preprocessor, producing SIMULA procedures for loading
     records from a SIMDBM data base:  PREP2.SIM.

     Preprocessor, producing SIMULA class with internal
     representation of records from a SIMDBM data base:
     PREP1.SIM.




**** STORE is a simple text oriented data base handler providing
     two main procedures PUTMESSAGE and GETMESSAGE.  PUTMESSAGE
     stores a message under a key in a direct access file, and
     GETMESSAGE returns the message stored under a given key.
     Both key and message can be text strings of arbitrary
     length.  STORE is distributed as the files STORE.SIM,
     STORE.RNO, STORE.HLP and STOREU.SIM.  STORE.RNO is STORE.HLP
     in RUNOFF format.  STOREU.SIM is an application example
     which also uses the SAFEIO package.
     Written by Jacob Palme, Swedish National Defence Research
     Institute.
DECsystem-10 SIMULA Language Handbook, part III           Page 24
1. UTILITY PACKAGES


**** SELECT is a SIMULA class to facilitate searching of TEXT
     strings or files applying Boolean conditions like
     "(SIMULA+ALGOL)&(DEC+DIGITAL)"
     The Boolean condition is first translated into a formula
     tree.  This formula tree can then be applied to any number
     of TEXTs, and TRUE will be returned for those TEXTs
     containing words satisfying the Boolean condition.

     Files:  SELECT.SIM, SELECT.RNH and SELECT.HLP.  In LIBSIM,
     SELECT.REL and SELECT.ATR can be available.

     Written by Jacob Palme, Swedish National Defence Research
     Institute.

**** GPSSS is a package which converts SIMULA (by additions
     within the language) into a programming language very
     similar to GPSS.

     GPSS is a well-known system for simulating systems of queues
     and work stations and objects moving from work station to
     work station.  GPSSS provides the same facilities in SIMULA,
     including the built-in standard statistics, in a way which
     is very similar to GPSS.  The advantage with using GPSSS may
     be that you can easier go outside the GPSS boundaries, since
     SIMULA is a much more general-purpose language.

     GPSSS may also be useful for introducing SIMULA to people
     who know GPSS.

     GPSSS was originally written by Professor Jean G.  Vaucher
     at the Universit'e de Montr'eal, and was converted to
     DECsystem-10 by Joakim Bose.

     GPSSST is an extended version of GPSSS with much more
     tracing facilities.

     Further information, see GPSSS.MAN.

     GPSSS is distributed on the SIMULA distribution tape in the
     following files:  GPSSS.SIM, GPSSST.SIM, GPSSS.ATR,
     GPSSST.ATR, GPSSS.REL, GPSSST.REL.  An english-language
     manual is available in the files GPSSS.RNM, GPSSS.MAN.  The
     tape also includes IBM SIMULA versions as GPSSS.IBM and
     GPSSST.IBM.  A swedish language version of the manual is
     included as the files GPSSWE.RNM and GPSSWE.MAN.
DECsystem-10 SIMULA Language Handbook, part III           Page 25
1. UTILITY PACKAGES


**** FIGURE is a basic graphic package for handling TEKTRONIX
     graphic terminals in SIMULA.  FIGURE is described in the
     help file FIGURE.HLP.
     Written by Aake Blomberg, Swedish National Defence Research
     Institute.


**** VISTA is a package to get full control of an alphanumerical
     display terminal.  You can move the cursor freely around the
     screen, and produce programs for e.g.:

   > Moving pictures,

   > Continuously changing tables,

   > Form-fill-in method of data entry with immediate validity
     checking of each field,

   > Table-fill-in method of data entry with immediate validity
     checking of each field.

     VISTA will not work on all kinds of alpahnumeric display
     terminals.  At the time of this writing, the package works
     on the following terminal types:

     Infoton VISTA, VISTAR SATTELITE and I 200, DEC VT52, TEC
     MINITEC and TELE-TEC, BEEHIVE B100, MINIBEE, TANDBERG TDV
     2000, Datamedia ELITE 1520 , 2520, 3025, CDC 713-10, Volker
     404.

     Work is going on to modify it for other terminals.  In many
     cases, the user can in a simple way describe a new kind of
     terminal by a few keystrokes when running the package.

     See the VISTA.MAN handbook for current information on which
     terminals can be handled by the package.

     VISTA.PAP contains a textual description of what can be done
     with the VISTA package, VISTA.MAN(VISTA.RNM) contains a
     programmers manual to the package.

     Files:  VISTA.SIM, FORM.SIM, CAT.SIM, SHIP.SIM, QSIM.SIM,
     VIDED.SIM, TERMTY.SIM, GETVIS.SIM, VIDED.MAN, VIDED.HLP,
     FORMT.SIM, VISTA.RNM, VISTA.RNH, VISTA.PAP.

     Written by Jacob Palme, Swedish National Defence Research
     Institute.
DECsystem-10 SIMULA Language Handbook, part III           Page 26
1. UTILITY PACKAGES


**** FORM package for formula input using VISTA, see above.


**** GETVIS procedure for finding out what kind of terminal the
     user has from SWITCH.INI, TMP:TRM, command line or user
     input, before calling VISTA;  see above.


**** DAHELP

     The DAHELP class may be used in order to save core in
     application programs when the HELP text segments are very
     long and/or numerous.

     If you prepare a number of sequential files with names equal
     to the respective keywords, the MAKHLP program may be used
     in order to create a DAHELP direct access file.  This file
     could then be used by the DAHELP class in order to display
     any of the included (sub)files on the terminal (i.e.
     Sysout).  It is also possible to make DAHELP list all
     entries (keywords) in the DAHELP file.

     Written by Mats Ohlin, Swedish National Defense Research
     Institute.  Files:  DAHELP.SIM, DAHELP.HLP, and in LIBSIM
     DAHELP.ATR, DAHELP.REL.


**** SQHELP is a program to simplify the provision of a help
     facility in a conversational program, where different parts
     of the help file may be printed via different help requests
     in the program.

     SQHELP makes a sequential search of the help file, and
     displays all pages containing a certain word.  Compared to
     DAHELP, this has the following advantages and disadvantages:

   > The help file can be a sequential file, readable also via
     the monitor HELP command and requiring less core than direct
     access files.

   > The user can supply key words to guide the help file search.

   > Much slower than DAHELP, not suitable for very large help
     files.

   > The search is governed by words contained in the help file
     text, not by the title of the help file segments.

     Files:  SQHELP.SIM, SQHELP.RNH and SQHELP.HLP.  LIBSIM can
     contain SQHELP.ATR and SQHELP.REL.
DECsystem-10 SIMULA Language Handbook, part III           Page 27
1. UTILITY PACKAGES


     Written by Jacob Palme and Mats Ohlin, Swedish National
     Defence Research Institute.


1.2  DEMONSTRATION PROGRAMS

     The save set SIMDEM on the SIMULA distribution tape contains
     some simple SIMULA programs which can be used to demonstrate
     the ideas of the SIMULA programming language.  (Written by
     Jacob Palme.)

     The programs are:

     QASETE, which is a very simple question-answering system
     accepting statements like "BOOK IS DOCUMENT.  DOCUMENT IS
     OBJECT." and being able to answer questions like "IS BOOK
     OBJECT?".

     STAT1E, which is a very simple simulation program of the
     transport operation between a harbour, a store and a
     factory.  The simulation program lacks all tracing and
     result output.

     STAT2E is the same simulation program as in STAT1E, but with
     tracing and result output added without obscuring the logic
     of the simulation program.  The intention is to illustrate
     the power of the SIMULA language for this kind of structured
     programming.

     DDTDEM which is a simple program to demonstrate SIMDDT.
     STAT1E can also be used to demonstrate SIMDDT.

     CAT, SHIP and QSIM are simple demonstrations of simulations
     using the VISTA package for "moving pictures" on
     alphanumeric display terminals.  CAT is a cat-and-mouse game
     on the screen, SHIP a troup transport simulation, QSIM a
     simulation of a doctor's waiting room.

     FORMT and TABLE are simple demonstrations of the form
     methods for data collection, based on the VISTA package.
DECsystem-10 SIMULA Language Handbook, part III           Page 28
2. SIMULA SOURCE PROGRAM CONVERSION PROGRAMS


2.  SIMULA SOURCE PROGRAM CONVERSION PROGRAMS
---------------------------------------------


**** SIMED converts SIMULA source programs to a more readable
     format.  The block structure is indicated by indentation and
     reserved words are (optionally) capitalized to distinguish
     them from other identifiers.  SIMED is described further in
     the DECsystem-10 SIMULA Language Handbook Part II Appendix
     L.  SIMED is distributed as four files, SIMED.SIM, SIMED.HLP
     and SIMED.EXE.
     Written by Mats Ohlin, Swedish National Defence Research
     Institute.

**** SIMSTR [NOT READY]
     Documents a SIMULA program by extracting only structural
     lines from the program.

**** IBMSIM converts SIMULA source programs from IBM 360/370 to
     DECsystem-10.  The program is described in Appendix M.1 of
     the DECsystem-10 SIMULA Language Handbook Part II.  IBMSIM
     is distributed as three files, IBMSIM.SIM, IBMSIM.HLP and
     IBMSIM.EXE.
     Written by Mats Ohlin, Swedish National Defence Research
     Institute.

**** SIMIBM converts SIMULA source programs from DECsystem-10 to
     IBM 360/370.  The program is described in Appendix M.2 of
     the DECsystem-10 SIMULA Language Handbook Part II.  SIMIBM
     is distributed as three files, SIMIBM.SIM, SIMIBM.HLP and
     SIMIBM.EXE.
     Written by Mats Ohlin, Swedish National Defence Research
     Institute.

**** CDCSIM converts SIMULA source programs from CDC to
     DECsystem-10.  The program is described in Appendix M.3 of
     the DECsystem-10 SIMULA Language Handbook Part II.  CDCSIM
     is distributed as two files, CDCSIM.SIM and CDCSIM.EXE.

     Originally produced at the Norwegian Computing Center,
     modified by Lars Enderin and Jacob Palme at the Swedish
     National Defence Research Institute.

**** SIMEXP merges a SIMULA source program and the external
     modules it refers to into a single segment.  This is
     sometimes necessary when moving SIMULA programs from the
     DECsystem-10 to other computers.  SIMEXP is described in
     SIMEXP.HLP and distributed as SIMEXP.SIM and SIMEXP.EXE .
     Written by Sten Perers, Swedish National Defence Research
     Institute.
DECsystem-10 SIMULA Language Handbook, part III           Page 29
2. SIMULA SOURCE PROGRAM CONVERSION PROGRAMS


**** FQC measures the frequency with which the statements in a
     SIMULA program are executed.  FQC is described in Appendix J
     in the DECsystem-10 SIMULA Language Handbook Part II.  FQC
     is distributed as FQCRED.SIM, FQCRED.EXE, FQCLST.SIM,
     FQCLST.EXE, FQC.HLP.
     Written by Stefan Arnborg, modified by Dag Gruneau and Mats
     Ohlin, Swedish National Defence Research Institute.
DECsystem-10 SIMULA Language Handbook, part III           Page 30
3. DIRECTFILE HANDLING PROGRAMS


3.  DIRECTFILE HANDLING PROGRAMS
--------------------------------


**** DIRED program

     A general editor for DIRECTFILEs.

     Files:  DIRED.SIM, DIRED.SAV, DIRED.HLP.

     Written by Kalle Maekilae, Swedish National Defense Research
     Institute.


**** MAKEDF program

     Converts a sequential file into a DIRECTFILE and vice versa.
     If the sequential file is line numbered, the line numbers
     are used as locations for the DIRECTFILE.
     Files on the distribution tape:  MAKEDF.SIM, MAKEDF.EXE,
     MAKEDF.HLP.

     Written by Jacob Palme, Swedish National Defense Research
     Institute.


**** FETCH program

     FETCH is part of the SIMDBM package.  FETCH allows you to
     access the data base directly from a terminal, without
     running any programs.  Changes to the SCHEMA must however be
     made with the program SPEC.  See further the SIMDBM
     documentation.

     Written by:  Kalle Maekilae, Swedish National Defense
     Research Institute.


**** MAKHLP program

     The MAKHLP program modifies or creates a DAHELP Direct
     Access Help file by appending named sequential file
     references.

     MAKHLP can not delete any parts of the Direct Access file.
     For such purposes - reconstruct the file from scratch or use
     the DIRED program to patch up the file according to DAHELP
     format (imagesize:73).  See DAHELP.HLP for more information.

     Files on the distribution tape:  MAKHLP.SAV, MAKHLP.SIM,
     MAKHLP.HLP.
DECsystem-10 SIMULA Language Handbook, part III           Page 31
4. PROCEDURES NOT WRITEABLE IN SIMULA


4.  PROCEDURES NOT WRITEABLE IN SIMULA
    ----------------------------------

     NOTE:  Some of these routines are not yet written.  See the
     list in chapter 0.2, which indicates which routines are
     ready.

     The source code for these routines can usually be found in
     the large files LIBSM1.PAC and LIBSM2.PAC.  Unpack the
     individual files with the program FILPAC.SAV.  FILPAC places
     the unpacked files on DSKD.  If you want the files on
     another file structure, say DSKB, do .ASSIGN DSKB DSKD
     before running FILPAC.

4.1 TIME AND DATE

**** TEXT PROCEDURE TODAY

     Returns a reference to a text object of length 10 with
     contents:
     "yyyy-mm-nn"
     where yyyy is year, mm is month(in digits 01-12), nn is day
     (in digits 01-31).  This is the internationally standardized
     format for dates.


**** INTEGER PROCEDURE dayno

     Integer procedure DAYNO returns the ordinal day number in
     current year.

     EXTERNAL PROCEDURE required:  TEXT PROCEDURE today;

     BEGIN
         INTEGER day,month,year;   TEXT t;

         t:- today;
         month:= t.Sub(6,2).Getint;
         day:= 30*(month-1) + (4*month-7)//6;
         IF month > 4 THEN day:= day - 1 ELSE
         IF month = 2 THEN day:= day + 1;
         IF month > 2 THEN
         BEGIN   year:= t.Getint;
               day:= IF Mod(year,400) = 0 THEN day - 1 ELSE
               day - Sign(Mod(year,4));
         END After February;
         dayno:= day + t.Sub(9,2).Getint;

     END of dayno;
DECsystem-10 SIMULA Language Handbook, part III           Page 32
4.1 TIME AND DATE


**** TEXT PROCEDURE DAYTIME

     Returns a reference to a new text object of length 8 with
     contents:
     "hh:mm:ss"
     where hh        is hours
           mm        is minutes
           ss        is seconds.
     at the time of the call.

     This is the internationally standardized format for writing
     time-of-day.


**** PROCEDURE TIMELIMIT(maxtime);  REAL maxtime;


     The execution will be interrupted when the allotted time is
     up.  The parameter is the time limit in seconds.  If the
     argument is non-positive, the effect will be as if TIMELIMIT
     was never called.


**** REAL PROCEDURE CPTIME

     Returns total CPU time spent since the beginning of the
     SIMULA program execution, expressed in seconds.


**** REAL PROCEDURE CLOCKTIME

     Returned value is time of day in seconds, i.e.  the absolute
     difference between the results of two successive calls is
     the time which elapsed between the calls (except when
     passing midnight).
DECsystem-10 SIMULA Language Handbook, part III           Page 33
4.2 REAL-TIME FOR MULTI-TERMINAL SIMULTANEOUS I/O.


4.2 REAL-TIME FOR MULTI-TERMINAL SIMULTANEOUS I/O.


                                 NOTE

         These procedures will usually not work on the
         DECsystem-20 under the TOPS-20 monitor.



     The goal of this is to allow one program to talk
     simultaneously to several conversational terminals and other
     on-going processes (jobs) in the computer.  A break in one
     such dialouge should not inhibit the conversation with the
     other terminals and processes.

     Chapter 4.2.1 below describes three simple assembly
     procedures which you can use if you want to write your own
     scheduling of the parallel processes for handling the
     external devices.

     Chapter 4.2.2 and appendix A describe a simple scheduler for
     realtime applications written in SIMULA.  The scheduler
     allows you to use SIMULA processes, one for each external
     device.


4.2.1 BASIC ASSEMBLY PROCEDURES FOR REAL TIME

**** BOOLEAN PROCEDURE INPUTCHECK(inputfile);
     REF (infile) inputfile;

     The parameter infile is connected to an external device or
     another job process.  INPUTCHECK will return TRUE if an
     INIMAGE can be made on the INFILE without delay, that is if
     data for the INIMAGE is already available.  If the external
     device has no pending input, INPUTCHECK will return FALSE.
     INPUTCHECK will also return FALSE if the parameter is NONE,
     refers to a closed file or refers to a file where ENDFILE is
     TRUE.  Supported devices are those which can be used from
     SIMULA.  DSK is regarded to be ready for input without
     delay.  (WARNING:  INPUTCHECK may not work when heavy
     transmission of data is going on to the same terminal.  In
     that case, use of the TTYCHECK procedure may be a better
     alternative.) TTY and PTY are the primary devices
     considered.  See PTYCHECK etc in section 7 of this handbook.
     NOTE:  Will not work on DECsystem-20!
DECsystem-10 SIMULA Language Handbook, part III           Page 34
4.2 REAL-TIME FOR MULTI-TERMINAL SIMULTANEOUS I/O.


**** PROCEDURE SLEEP(sleepsec);  REAL sleepsec;

     This procedure takes one parameter of type REAL and will
     stop the execution for a real time interval of at least this
     duration.  Resolution is 0.001 on a DECsystem-10.
     A special version is needed on the DECsystem-20 (uses DISMS
     JSYS).

**** INTEGER PROCEDURE INPUTWAIT(filearray,maxtime);
     REF (infile) ARRAY filearray;  REAL maxtime;

     NOTE:  This procedure will not work on DECsystem-20!

     This procedure stops the executing SIMULA program until
     INPUTCHECK would be TRUE for at least one of the parameter
     files, or until MAXTIME seconds have elapsed.  MAXTIME = 0
     indicates no time limit on the wait.  Some of the array
     elements may be NONE.  Whenever INPUTCHECK would be TRUE for
     one of these files, execution of the SIMULA program
     continues.  If INPUTCHECK is already TRUE for one of the
     files when INPUTWAIT is called, then INPUTWAIT will return
     immediately to the calling program.  The procedure returns
     an integer which is the index of a file in the parameter
     array from which input has been received, not necessarily
     the first one if input has been received from more than one
     of the input files.  INPUTWAIT disregards those array
     elements which are NONE or which refer to closed files, and
     files with ENDFILE = TRUE.  If all the array elements are
     disregarded in this way, then inputwait does not stop
     execution but returns an integer which is 1 less than the
     lower bound of the parameter array.  If the wait was
     interrupted becuse of the time limit maxtime, then an
     integer which is 2 less than the lower bound of the
     parameter array is returned.
     Special feature:  If the first file to wake up the program
     is a PTY file, and it has no output ready (ready for
     Inimage), but it can accept input (i.e. output on the
     corresponding Outfile), the returned value is the array
     index as above + 2^18.
DECsystem-10 SIMULA Language Handbook, part III           Page 35
4.2 REAL-TIME FOR MULTI-TERMINAL SIMULTANEOUS I/O.


4.2.2 REALTIME - A SCHEDULER FOR TERMINAL PROCESSES

     REALTIME is a separately compiled CLASS written in SIMULA as
     a subclass to SIMULATION.  REALTIME is based on the idea
     that you have one SIMULA process connected to each
     conversational terminal.  The processes can then execute in
     parallel, and the SIMULATION scheduler is used to distribute
     the execution between the terminals.  The CLASS REALTIME is
     not only useful for simulation programs, it can also be used
     for other real time applications.

     A full description is included in appendix A.

     REALTIME will not work on DECsystem-20.




4.3 INPUT/OUTPUT

4.3.1 ASCII-FORMATTED I/O

**** INTEGER PROCEDURE linecount(pf);
     REF (Printfile) pf;

     The parameter should be a reference to an open printfile
     object.  Result:  Returns the value of the LINESPERPAGE
     attribute of the printfile.


**** TEXT PROCEDURE filename(x);
     REF (FILE) x;

     The parameter should be a simple valid reference to an
     object of an I/O class.  Returns a reference to a text
     object whose value is equal to the NAME parameter of the
     FILE object.  The resulting text value may or may not be
     stripped of blanks before return.


**** CHARACTER PROCEDURE insinglechar(inf);
     REF (Infile) inf;

     The parameter should be a reference to an infile object
     using a terminal or a disk file.  Returns next input
     character from the infile (after last INIMAGE) without
     waiting for break character.  Succeeding INIMAGE will begin
     reading after the last character which has been input with
     INSINGLECHAR.

     Restriction:  With the current release of DECsystem-10
DECsystem-10 SIMULA Language Handbook, part III           Page 36
4.3.1 ASCII-FORMATTED I/O


     SIMULA, INSINGLECHAR only works on the controlling terminal
     or a disk file.


**** CHARACTER PROCEDURE insngl(inf);
     REF (Infile) inf;

     The parameter should be a reference to an infile object
     using a terminal or a disk file.  Returns next input
     character from the infile (after last INIMAGE).  Unlike
     INSINGLECHAR, it works in line mode (waits for break
     character).  Succeeding INIMAGE will begin reading after the
     last character which has been input with INSNGL.


**** CHARACTER PROCEDURE getch

     GETCH is similar to INSINGLECHAR (see above) but has no
     parameter and always takes input from the conversational
     terminal controlling the current job.


**** BOOLEAN PROCEDURE ttycheck(timelimit);  REAL timelimit;

     TTYCHECK waits for an input character from the terminal and
     returns with the value TRUE if a character is typed in
     before TIMELIMIT seconds have elapsed, otherwise false.
     TIMELIMIT should not be greater than about 60 seconds.  If
     TIMELIMIT is exactly zero, TTYCHECK waits indefinitely for
     input.  TTYCHECK does NOT read the input, only checks for
     it.  GETCH can be used to read the actual character when
     TTYCHECK returns TRUE.  Ordinary SIMULA input procedures can
     also be used provided a line is typed in.


**** PROCEDURE outchr(ofile,c,n);
     REF(Outfile)ofile;  CHARACTER c;  INTEGER n;

     Outputs n identical ASCII characters to the file, which is
     normally a terminal.  Ofile.Image is not affected.
     If n<=0, no character is output, otherwise the character c
     is output n times.  The buffer is used directly.

     Note:  Use "forceout" before terminal input after the use of
     "outchr".  Warning:  ofile must be open, otherwise outchr
     will loop!
DECsystem-10 SIMULA Language Handbook, part III           Page 37
4.3.1 ASCII-FORMATTED I/O


**** PROCEDURE outstring(ofile,t);
     REF(Outfile) ofile;  TEXT t;

     Copies the text T directly to the output buffer bypassing
     Image.  T is not changed.  No output is forced.  Output will
     appear when (Break)Outimage or FORCEOUT is called.  ofile ==
     NONE is treated as Sysout.

     Note:  Use "forceout" before terminal input after the use of
     "outstring".


**** PROCEDURE forceout(ofile);
     REF(Outfile)ofile;

     Ensures that all previous output to the TTY made with OUTCHR
     or OUTSTRING reaches the TTY.  Use FORCEOUT before inputting
     anything from the terminal, to ensure that previous output
     reaches the terminal.  FORCEOUT checks if there is any
     unwritten output in the buffer, so you can call it with
     little cost before every input operation.

     A procedure similar to FORCEOUT, but much slower, could be
     written in SIMULA:

     BEGIN TEXT imagecopy;
       imagecopy:- ofile.image;
       ofile.image:- NOTEXT;
       ofile.breakoutimage;
       ofile.image:- imagecopy;
     END;


**** PROCEDURE read(..)

     Any parameters of type integer, (long) real or character.  A
     reference type parameter, if used, must be a reference to an
     object of class infile or directfile.  A parameter may be an
     array identifier of suitable type.

     New values for the actual parameters are obtained one by one
     from the current input file (initially SYSIN).  If a
     parameter is an array identifier, new values are read and
     assigned for all elements of the array.  A parameter which
     is a reference to an open infile or directfile causes all
     successive read operations (in the parameter list) to be
     applied to this file.
DECsystem-10 SIMULA Language Handbook, part III           Page 38
4.3.1 ASCII-FORMATTED I/O


**** PROCEDURE write(..)

     Any parameters of type integer, (long) real, character or
     text.  Constants and arrays are also allowed.  A reference
     type parameter, if used, must be a simple reference to an
     object of class outfile, printfile or directfile.

     Values of actual parameters are output one by one on the
     current output file (initially SYSOUT).  The output formats
     for the respective values are

                     this machine plus 1
     INTEGER i       outint(i,n) where n is the number of digits
                     printed for the largest possible integer on
                     this machine plus 1

     REAL x          print x in flexible format according to:

                     if x = 0 then outfix(x,0,w) else
                     if abs(x) >= 10^d then outreal(x,d,w) else
                     if abs(x) >= 10^(-e) then
                     outfix(x,d-ilog(x)+(if abs(x) >= 1 then 0
                     else -1),w)
                     else outreal(x,d,w);

                     where d is number of significant digits, e
                     is number of positions required for the
                     exponent part and w := e + d + 2 (sign and
                     dot positions).

     LONG REAL z     same as for real but for long real
                     significance

     CHARACTER c     outchar(c)

     TEXT t          outtext(t)

     If the actual parameter is an array identifier, the values
     of all its elements are output.  A parameter which is a
     reference to an open printfile, outfile or directfile,
     causes all successive output operations to be applied to
     this file.  Each call on WRITE ends with a call on OUTIMAGE
     which also is called implicitly if the image is filled
     before all parameters are processed.  The final OUTIMAGE
     concerns every file mentioned;  thus OUTIMAGE (for the
     previous file) is called when a new file reference is given
     as well as at the end of the parameter list.
DECsystem-10 SIMULA Language Handbook, part III           Page 39
4.3.2 UNFORMATTED (BINARY) I/O.


4.3.2 UNFORMATTED (BINARY) I/O.


     ***********************  WARNING  **************************
     * Use of the procedures described in this section may make *
     * your programs difficult to move to another SIMULA system.*
     ************************************************************

     Unformatted I/O is a tricky problem because we have many
     diverse requirements to put together, if possible, in one
     construct.

   > Very fast and efficient input and output of much data.
   > Simple input and output procedures, taking whole texts,
     arrays, or objects at a time.
   > General purpose input and output procedures, to be able to
     read and write easily any kind of file, e.g.  a file
     containing line numbered lines, an object program file, a
     file which was produced by FORTRAN binary output, a disk
     directory file etc. etc.

     Two procedures INPUT and OUTPUT have been written.

     The first parameter to INPUT is a reference to an object of
     the CLASS infile or directfile, the first argument to OUTPUT
     is a reference to an object of the CLASS outfile or
     directfile.

     Both these procedures can take any number of additional
     parameters of any SIMULA type except label, switch or
     procedure.  The action of OUTPUT is:

**** INTEGER PROCEDURE OUTPUT

     OUTPUT returns the number of characters (over)written in the
     file.  (Including any output produced which is not directly
     related to the parameters, e.g.  null characters, null words
     etc.  IF OUTPUT is made on a DIRECTFILE, it may be important
     for the user to know how many lines on the file that are
     covered by one or several calls to OUTPUT.  He can do this
     by dividing the sum of the INTEGERs returned from OUTPUT
     with (image.length+2) of the directfile.  Such a program
     will be machine-independent since OUTPUT returns number of
     characters.

     For parameters of type INTEGER, [LONG]REAL or BOOLEAN:  the
     value of the parameter is output in such a way that it can
     be read by a FORTRAN program.  One word (36 bits on the
     DECsystem-10) is output.  Two words (72 bits) are output for
     LONG REALs.
DECsystem-10 SIMULA Language Handbook, part III           Page 40
4.3.2 UNFORMATTED (BINARY) I/O.


     For parameter of type CHARACTER:  The internal value is
     output.  SIMULA systems which pack CHARACTERs in words will
     output only the character byte, systems which store
     CHARACTERs in full words will output the full word.

     For parameters of type TEXT:  First the LENGTH of the TEXT
     is output in the same way as if it had been given as an
     explicit INTEGER parameter to OUTPUT.  Then the characters
     of the text value are output in internal implementation
     dependent format (ASCII-7-bit code packed 5 characters to a
     word on the DECsystem-10).  If the characters are packed (as
     they are on the DECsystem-10) and the last output word is
     not full, then it is filled with NULL characters.  The
     output TEXT value may  n o t  be preceded by NULL characters
     to permit faster output of subtexts.  NOTEXT is output as
     only the integer LENGTH(=0), and nothing more.

     All characters which can be created with the procedure CHAR
     can be part of a TEXT which is written by OUTPUT and read by
     INPUT, and they should all be returned unchanged after
     OUTPUT and a corresponding INPUT.

     Note that for subtexts, only the subtext part of the value
     is output.  If several texts have a common part, the value
     is still output completely for each text.

     For parameters of kind ARRAY:  Each element of the ARRAY is
     output just as if it had been a non-array parameter to
     OUTPUT.  (Even for REF-arrays.) The dimensions and bounds of
     the ARRAY are not output.

     For parameters of type REF:
     All value attributes of the referred object except REF and
     REF-array attributes are output just as if these attributes
     had been parameters to OUTPUT.  REF or REF ARRAY attributes
     are not output at all.

     OUTPUT may, in an implementation dependent way, output other
     descriptive data about the structure of the CLASS to ensure
     correct input by INPUT as described below.

     If the argument to OUTPUT has the value NONE, then some kind
     of indication about this is output.

     The order in which the attributes are output is
     implementation dependent, and not necessarily the same as
     the order in which they are declared in the SIMULA source
     program.

     Important:  If the parameter to OUTPUT is qualified by a
     SUPERCLASS (an outer class) of the actual object to which it
DECsystem-10 SIMULA Language Handbook, part III           Page 41
4.3.2 UNFORMATTED (BINARY) I/O.


     refers, then only attributes of the SUPERCLASS are output.


**** INTEGER PROCEDURE INPUT

     INPUT works analogously with OUTPUT so that anything written
     with OUTPUT can be read with INPUT.

     The INTEGER value returned by INPUT is the number of
     characters read (see OUTPUT).  If all the data required
     could not be read because of end of file, the negated number
     of characters that were read is returned.  A call to INPUT
     when ENDFILE is already TRUE causes an error interrupt.

     For TEXT parameters, INPUT allocates a new TEXT of
     appropriate length using BLANKS and reads the string into
     the new TEXT.  POS of the new text is set to 1.

     For ARRAY parameters:  INPUT works just as if INPUT had been
     called once for each item in the array.

     For REF parameters:  INPUT may do a certain amount of
     implementation dependent checking for agreement between the
     data in the file and the structure of the class to which the
     REF parameter refers.  Those attributes of the CLASS which
     were output with OUTPUT will then be read in.  TEXTs will be
     allocated with POS = 1 and LENGTH as from the file.

     INPUT will only work correctly for REF parameters if the
     data at that place in the file was previously written via a
     REF parameter to OUTPUT in a SIMULA program, and if the
     qualification of CLASS object which was output and the
     qualification of the parameter which is input from the same
     place in the file agree in the following respects:


     1.  The order and type of all attributes which are output
         and later input agree.

     2.  An attribute which was a parameter to the CLASS in
         OUTPUT must also be a parameter in INPUT.

     3.  If the CLASS has superclasses, then the attributes must
         be distributed between the subclasses in the same way.

     4.  The number and bounds of the dimensions of ARRAY
         attributes must agree.

     5.  If the argument to OUTPUT had the value NONE, then the
         corresponding argument to INPUT must also have the value
         NONE.
DECsystem-10 SIMULA Language Handbook, part III           Page 42
4.3.2 UNFORMATTED (BINARY) I/O.


     However, even if the requirements above are not fulfilled,
     INPUT is still protected from changing any data in core
     except attributes of the CLASS of type INTEGER, REAL, LONG
     REAL, CHARACTER or TEXT, which are accessible to the
     programmer.

     The following characteristics need  n o t  agree between the
     CLASS in INPUT and the CLASS in OUTPUT:


     1.  The SIMULA source program identifier names of the
         attributes.

     2.  Number, type, qualification etc. of attributes which
         were not output with OUTPUT (e.g. REF or PROCEDURE
         attributes).

     3.  The executable code in the CLASS.

     4.  The structure of such subclasses which were not output
         with OUTPUT because of the qualification of the REF
         parameter to OUTPUT.

     Note that the data OUTPUT with an OUTPUT statements does not
     constitute any "logical block".  It is therefore possible to
     output certain data with "OUTPUT(file,a,b);" and then input
     the data with "INPUT(file,a);  INPUT(file,b);".

     The organisation of files produced by OUTPUT and read by
     INPUT should, if reasonably possible, be such that FORTRAN
     programs on the same computer can read and write such files.


**** INTEGER PROCEDURE PUTSIZE

     To help the programmer avoid overwriting previous
     information in a directfile there is an auxiliary INTEGER
     PROCEDURE PUTSIZE with the same kind of parameters as
     OUTPUT, except for the first parameter (giving the output
     file) which need not be given to PUTSIZE.  PUTSIZE will
     return the same integer as would be returned by OUTPUT if
     called with an identical parameter list.

**** BOOLEAN PROCEDURE BYPASS

     BOOLEAN PROCEDURE BYPASS(fileref,x) will move the internal
     buffer pointer x characters.  X may be negative if fileref
     is a directfile.  If end of file is encountered for an
     infile, BYPASS should return TRUE the first time;  if called
     again a run time error should occur.  The first parameter
     may refer to any kind of file except a printfile.
DECsystem-10 SIMULA Language Handbook, part III           Page 43
4.3.2 UNFORMATTED (BINARY) I/O.


There is a further BOOLEAN PROCEDURE LOOK which takes two
     parameters, the first a reference to an infile object, the
     second of type INTEGER, [LONG] REAL or CHARACTER.  LOOK
     examines the next word in the input buffer without reading
     it.  Array parameters are not allowed.  Should return TRUE
     if end of file is encountered;  run time error for the next
     call.

     LOOK might for example be used to check if a line is line
     numbered before reading the line.


COMBINING OUTPUT AND INPUT WITH INIMAGE AND OUTIMAGE.

     Future versions of DECsystem-10 SIMULA may, because of
     standardization work with other SIMULA systems, forbid the
     combination of OUTIMAGE and INIMAGE with OUTPUT and INPUT on
     the same file.  The user is strongly recommended not to use
     such a combination.

     At your own risk, OUTPUT and INPUT can be combined with
     OUTIMAGE and INIMAGE on the same file.  The file may be
     padded with NULLs after OUTIMAGE to a word boundary before
     the data written by OUTPUT.  OUTPUT and INPUT do not work
     through the IMAGE of the file, which is thus not touched in
     any way.

     For DIRECTFILES, OUTPUT and INPUT will not change the value
     of LOC.  The first OUTPUT or INPUT after an INIMAGE,
     OUTIMAGE or LOCATE will start at the indicated location.
     Successive OUTPUTs or INPUTs will start at the place in the
     file where the previous OUTPUT or INPUT stopped.  A call to
     LOCATE preceding OUTPUT or INPUT will cause the OUTPUT/INPUT
     operation to start at the indicated position.  Note that
     this means that an OUTIMAGE immediately after an OUTPUT may
     overwrite what was output with the OUTPUT.  (Since LOC was
     not changed).  OUTPUT may overwrite several lines in the
     directfile.

     OUTPUT and INPUT are allowed on INFILEs, OUTFILEs and
     DIRECTFILEs but not on PRINTFILEs.

     WARNING!!!!  The procedures above have not been approved by
     the SIMULA DEVELOPMENT GROUP.  If your programs rely on
     them, they may be difficult to transfer to SIMULA systems on
     other computers than the DECsystem-10.  This is especially
     true if you combine OUTIMAGE and INIMAGE with OUTPUT and
     INPUT on the same file.
DECsystem-10 SIMULA Language Handbook, part III           Page 44
4.3.3 FILE HANDLING


4.3.3 FILE HANDLING

**** REF (infile) PROCEDURE FINDINFILE(filespec);
     VALUE filespec;  TEXT filespec;

**** REF (directfile) PROCEDURE FINDDIRECTFILE(filespec,update);
     VALUE filespec, update;
     TEXT filespec;  BOOLEAN update;

**** REF (outfile) PROCEDURE FINDOUTFILE(filespec);
     VALUE filespec;

**** REF (printfile) PROCEDURE FINDPRINTFILE(filespec);
     VALUE filespec;

     The four procedures findinfile, finddirectfile, findoutfile
     and findprintfile are rather similar to the statements NEW
     infile, NEW directfile, NEW outfile, NEW printfile.  The
     difference is that the value NONE is returned, if such a
     file cannot be opened.  For directfiles, if the input
     parameter update is TRUE, NONE is also returned if such a
     file cannot be opened for output.

     Reasons why a file cannot be opened may be:

   > That an infile does not exist.
   > That the file exists, but the file protection system of the
     computer does not allow opening.
   > For a directfile with update=TRUE or for an outfile:  That
     you cannot open the file because someone else is updating
     it.

     If possible, the indicated file is reserved for the user so
     that "a:- finddirectfile(....,TRUE);  a.open;" will not fail
     because someone else opens the file between the two
     procedure calls in the example.

     Example of use:

     FOR D:- finddirectfile("....",TRUE)
     WHILE D == NONE DO sleep(10);
     Will sleep until the directfile is updateable.


**** BOOLEAN PROCEDURE SCRATCHFILE(filespec);
     VALUE filespec;  TEXT filespec;

     If the file indicated by filespec exists and the program is
     allowed to delete (scratch) it, the file is deleted
     (scratched).  The result is TRUE if a file could be deleted,
     FALSE if no file could be deleted.  Delete (scratch) implies
DECsystem-10 SIMULA Language Handbook, part III           Page 45
4.3.3 FILE HANDLING


     removing the file so that it becomes inaccessible to this
     and other programs on the computer.  File specifications of
     the form TMP:xxx are also acceptable and refer to incore
     files handled by the TMPCOR UUO on the DEC-system-10.


**** PROCEDURE CLOSEOPEN(f); REF (file) f;

     Closes and opens a file again. If the file
     is an infile, this will mean that input will start from the
     beginning
     of the file. If it is an out(print)file, then - if it was
     defined
     with /ACCESS:APPEND, the result up to point of calling
     CLOSEOPEN, will be secured against system break-down, else -
     the old information will be lost at next close.

     INSPECT f DO
     BEGIN TEXT t;
        t:- image; close; open(t);
     END;


**** BOOLEAN PROCEDURE DOTYPEOUT(tty); REF (outfile) tty;

     IF tty == conversational terminal AND
     the computer can restart typeout to the terminal
     THEN restart this typeout, beginning with the
     next outimage or breakoutimage, return TRUE;
     COMMENT on the DECsystem-10, the CTRL-O bit is reset;


**** INTEGER PROCEDURE LASTLOC(df);  REF (directfile) df;

     Lastloc returns the highest location of any image which has
     been written in the directfile during this or any previous
     use of the file.  Returns -1 when the directfile is not
     open.

**** INTEGER PROCEDURE MAXLOC(df);  REF (directfile) df;

     Maxloc returns the largest integer such that
     "locate(maxloc);  outimage;" will not cause any error
     interrupt of the program.
DECsystem-10 SIMULA Language Handbook, part III           Page 46
4.4 CONTROLLED ERROR HANDLING.


4.4 CONTROLLED ERROR HANDLING.

     See also the procedures SCANREAL, SCANINT and SCANFRAC in
     chapter 5 of this handbook for control of bad data errors.

     A proposal for advanced integrated error handling is
     described in appendix B.  It is not implemented and no
     promise is made to ever do that.





**** PROCEDURE enterdebug(maycontinue);  BOOLEAN maycontinue;

     The debugging system is entered.  If maycontinue is TRUE,
     execution of the SIMULA program is allowed to resume after
     the debugging session.


**** PROCEDURE abort(message); VALUE message; TEXT message;
     BEGIN
        IF message =/= NOTEXT THEN
        BEGIN
          outimage;
          outtext("EXECUTION TERMINATED "
          "DUE TO CALL OF ERROR PROCEDURE");
          outimage;
          outtext("MESSAGE: "); outtext(message); outimage;
        END;
        enterdebug(FALSE);
     END;


**** PROCEDURE forsim(n);  INTEGER n;

     FORTRAN subroutines called from SIMULA are not allowed to do
     I/O or otherwise access the FORTRAN high segment, since
     SIMULA requires the SIMULA high segment.  If you want to use
     a FORTRAN subroutine which uses facilities in the FORTRAN
     high segment, you can load your program with the FORSIM
     procedure.  References from FORTRAN subroutines to the
     FORTRAN high segment will then be trapped by FORSIM.  Note
     however that FORSIM does not perform any actual I/O, so the
     I/O in FORTRAN subroutines will become dummy statements.
     FORSIM may also be called from FORTRAN with no parameter.

     If n=0,           any attempt at I/O in a FORTRAN routine
                       is trapped and a message is written the
                       first time,  but execution continues.
DECsystem-10 SIMULA Language Handbook, part III           Page 47
4.4 CONTROLLED ERROR HANDLING.


     If n>0,           execution continues n-1 times,
                       and then the message is typed followed by
                       an error entry into SIMDDT.

     If n<0,           execution continues, and no message
                       is typed.




4.5 SCHEDULING AND JOB CONTROL


**** PROCEDURE run(filespec,entrypoint);
     VALUE filespec;  TEXT filespec;  INTEGER entrypoint;

     FILESPEC is a text expression specifying a file containing
     an executable program.  RUN will transfer control to the
     program specified without closing files.  If the program is
     not found in the user area, and device and ppn were not
     given, SYS:  is tried as device.  On failure, RUN aborts via
     HALT.
     NOTE:  If the RUN procedure is loaded in the high segment,
     it will be wiped out.  Thus only one attempt can be made.

     ENTRYPOINT is an integer in the range [1,16], which
     specifies where the program should be started.  ENTRYPOINT =
     1 is the normal value and specifies the standard entry point
     which is used when the program is executed via a monitor RUN
     command or the sequence GET, START.  The value 2 corresponds
     to the secondary entry of standard CUSP's like PIP, COMPIL,
     MACRO, LINK, SIMULA.  When started in this way, the CUSP
     will try to read a temporary command file, which may be in
     core as a so-called TMPCOR file with a three-character name,
     e.g. PIP or SIM.

     If the CUSP does not find the relevant TMPCOR file, it will
     look for a disk file with a name of the form jjjppp.TMP,
     where jjj is the decimal job number with leading zeros if
     necessary, and ppp is the three-character name.  Examples:
     007PIP.TMP, 129SIM.TMP.

     Filenames with the required format can be generated by the
     procedure TMPNAM.  Normally, a CUSP command file contains
     several lines specifying output and input files.  The last
     line can be a file specification for an executable program,
     followed by "!", e.g. a LOAD or EXECUTE command will
     generate a command file to the compiler whose last line is
     "LINK!" specifying that LINK-10 should get control at its
     secondary entry point.
DECsystem-10 SIMULA Language Handbook, part III           Page 48
4.5 SCHEDULING AND JOB CONTROL


     Command files may thus be generated in a SIMULA programs,
     and by using SAVE and RUN together, control may be
     automatically regained after executing another program.

     Example:  A SIMULA program could first save itself by
     calling the procedure SAVE (see below), then generate a
     command file to PIP, then call PIP with the procedure RUN,
     then via ! in the PIP command file cause PIP to return
     control to the saved SIMULA program.


**** BOOLEAN PROCEDURE submit

Parameters:  One text reference or text constant.

Result:  The parameter is a file reference with the same format
     as the text parameter to the class INFILE.  The file, if
     found, is put into the input batch stream on the computer.
     Returns TRUE if this could be done, FALSE otherwise.

     The current job continues, independent of the new file in
     the batch stream.

**** INTEGER PROCEDURE save(filespec,continueonerror);
     VALUE filespec;  TEXT filespec;  BOOLEAN continueonerror;

     The PROCEDURE save forces a garbage collection and then
     outputs all dynamic memory to the file described by
     filespec.  The default file extension is .SAV, which is
     supplied if no extension appears in filespec.  If
     filespec==NOTEXT, FREEZE (see below) is called from SAVE.

     The second parameter, CONTINUEONERROR, is TRUE if error
     messages from SAVE should be suppressed.  Failure will be
     indicated by the returned value, see below.  If
     CONTINUEONERROR is FALSE, the run time system may issue
     error messages and demand user response.  This may
     eventually lead to successful completion if the user elects
     to proceed after dealing with the error messages.

     Save returns a value which indicates program status on
     continuation.  The possible values for the returned value
     (S) are:

     S<0:  Some error occurred, e.g. the file specified may be
     protected.  The program may try to recover by giving another
     file specification and calling SAVE again.

     S=0:  The program was continued directly, save was
     successful.  This value is also returned if RESTORE was
     called, see below.
DECsystem-10 SIMULA Language Handbook, part III           Page 49
4.5 SCHEDULING AND JOB CONTROL


     1<=S<=16:  The program was restarted via the RUN procedure
     or an equivalent command or code sequence.  The normal value
     1 is assumed when the saved file is executed by a RUN
     monitor command or by the RUN procedure with second
     parameter = 1.  Values 2-16 occur if the second parameter to
     the RUN procedure is 2-16.


**** PROCEDURE restore(filespec); VALUE filespec; TEXT filespec; 

     The procedure RESTORE restores dynamic memory to the
     contents of the file indicated by filespec.  Execution is
     then resumed following the point where SAVE (or FREEZE) was
     called to create the file indicated by filespec.  SAVE is
     ignored and a warning message is issued when any file except
     sysin or sysout is open.
                        **** WARNING ****
     Sysin and sysout should both be the user terminal, since
     they will be read and written from the start when
     restarting, unless sysout is written in append mode (switch
     /ACCESS:APPEND).

     Sysin and sysout can also refer to the .CTL and .LOG file of
     a batch job.

     The SAVE-RESTORE facility is intended primarily for
     applications with a fairly time-consuming build-up phase,
     such as a large simulation, where one wants to explore
     different continuations from the same branching point.
     Together with the RUN procedure, which works like an
     extended RESTORE, one can build a "program system"
     consisting of many segments controlled almost fully by one
     or several SIMULA programs.  See further the RUN procedure
     (above).

**** PROCEDURE freeze(returncode);
     NAME returncode;  INTEGER returncode;  

     FREEZE is a simpler and smaller version of SAVE.  The
     parameter RETURNCODE assumes the same values as SAVE.  The
     files of the program are handled as in SAVE.  FREEZE does
     not itself write a save file but exits to monitor level,
     where the user can issue a SAVE command with an appropriate
     file name.  Execution can be continued by a START command,
     which will give a returned value = 1 in RETURNCODE.  (START
     can also be given with a non-zero argument, but this is
     tricky and not generally recommended, since it is impossible
     to guard against wild results).  The saved file can be
     handled as explained above.  If no save file is wanted, the
     user simply issues a CONTINUE command, giving the result
     RETURNCODE = 0, and execution continues.
DECsystem-10 SIMULA Language Handbook, part III           Page 50
4.5 SCHEDULING AND JOB CONTROL


**** PROCEDURE exit(n);
     INTEGER n;

     EXIT(0) terminates the program immediately, exactly as if
     the user had typed CONTROL-C (twice).  Useful if you want
     your program to terminate with some short message like
     "Thank you." instead of the standard message "End of
     execution...".  Note that you have to close your files
     (except TTY files) explicitly, since no checking of open
     files will occur.  EXIT(0) is therefore also useful where
     the program is to terminate without closing all files - not
     invoking the standard SIMDDT action.  Note that if EXIT(0)
     is called just before last END, CONTINUE will cause the
     standard termination message "End of execution.." to appear.
     One additional CONTINUE will invoke SIMDDT as usual.

     EXIT(1) will terminate execution just as if the final END of
     the program had been passed.  The standard message will
     appear.

     EXIT(2) will invoke SIMDDT in debug mode, and the user is
     free to do anything SIMDDT permits, including issuing the
     EXIT command to terminate execution.  C.f.  procedure
     ENTERDEBUG.

     Other values of n are reserved for possible extensions.
DECsystem-10 SIMULA Language Handbook, part III           Page 51
4.6 MEMORY HANDLING


4.6 MEMORY HANDLING [Not ready]

     This section concerns procedures which are not implemented
     with the current release of DECsystem-10 SIMULA.  We may
     perhaps never implement them.

4.6.1 PRIMARY MEMORY HANDLING


EXTERNAL INTEGER PROCEDURE freebits

Parameters:  One integer parameter.  Negative parameter means no
     garbage collection, zero or positive parameters means
     garbage collection.  If the parameter is positive, then it
     indicates the amount of core (in bits) that will be assigned
     to the job after the forced garbage collection, to be used
     up before the next automatic garbage collection.  If the
     parameter is too large, no error is caused, the system will
     then wait as long as technically possible before the next
     garbage collection.  If the parameter is zero the allocation
     will follow the default procedure.  For systems with fixed
     core size, positive and zero parameter will probably be
     equivalent.

Result:  Forces a garbage collection for non-negative parameter.
     Returns the integer value in bits of the amount of more
     memory that this program can allocate without causing an
     error interrupt.  For a virtual memory machine, the returned
     value is virtual core.  If the parameter is negative, then
     the returned value is as said above minus present amount of
     garbage.
DECsystem-10 SIMULA Language Handbook, part III           Page 52
4.6.2 VIRTUAL MEMORY HANDLING (OR OVERLAY FACILITY)


4.6.2 VIRTUAL MEMORY HANDLING

     This might use the overlay mechanism built into the
     DECsystem-10 linking loader.  Overlay might be between
     separately compiled segments in SIMULA.  Problems may occur
     with unique-numbered entry-points and with the debugging
     system?

     If overlay is considered, overlaying of SIMDDT with some
     other system functions should also be considered at the same
     time.

     Implementing overlay into the DECsystem-10 SIMULA system
     will give many technical difficulties with the debugging
     system, prototypes etc.  and should perhaps therefore have
     low priority, especially if the virtual memory system could
     be used instead.

     A way of making the virtual memory system on the
     DECsystem-10 work as an overlay system, with high
     efficiency, is to make a small change to the page fault
     handler allowing a user program to ask for certain pages to
     be swapped out.  We could then add to the SIMULA system a
**** PROCEDURE swap, with one or more parameters which are either
     EXTERNAL PROCEDUREs, or REF-s qualified by EXTERNAL CLASSes.
     SWAP will swap out all pages containing only object code for
     the parameter PROCEDUREs and CLASSes.  Note that the
     REF-parameters to SWAP may have the value NONE and still
     cause swapping out of object code.  Prefixing classes are
     not swapped out if not explicitly indicated.

     Example of use:
     BEGIN
        EXTERNAL PROCEDURE p; EXTERNAL CLASS a, b, c;
        EXTERNAL PROCEDURE swap;
        COMMENT a is prefix to b, b is prefix to c;
        REF (a) pa; REF(b) pb; REF(c) pc;
        swap(p,pb,pc); COMMENT will swap out the object
        code of p, b and c, but not the object code of a;
     END;

     At the same time, we should perhaps add procedures to SIMULA
     to be able to set the physical core limit and the physical
     guideline from a SIMULA program.

**** BOOLEAN PROCEDURE corelimit(i);  INTEGER i;
     COMMENT sets PHYSICAL CORE LIMIT.  The parameter "i" is
     limit in bits.  To get limit in pages, multiply by 36*512
     (if wordsize is 36 bits and pagesize is 512 words).  E.G.
     CORELIMIT(50*36*512) will set a limit of 50 pages.  Returns
     TRUE if setting was successful;
DECsystem-10 SIMULA Language Handbook, part III           Page 53
4.6.2 VIRTUAL MEMORY HANDLING (OR OVERLAY FACILITY)


?    Perhaps the parameter should be given in number of pages,
     not in number of bits????

**** BOOLEAN PROCEDURE COREGUIDE(i);  INTEGER i;
     COMMENT same for setting physical guideline;




4.7 ENVIRONMENT ENQUIRY

**** INTEGER PROCEDURE maxint

     The largest positive integer number.  

**** LONG REAL PROCEDURE maxreal

     The largest positive long real number.
**** LONG REAL PROCEDURE minreal
     The smallest normalized positive real number.



**** INTEGER PROCEDURE approx(a,b);  [LONG] REAL a,b;
     COMMENT Returns number of bits differing, or, if overflow, -
     maxint;


**** INTEGER PROCEDURE DIMENSIONS

Parameters:  One of kind ARRAY.

Result:  Number of dimensions (subscripts) of the ARRAY.


**** TEXT PROCEDURE IMPLEMENTATION

Parameters:  none

Result:  Returning a text reference to a text object with the
     value "DEC-10 KI" ("IBM 370/145", "UNIVAC 1110", etc).  The
     exact wording of this text is decided by each
     implementation, but the first word should indicate
     manufacturer, the following type and model if possible.  The
     procedure may optionally return the version of the SIMULA
     system e.g. "IBM 370/145 VERSION 3.03".

     A list of what the returned reference should begin with for
     some wellknown computers:  "IBM 360", "IBM 370", "UNIVAC
     11", "DEC-10", "CDC CYBER", "CII", "ICL SYSTEM-4", etc.
DECsystem-10 SIMULA Language Handbook, part III           Page 54
4.7 ENVIRONMENT ENQUIRY


**** TEXT PROCEDURE LOGINFO

Parameters:  none

Result:  Returns a text reference, machine-dependent, with the
     information customarily given at LOGIN or in a JOB card.
     (Monitor version, Project number, programmer number,
     external job number, internal job number, priorities,
     protection privilegies etc.)





4.8 PACKING INTO PARTS OF WORDS

     By Stephan Oldgren, ENEA Data AB


     This chapter describes two general-purpose and
     machine-independent packing procedures.  They will make it
     easier to produce programs which can be moved to other
     computers than the DECsystem-10.  Chapter 7 below describes
     more efficient, less general-purpose and more
     machine-dependent packing procedures.

**** BOOLEAN PROCEDURE PACK and
**** BOOLEAN PROCEDURE UNPACK are two external MACRO-10
     procedures which pack and unpack data in parts of words.


4.8.1  PACK and UNPACK, PARAMETERS

     In the most simple case the procedures can be called with
     four parameters as follows:

     Parameter kinds for procedure PACK:

     Parameter 1:  The area into which data are to be packed.
               This parameter can be of type INTEGER, REAL, LONG
               REAL or BOOLEAN and of kind SIMPLE or ARRAY.
               The procedure will check that the bounds of this
               area are not exceeded.

     Parameter 2:  A non-negative INTEGER which specifies the
               number of bits to be bypassed at the beginning of
               the area specified in parameter 1, before start of
               packing.  The purpose of this is to allow partial
               packing and unpacking.

     Parameter 3:  The data to be packed.  This parameter can be
DECsystem-10 SIMULA Language Handbook, part III           Page 55
4.8 PACKING INTO PARTS OF WORDS


               of type INTEGER, REAL, LONG REAL, CHARACTER,
               BOOLEAN or TEXT and of kind SIMPLE or ARRAY.
               Observe that TEXT variables should not be NOTEXT.

     Parameter 4:  An INTEGER indicating the size in number of
               bits of the packed field.  If parameter 3 is an
               array parameter 4 is the size for one element of
               the array .  The value of this parameter must be
               as follows:

               Type of      less than           greater than
               parameter 3  or equal            or equal
               INTEGER      WORD LENGTH          2
               REAL          - " -              10
               CHARACTER     - " -               7
               BOOLEAN       - " -               1
               LONG REAL    DOUBLE WORD LENGTH  10
               TEXT            7                 6





     The procedure will also accept any even number of parameters
     up to thirty.  Then parameters 5,7 etc.  are of the same
     kind as parameter 3 and parameters 6,8 etc.  are of the same
     kind as parameter 4.

     The procedure UNPACK takes the same parameters as procedure
     PACK and works conversely.

     All packing and unpacking is done independently of word
     boundaries.  If for example parameter 2 is 70 and parameter
     4 is 6, then the data will be packed into a 6-bit area
     consisting of the last two bits in the second word of
     parameter 3, and the first four bits of the third word.


4.8.2  PACK and UNPACK, ERROR HANDLING


     The program will be interrupted if the number of parameters
     is less than four or not even.  Before the interrupt, the
     following messages is written:
     "PARAMETER IS MISSING IN <procedure name> PROCEDURE"
     "?  ERROR IN JOB ...."
     "ZYQ214 ERROR IN UTILITY PROCEDURE"


     Control is transferred to SIMDDT.
DECsystem-10 SIMULA Language Handbook, part III           Page 56
4.8.1	PACK and UNPACK, PARAMETERS


     In the following cases the BOOLEAN procedure PACK will
     return the value FALSE:

     a) Parameters are of illegal type or kind.
     b) Bounds of area specified in Parameter 1 are exceeded.
     c) TEXT variable is NOTEXT.
     d) Parameter 4(,6 etc) has illegal value.
     e) Truncated bits of an INTEGER variable are significant
        (ie.  contain ones if positive variable or zeroes if
        negative variable).

     The procedure UNPACK will return FALSE in the same cases.


4.8.3  PACK and UNPACK, METHODS OF PACKING 

     INTEGERs and BOOLEANs are packed by deleting bits after the
     sign bit at the start of the word to be packed.

     CHARACTERs are packed by deleting the necessary bits in the
     left part of the word to be packed.

     REALs and LONG REALs are packed by deleting as many bits as
     necessary at the low order end of the (single or double)
     word to be packed.

     TEXTs are packed by conversion of the characters from
     ASCII-7 to SIXBIT if the parameter for size of the packed
     field is 6.  If the parameter is 7 , each character is
     transferred without conversion.  LENGTH and POS are not
     packed implicity.


4.8.4  PACK and UNPACK, METHODS OF UNPACKING


     INTEGERs and BOOLEANs are unpacked by copying the sign bit
     into the previously deleted bits.

     CHARACTERs are unpacked by returning previously deleted bits
     as zeroes.

     REALs and LONG REALs are unpacked by filling up the
     previously deleted bits with zeroes.

     TEXTs are unpacked by conversion of the characters from
     SIXBIT to ASCII-7 if the parameter for size of the packed
     field is 6.  If the parameter is 7, each character is
     transferred without conversion.  The LENGTH of the TEXT
     indicates the number of characters to unpack.
DECsystem-10 SIMULA Language Handbook, part III           Page 57
4.8.5  PACK and UNPACK, EXAMPLES





4.8.5  PACK and UNPACK, EXAMPLES

     Example of SIMULA main program:

     BEGIN
            EXTERNAL BOOLEAN PROCEDURE pack,unpack;
            BEGIN
                    ARRAY pool[1:100];
                    INTEGER i,j;
                    TEXT t,s;

                    ! check integer;
                    i:=-5;
                    Outint(i,2);        Outimage;
                    pack(pool,0,i,5);
                    unpack(pool,0,j,5);
                    Outint(j,2);        Outimage;

                    ! check text;
                    t:- Copy("*?AZz");
                    s:- Blanks(5);
                    Outtext(t);         Outimage;
                    pack(pool,30,t,6);
                    unpack(pool,30,s,6);
                    Outtext(s);         Outimage;

                    ! check illegal;
                    pack(pool,0,t);
            END;
     END of program


     Example of output from execution of the program above:

            -5
            -5
            *?AZz
            *?AZZ
            PARAMETER IS MISSING IN PACK PROCEDURE
            ? ERROR IN JOB 15 AT PACK O 002314
            ZYQ214 ERROR IN UTILITY PROCEDURE
            *
DECsystem-10 SIMULA Language Handbook, part III           Page 58
4.9 MIN AND MAX


4.9 MIN AND MAX

     These procedures are efficient - almost no overhead.



**** INTEGER PROCEDURE imax(x,y);
     INTEGER x,y;

     rmax:=IF x>y THEN x ELSE y;



**** INTEGER PROCEDURE imin(x,y);
     INTEGER x,y;

     imin:=IF x<y THEN x ELSE y;



**** REAL PROCEDURE rmax(x,y);
     REAL x,y;

     rmax:=IF x>y THEN x ELSE y;



**** REAL PROCEDURE rmin(x,y);
     REAL x,y;

     rmin:=IF x<y THEN x ELSE y;



**** LONG REAL PROCEDURE lmax(x,y);
     LONG REAL x,y;

     lmax:=IF x>y THEN x ELSE y;



**** LONG REAL PROCEDURE lmin(x,y);
     LONG REAL x,y;

     lmin:=IF x<y THEN x ELSE y;
DECsystem-10 SIMULA Language Handbook, part III           Page 59
5. ROUTINES WRITEABLE IN SIMULA.


5.  ROUTINES WRITEABLE IN SIMULA
    ----------------------------

     NOTE:  Some of these routines are not yet written.  See the
     list in chapter 0.2, which indicates which routines are
     ready and which are not.


     Most of the routines are writeable or almost writeable in
     SIMULA, and the SIMULA code for the procedures is given in
     full below to make it easy to move programs to installations
     which do not provide these procedures in their libraries.
     For certain procedures below, some TEXT parameters are
     VALUE-specified.  In these cases, an assembly procedure can
     usually be written which gives the same result in all cases
     without actually making any VALUE copying of the TEXT.
     However, a corresponding procedure written entirely in
     SIMULA must be VALUE- or NAME-specified to allow TEXT
     constants as actual parameters.


5.1 PARTITIONING OF TEXTS

**** TEXT PROCEDURE rest(t); TEXT t;

     Returns a subtext reference of a text starting at Pos.

     IF t =/= NOTEXT THEN
     rest:- t.Sub(t.pos,t.Length-t.pos+1);

**** TEXT PROCEDURE front(t); TEXT t;

     Returns a reference to the longest subtext of T before Pos.

     IF t =/= NOTEXT THEN
     front:- t.Sub(1,t.pos-1);

**** TEXT PROCEDURE from(t,i); TEXT t; INTEGER i;

     Returns a reference to the longest subtext of T starting at
     Pos = I.

     IF i <= t.Length THEN
     from:- IF i <= 0 THEN t ELSE t.Sub(i,t.Length-i+1);

**** TEXT PROCEDURE upto(t,i); TEXT t; INTEGER i;

     Returns a reference to the longest subtext of T before Pos =
     I.

     IF i > 0 THEN
     upto:- IF i > t.Length THEN t ELSE t.Sub(1,i-1);
DECsystem-10 SIMULA Language Handbook, part III           Page 60
5.1 PARTITIONING OF TEXTS


**** TEXT PROCEDURE frontstrip(t); TEXT t;

     Returns a reference to the longest subtext of T starting
     with the first non-blank character.

     BEGIN
       t.Setpos(1);
       WHILE t.More DO
       IF t.Getchar NE ' ' THEN
       BEGIN
         frontstrip:- t.Sub(t.pos-1,t.Length-t.pos+2);
         t.Setpos(0);
       END;
     END;


**** CHARACTER PROCEDURE fetchar(t,p);  TEXT t;  INTEGER p;

     Returns the P:th character from T.

     IF p >= 1 AND p <= t.length THEN
     fetchar:= t.Sub(p,1).Getchar;


**** PROCEDURE depchar(t,p,c);  TEXT t;  INTEGER p;  CHARACTER c;

     Deposits the character C in the text T at position P.  If P
     is out of range, no action will be taken;

     IF p >= 1 AND p <= t.Length THEN
     t.Sub(p,1).Putchar(c);


**** TEXT PROCEDURE tsub(t,p,l);   TEXT t;   INTEGER p,l;

     TSUB acts like text attribute Sub.  In cases where
     t.Sub(p,l) would have caused a run time error, NOTEXT is
     returned.

     IF p >= 1 AND l >= 0 AND p+l <= t.Length + 1 THEN
     tsub:- t.Sub(p,l);


**** TEXT PROCEDURE getitem(tt); NAME tt; TEXT tt;

     First any blanks or tabs after POS in the text are skipped.
     Then the procedure reads an item.  By an item is meant
     either an identifier (a letter followed by letters, digits)
     or a number (a series of digits which may contain one dot)
     or any other character except blank.

     The input text "IF CAR.WHEEL_SIZE > 13.5" will thus by
     successive calls to GETITEM give:
     IF/CAR/./WHEEL/_/SIZE/>/13.5

     The result is a reference to a subtext (not a copy) of the
DECsystem-10 SIMULA Language Handbook, part III           Page 61
5.1 PARTITIONING OF TEXTS


     text passed as a parameter, or NOTEXT if there are only
     blanks left or pos > length.

     Notes:
     1.  The position of the parameter starts from current pos.
     2.  Preceding blanks or tabs (if any) are skipped.
     3.  The resulting position indicator setting is that
         following the last character of the matched word;

     IF tt =/= NOTEXT THEN
     BEGIN
       CHARACTER window; INTEGER startpos; TEXT t;

       CHARACTER PROCEDURE Getchar;
       IF t.more THEN
       Getchar:= window:= t.Getchar ELSE GOTO out;

       BOOLEAN PROCEDURE idchar(c); CHARACTER c;
       idchar:= letter(c) OR digit(c);

       t:- tt; t.Setpos(tt.Pos);
       startpos:= t.length+1;
       Getchar;
       WHILE window = ' ' OR window = Char(9) DO Getchar;
       startpos:= t.Pos-1;
       IF NOT letter(window) THEN
       BEGIN
         IF digit(window) THEN WHILE digit(Getchar) DO;
         IF window = '.' THEN WHILE digit(Getchar) DO;
       END ELSE WHILE idchar(Getchar) DO;
       IF t.Pos > startpos + 1 THEN t.Setpos(t.Pos-1);
       out:
       getitem:- t.Sub(startpos,t.Pos-startpos);
       tt.Setpos(t.Pos);
     END;




                                 NOTE

         The procedures INITEM, LOOKAHEAD, OUTLINE,
         BREAKOUTLINE, INLINE all have a file reference
         parameter.  It may not be omitted - but may be NONE,
         in which case SYSIN or SYSOUT are assumed as
         appropriate.


**** TEXT PROCEDURE initem(fileref);
     REF(infile COMMENT or directfile;) fileref;

     Same as GETITEM for files.  LASTITEM is called before
     reading an item.  NOTEXT is returned if only blanks or tabs
     are left in the file or if ENDFILE is TRUE.  Note that since
     the ITEM-s are not copied, a call on INITEM may cause
     inimage and thus destroy previously located items, if they
DECsystem-10 SIMULA Language Handbook, part III           Page 62
5.1 PARTITIONING OF TEXTS


     have not been copied by the program.

     INSPECT fileref DO
     initem:- IF lastitem THEN NOTEXT
     ELSE getitem(image);




5.2 SEARCHING AND TESTING OF TEXTS

**** TEXT PROCEDURE scanto(tt,c); NAME tt; VALUE c;
     TEXT tt; CHARACTER c;

     SCANTO will scan from pos in TT until the next occurrence of
     the character C.  Pos of TT will be placed after the
     character found, and the subtext from previous pos up to but
     not including the found character will be returned as result
     (not copied).  If no C is found, the rest of the text is
     returned.

     BEGIN TEXT t; INTEGER p;
       t:- tt; p:= t.pos;
       WHILE t.more DO
         IF t.getchar = c THEN
         BEGIN
           scanto:- t.sub(p,t.pos-p-1);
           GOTO out;
         END;
       scanto:- from(t,p);
       out: tt.setpos(t.pos);
     END of scanto;


**** CHARACTER PROCEDURE findtrigger(master,triggers);
     NAME master;   TEXT master,triggers;

     Starting from current MASTER.POS, find first occurrence of
     any of the characters in TRIGGERS.

     BEGIN   CHARACTER c;   TEXT t;

         t:- master;
         WHILE t.More DO
         BEGIN   c:= t.Getchar;
             triggers.Setpos(1);
             IF scanto(triggers,c) =/= triggers THEN
             BEGIN !C found in triggers;
                 findtrigger:= c;
                 GO TO out;
             END
         END loop;
         out:  master.Setpos(t.Pos);
     END of findtrigger;
DECsystem-10 SIMULA Language Handbook, part III           Page 63
5.2 SEARCHING AND TESTING OF TEXTS


**** TEXT PROCEDURE skip(tt,c);  NAME tt;  TEXT tt;  CHARACTER c;
     Skip will skip all characters C in the text T starting from
     T.POS.  IF the next character (at T.POS) is not equal to C,
     T.POS will remain unaltered, otherwise it will be situated
     at the first character not equal to C.  Skip will also
     return the subtext rest of t.  ;

     BEGIN   TEXT t;
         t:- tt;
         WHILE t.More DO
         IF t.Getchar NE c THEN
         BEGIN   t.Setpos(t.Pos-1);
             skip:- t.Sub(t.Pos,t.Length-t.Pos+1);
             GO TO out
         END;
         out: tt.Setpos(t.Pos)
     END of skip;


**** BOOLEAN PROCEDURE frontcompare(string, config);
     VALUE  config;   TEXT string, config;

     Starting at current pos, does STRING begin with a substring
     equal to CONFIG?

     IF string.Length - string.pos + 1 >= config.Length THEN
     frontcompare:=
     string.Sub(string.pos,config.Length) = config;


**** BOOLEAN PROCEDURE upcompare

     Upcompare is similar to frontcompare except that a match is
     found also when the character in the first parameter string
     is a lower case letter and the other character is upper case
     of the same letter.


**** INTEGER PROCEDURE search(master, config);
     TEXT master, config;

     Returns pos of 1st character of the first substring equal to
     config, starting at the current Pos of MASTER.  If no such
     subtext exists, then the result is MASTER.Length+1.

     BEGIN
         WHILE master.Length - master.Pos + 1 >= config.Length DO
         IF master.Sub(master.Pos,config.Length) = config THEN
         GO TO out ELSE
         master.Setpos(master.Pos+1);
         master.Setpos(0);
         out:
       search:= master.Pos;
     END of search;
DECsystem-10 SIMULA Language Handbook, part III           Page 64
5.2 SEARCHING AND TESTING OF TEXTS


**** INTEGER PROCEDURE checkint(t);    NAME t;    TEXT t;

     CHECKINT analyses the text t from t.pos and on.
     If a getint operation from this position is legal the
     returned value is +1. If it would give an error - then
     if the remaining text string is blank, the result is 0,
     otherwise -1. Pos is placed after a legal item (+1),
     after the first non-blank illegal character (-1) or after
     the text if the rest is empty (0).
     C.f. SCANINT.

     Maxintegerlength and Maxfloatinteger are implementation
     dependent.
     See also procedure GETTYPE below.

     IF t.Strip.Length < t.Pos THEN t.Setpos(0) ELSE
     BEGIN   TEXT u;   CHARACTER c;   INTEGER p;   LONG REAL x;
        c:= ' ';   u:- t;
        WHILE (c = ' ' OR c= Char(9)) AND u.More DO c:=
        u.Getchar;
        IF c = ' ' OR c = Char(9) THEN !checkint:= 0; ELSE
        IF c = '+' OR c = '-' THEN
        BEGIN  c:= ' ';
           WHILE c = ' '  AND u.More DO c:= u.Getchar;
           IF Digit(c) THEN
           BEGIN   trymoredigits:
              WHILE c = '0' AND u.More DO c:= u.Getchar;
              p:= u.Pos - 1;
              WHILE Digit(c) AND u.More DO c:= u.Getchar;
              p:= (IF NOT Digit(c) THEN u.Pos-1 ELSE u.Pos) - p;
              IF p <= maxintegerlength - 1 THEN checkint:=  1
              ELSE
              IF p >  maxintegerlength + 1 THEN checkint:= -1
              ELSE
              BEGIN
                 x:= u.Sub(IF NOT Digit(c) THEN u.Pos-p-1 ELSE
                 u.Pos-p,p).Getreal;
                 checkint:= IF Abs(x)  <= maxfloatinteger THEN 1
                 ELSE -1
              END maxinteger digits;
              IF NOT Digit(c) THEN u.Setpos(u.Pos-1);
           END digits ELSE
           GO TO error
        END sign ELSE
        IF Digit(c) THEN GO TO trymoredigits ELSE
        BEGIN   error:   checkint:= -1   END;
        t.Setpos(u.Pos)
     END of checkint;


**** INTEGER PROCEDURE checkreal(t);   NAME t;   TEXT t;

     CHECKREAL analyses the text t from t.pos and on.  If a
     getreal operation from this position is legal the returned
     value is +1.  If it would give an error - then if the
     remaining text string is blank, the result is 0, otherwise
DECsystem-10 SIMULA Language Handbook, part III           Page 65
5.2 SEARCHING AND TESTING OF TEXTS


     -1.  Pos is placed after a legal item (+1), after the first
     non-blank illegal character (-1) or after the text if the
     rest is empty (0).  C.f. SCANREAL.

     Ln10, Lowtencharacter, Lnmaxreal, Maxdigits are
     implementation dependent.  See also procedure GETTYPE below.

     IF t.Strip.Length < t.Pos THEN t.Setpos(0) ELSE
     BEGIN   TEXT u;   CHARACTER c;   INTEGER expitem,p,p2;
     LONG REAL decitem;
        PROCEDURE skip;
        BEGIN   c:= ' ';
           WHILE (c = Char(9) OR c = ' ') AND u.More DO c:=
           u.Getchar
        END of skip;
        decitem:= 1.0&&0;
        u:- t;   skip;   p:= u.Pos - 1;
        IF c = ' ' OR c = Char(9) THEN !checkreal:= 0; ELSE
        IF c = lowtencharacter THEN
        BEGIN   testexp:   skip;   p:= u.Pos - 1;
           IF c = '+' OR c = '-' THEN
           BEGIN   c:= ' ';
           WHILE c = ' ' AND u.More DO c:= u.Getchar   END;
           IF Digit(c) THEN
           BEGIN   WHILE Digit(c) AND u.More DO c:= u.Getchar;
              p2:= IF NOT Digit(c) THEN u.Pos - 1 ELSE u.Pos;
              u.Setpos(p);
              IF checkint(u) = 1 THEN expitem:= u.Sub(p,
              p2-p).Getint ELSE
              GO TO error;
              u.Setpos(p2+1);
              IF decitem = 0 THEN checkreal:= 1 ELSE
              IF Ln(Abs(decitem)) + expitem*ln10 < lnmaxreal THEN
              checkreal:= 1 ELSE GO TO error
           END digit in exponent ELSE GO TO error
        END exponent ELSE
        IF Digit(c) THEN
        BEGIN  testdigits:   p:= u.Pos - 1;
           WHILE Digit(c) AND u.More DO c:= u.Getchar;
           p2:= IF NOT Digit(c) THEN u.Pos - 1 ELSE u.Pos;
           IF p2 - p > maxdigits - 1 THEN GO TO error;
           IF c = lowtencharacter THEN
           BEGIN  realpart:    decitem:= u.Sub(p,p2-p).Getreal;
           GO TO testexp   END ELSE
           IF c = '.' THEN
           BEGIN   testfrac:
              IF u.More THEN c:= u.Getchar;
              IF NOT Digit(c) THEN GO TO error;
              WHILE Digit(c) AND u.More DO c:= u.Getchar;
              p2:= IF NOT Digit(c) THEN u.Pos - 1 ELSE u.Pos;
              IF c = lowtencharacter THEN GO TO realpart
           END fraction;
           IF NOT Digit(c) THEN u.Setpos(u.Pos-1);
           checkreal:= 1
        END digit ELSE
        IF c = '.' THEN GO TO testfrac ELSE
DECsystem-10 SIMULA Language Handbook, part III           Page 66
5.2 SEARCHING AND TESTING OF TEXTS


        IF c = '+' OR c = '-' THEN
        BEGIN   c:= ' ';
           WHILE c = ' ' AND u.More DO c:= u.Getchar;
           GO TO
           IF c = lowtencharacter THEN  testexp ELSE
           IF Digit(c) THEN  testdigits ELSE
           IF c = '.' THEN  testfrac ELSE error;
        END sign ELSE
        BEGIN   error:   checkreal:= -1   END;
        t.Setpos(u.Pos)
     END of checkreal;


**** INTEGER PROCEDURE CHECKFRAC

     Same as checkint/checkreal for grouped items.


**** INTEGER PROCEDURE gettype(paratext);
     NAME paratext; TEXT paratext;

     Investigate the subtext of the parameter without leading
     blanks.  Will return:
   1 If the next item is readable by GETREAL and contains a dot
     and/or a lowtencharacter, else
   2 If the next item is readable by GETINT, else
   3 If the next item begins with a letter, else
   4 If the next item is not NOTEXT, else
   5 If the next item is NOTEXT(i.e.  if the parameter to gettype
     is either NOTEXT or a wholly blank TEXT);

     This procedure cannot be coded fully machine-independent,
     since the maximal size of integers and reals vary with the
     machine;


**** INTEGER PROCEDURE hash(t,n);  VALUE t;  TEXT t;  INTEGER n;

     Returns a hash coded value of T in the interval [0:N-1].  It
     is recommended to choose n as a prime number.

     BEGIN
       TEXT tstrip; INTEGER a;
       tstrip:-frontstrip(t.Strip);
       IF tstrip == NOTEXT then hash:= Mod(t.Length,n) ELSE
       BEGIN
         a:= Rank(tstrip.Getchar);
         if tstrip.Length > 3 then
         BEGIN
           a:= a + 8*Rank(tstrip.Getchar);
           a:= a +64*Rank(tstrip.Getchar);
         END;
         tstrip.Setpos(tstrip.Length);
         a:= a + 512*Rank(tstrip.Getchar) + t.Length;
         hash:= Mod(a,n);
       END;
DECsystem-10 SIMULA Language Handbook, part III           Page 67
5.2 SEARCHING AND TESTING OF TEXTS


     END of hash;



**** BOOLEAN PROCEDURE menu(t,i,table,n);
     NAME i;   TEXT t;   TEXT ARRAY table;   INTEGER i,n;

     The MENU procedure is designed to be used for validity
     checks in MENU-like command requests.  [See chapter 7 - MENY
     for command handling in Swedish.]

     The MENU procedure will check for nonambiguous
     correspondence between T and an element from the text array
     TABLE.  (Note that an exact match will always be accepted,
     even if it is a substring of another table element.) The
     table must contain upper case letters only with no trailing
     blanks.  The input may have lower case letters.  If no match
     is found, I will return 0.  If T is ambiguous, I returns -1,
     otherwise the table matching index will be returned.  An
     example:

     ! BEGIN   TEXT ARRAY menutable[1:5];
     !      INTEGER index;
     !      BOOLEAN ok;
     !      TEXT t;

     !      menutable[1]:- Copy("STOP");
     !      menutable[2]:- Copy("START");
     !      menutable[3]:- Copy("END");
     !      menutable[4]:- Copy("ENDURE");
     !      menutable[5]:- Copy("EXIT");

     !      t:- <... input ...>;
     !      ok:= menu(t,index,menutable,5);

     ! OK will become TRUE if T is equal to

     START           (INDEX =  2)
     start           (INDEX =  2)
     Sta             (INDEX =  2)
     sto             (INDEX =  1)
     enD             (INDEX =  3)
     endure          (INDEX =  4)
     endu            (INDEX =  4)

     and FALSE for

     ST              (INDEX = -1)
     x               (INDEX =  0)
     e               (INDEX = -1)
     en              (INDEX = -1)

     EXTERNAL Procedures required: TEXT PROCEDURE upcase;

         BEGIN   TEXT u;   INTEGER j,k,hit;
DECsystem-10 SIMULA Language Handbook, part III           Page 68
5.2 SEARCHING AND TESTING OF TEXTS


             ! Checking the array index bounds: ;
             OPTIONS(/A); COMMENT START ARRAY BOUND CHECKING;
             u:- table[1];
             u:- table[n];;
             OPTIONS(/-A); COMMENT NO ARRAY BOUND CHECKING;
             u:- upcase(t.Strip);

             FOR j:= 1 STEP 1 UNTIL n DO
             IF u = table[j] THEN
             BEGIN   hit:= 1;   k:= j;   GO TO ready  END
             ELSE
             IF u.Length < table[j].Length THEN
             BEGIN
                     IF u = table[j].Sub(1,u.Length) THEN
                     BEGIN   k:= j;   hit:= hit + 1   END
             END;

             ready:
             menu:= hit = 1;
             i:= IF hit = 1 THEN k ELSE Sign(-hit)

         END of menu;






**** BOOLEAN PROCEDURE lookup(t,ta,low,high,i);  NAME i;  TEXT t;
     TEXT ARRAY ta;   INTEGER low,high,i;

     Procedure LOOKUP will perform a binary search for T in the
     text array TA within the interval [LOW,HIGH].  The text
     array contents must be sorted in ASCENDING order!  (I.e.
     TA[J] < TA[J+1].  Use procedure SORTTA for sorting if
     necessary.) If the text is found in TA the matching index I
     will be returned (for which TA[I] = T) and LOOKUP will
     return TRUE.  If the text is NOT found LOOKUP will return
     FALSE and I will be either in the range [LOW,HIGH-1] in case
     TA[I] > T > TA[I+1] or else I = HIGH if T > TA[HIGH] or I =
     LOW-1 IF T < TA[LOW].
     Author:  Mats Ohlin, FOA 1, S-104 50 STOCKHOLM 80, SWEDEN.

     IF low <= high THEN
     BEGIN   INTEGER j;

         OPTIONS(/A); COMMENT START ARRAY BOUND CHECKING;
         IF
         ta[low] < t AND t < ta[high]
         THEN
         BEGIN ;
         OPTIONS(/-A); COMMENT NO ARRAY BOUND CHECKING;
             FOR j:= (low+high)//2 WHILE high > low + 1 DO
             IF ta[j] > t THEN high:= j ELSE
             IF ta[j] < t THEN low:= j ELSE
             BEGIN   lookup:= TRUE;   GO TO out  END
DECsystem-10 SIMULA Language Handbook, part III           Page 69
5.2 SEARCHING AND TESTING OF TEXTS


         END  inside range ELSE
         IF ta[low] = t THEN
         BEGIN   lookup:= TRUE;   j:= low END ELSE
         IF ta[high] = t THEN
         BEGIN   lookup:= TRUE;   j:= high END ELSE
         IF ta[low] > t THEN j:= low - 1 ELSE
         IF ta[high] < t THEN j:= high;

         out:  i:= j

     END of lookup;





5.3 OPERATIONS ON TEXTS


**** LONG REAL PROCEDURE scanreal(t);   NAME t;   TEXT t;

     Scanreal is similar to GETREAL, but the handling of ERROR
     conditions due to bad data is different.  Scanreal returns
     the value of the next real item in the text T.  T.Pos will
     only be moved if deediting was successful.

     BEGIN   TEXT s;   INTEGER p;
         p:= t.Pos;   s:- rest(t);
         scanreal:= s.Getreal;
         ! *** If this goes wrong, return -MAXREAL ELSE
         t.Setpos(p+s.Pos-1);
     END of scanreal;


**** INTEGER  PROCEDURE scanint(t);   NAME t;   TEXT t;

     Scanint is similar to GETINT, but the handling of error
     conditions due to bad data is different.  Scanint returns
     the value of the next integer item in the text T.  T.Pos
     will only be moved if deediting was successful.

     BEGIN   TEXT s;   INTEGER p;
         p:= t.Pos;   s:- rest(t);
         scanint:= s.Getint;
         ! *** If this goes wrong, return -MAXINT-1 ELSE
         t.Setpos(p+s.Pos-1)
     END of scanint;
DECsystem-10 SIMULA Language Handbook, part III           Page 70
5.3 OPERATIONS ON TEXTS


**** INTEGER PROCEDURE scanfrac

     Same as scanint/scanreal for grouped items.


**** TEXT PROCEDURE conc(t,...);   TEXT t,...;

     Text concatenation procedure.  Variable number of TEXT
     parameters.  Since the number of parameters is variable,
     CONC can NOT be written in SIMULA.  The parameters are
     handled as if transferred in reference mode, although
     constants are allowed.


**** TEXT PROCEDURE conc2(t1,t2);  VALUE t1, t2;  TEXT t1, t2;

     T1 and T2 are handled as if transferred by reference (text
     descriptors are copied) although constants are allowed.

     BEGIN TEXT c;
       c:- blanks(t1.Length+t2.Length);
       c.Sub(1,t1.Length):= t1;
       c.Sub(1+t1.Length,t2.Length):= t2;
       conc2:- c;
     END;


**** BOOLEAN PROCEDURE puttext(oldstring, newstring);
     NAME oldstring; VALUE newstring;
     TEXT oldstring, newstring;

     Puts the short word newstring into the long string
     oldstring.  Newstring is OUTPUT after POS in oldstring, and
     POS of oldstring is moved after the end of the new word.
     Returns FALSE if there was not room for the new string.

     BEGIN TEXT s;
       s:- oldstring;
       IF s.Pos+newstring.length-1 <=
       s.length THEN
       BEGIN
         puttext:= true;
         s.Sub(s.Pos,newstring.length):=
         newstring;
         s.Setpos(s.Pos+newstring.length);
       END;
       oldstring.Setpos(s.Pos);
     END;
DECsystem-10 SIMULA Language Handbook, part III           Page 71
5.3 OPERATIONS ON TEXTS


**** TEXT PROCEDURE upcase(t);  TEXT t;

     Will convert all lower case letters within T to the
     corresponding upper case letter.  No copying of the text.
     Only English alphabet letters (for which the procedure
     "letter" returns TRUE) are converted.

     IF t =/= NOTEXT THEN
     BEGIN
       CHARACTER c; INTEGER shift;
       shift:= rank('a') - rank('A');
       t.Setpos(1);
       WHILE t.more DO
       BEGIN
         c:= t.Getchar;
         IF letter(c) AND c >= 'a' AND c <= 'z' THEN
         BEGIN
           c:= char(rank(c) - shift);
           t.Setpos(t.Pos-1); t.Putchar(c);
         END;
       END;
       t.Setpos(1);
       upcase:- t;
     END;


**** TEXT PROCEDURE lowcase(t); TEXT t;

     LOWCASE is the opposite of UPCASE.  Defined via simple
     modifications of the UPCASE procedure definition.  Just
     exchange 'a' with 'A' and 'z' with 'Z'.


**** TEXT PROCEDURE maketext(c,n); CHARACTER c; INTEGER n;

     Returns a new text of length N filled with character C.

     IF n > 0 THEN BEGIN
       TEXT t;
       t:- blanks(n);
       WHILE t.More DO t.putchar(c);
       t.Setpos(1); maketext:- t;
     END;


**** TEXT PROCEDURE compress(t,c);   TEXT t;   CHARACTER c;

     COMPRESS returns NOTEXT (if T contains no other characters
     than a number of characters = C), or a reference to an
     initial subtext of T (altered) which contains all characters
     of T not = C.  The part of T after this subtext is
     unchanged.
     Example:  t1:-Copy("AxBxCxDx");  t2:-compress(t1,'x');
     gives t1="ABCDCxDx", t2==t1.Sub(1,4), t2="ABCD".

     BEGIN   TEXT s;   CHARACTER cc;
DECsystem-10 SIMULA Language Handbook, part III           Page 72
5.3 OPERATIONS ON TEXTS


       t.Setpos(1);   s:- t;
       WHILE t.More DO
       BEGIN   cc:= t.Getchar;
         IF cc NE c THEN s.Putchar(cc);
       END;
       compress:- front(s)
     END of compress;


**** INTEGER PROCEDURE startpos(t);   TEXT t;

     Procedure STARTPOS returns the starting position of the
     (sub)text T within T.Main.  Thus if T is a main text (T ==
     T.Main) the result is 1.  If T == NOTEXT, 0 is returned.
     Efficient MACRO-10 coded routine.

     IF t =/= NOTEXT THEN
     BEGIN   TEXT s; INTEGER p;
         s:- t.Main;
         IF s == t THEN startpos:= 1 ELSE
         BEGIN
             WHILE s.More DO
             BEGIN
                 p:= search(s,t);
                 IF s.Sub(p,t.Length) == t THEN
                 BEGIN   startpos:= p;   GO TO out   END;
                 s.Setpos(p+1);
             END loop
         END not main text;
         out:
     END of startpos;


**** PROCEDURE split(t,t1,delimiter,t2);
     NAME t1,t2;   TEXT t,t1,delimiter,t2;
     EXTERNAL Procedures required:
     TEXT PROCEDURE front,rest.
     INTEGER PROCEDURE search;

     This procedure splits the text T into two halves - the first
     part T1 denoting the part of T up to the text DELIMITER -
     and the second part T2 denoting the part of T following the
     DELIMITER.  Thus T1 + DELIMITER + T2 = T.  However, if no
     DELIMITER is found, T1 will return a reference to the whole
     of T, while T2 will return NOTEXT.  Note - if the delimiter
     is just one character long, procedure SCANTO is recommended
     for efficiency reasons.

         BEGIN   TEXT s1;
             t.Setpos(1);
             t.setpos(search(t,delimiter));
             s1:- front(t);
             t.Setpos(t.pos+delimiter.Length);
             t2:- rest(t);
             t1:- s1
         END of split;
DECsystem-10 SIMULA Language Handbook, part III           Page 73
5.3 OPERATIONS ON TEXTS


*** INTEGER PROCEDURE splita(t,del,ta,n);
     TEXT t,del;  TEXT ARRAY ta;  INTEGER n;

     This procedure splits the text T into parts separated by the
     text delimiter DEL and makes the elements of TA[1:N] denote
     the different parts of T (without DEL).  The returned value
     SPLITA is the number of parts found.  However, if more than
     N parts are found, the value -1 is returned.

     Note that if DEL is just one character, procedure SPLITC is
     recommended.  SPLITC is roughly twice as efficient as
     SPLITA.

     Author:  Mats Ohlin, FOA 1, Fack, S-104 50 STOCKHOLM 80,
     SWEDEN.

     EXTERNAL PROCEDURE required:  INTEGER PROCEDURE search;
     BEGIN   INTEGER i,p;
         OPTIONS(/A); ta[1]:- ta[n];; ! Check array bounds;
         OPTIONS(/-A);
         t.Setpos(1);
         FOR i:= i+1 WHILE t.More DO
         IF i>n THEN
         BEGIN   splita:= -1;   GOTO exit   END
         ELSE
         BEGIN   p:= t.Pos;
             t.Setpos(search(t,del));
             ta[i]:- t.Sub(p,t.Pos-p);
             t.Setpos(t.Pos+del.Length);
         END;
         splita:= i-1;
         FOR i:= i STEP 1 UNTIL n DO ta[i]:- NOTEXT;
         exit:
     END of splita;


**** INTEGER PROCEDURE splitc(t,del,ta,n);
     TEXT t;   CHARACTER del;   TEXT ARRAY ta;   INTEGER n;

     This procedure splits the text T into parts separated
     by the character delimiter DEL and makes the elements of
     TA[1:N] denote the different parts of T (without DEL).
     The returned value SPLITC is the number of parts found.
     However, if more than N parts are found, the value -1 is
     returned.

     Author: Mats Ohlin, FOA 1, Fack, S-104 50 STOCKHOLM 80,
     SWEDEN.

     EXTERNAL PROCEDURE required: TEXT PROCEDURE scanto;

     BEGIN   INTEGER i;
         OPTIONS(/A); ta[1]:- ta[n];; ! Check array bounds;
         OPTIONS(/-A);
         t.Setpos(1);
         FOR i:= i+1 WHILE t.More DO
DECsystem-10 SIMULA Language Handbook, part III           Page 74
5.3 OPERATIONS ON TEXTS


         IF i>n THEN
         BEGIN   splitc:= -1;   GOTO exit   END
         ELSE  ta[i]:- scanto(t,del);
         splitc:= i-1;
         FOR i:= i STEP 1 UNTIL n DO ta[i]:- NOTEXT;
         exit:
     END of splitc;


**** BOOLEAN PROCEDURE change(master,oldt,newt);   NAME master;
     TEXT master,oldt,newt;

     EXTERNAL Procedures required: TEXT PROCEDURE
     conc,from,front.
     INTEGER PROCEDURE search.

     Change will change the subtext OLDT in MASTER - if found
     when searching from MASTER.POS and on - to NEWT.  If
     OLDT.Length >= NEWT.Length then MASTER will denote (a
     subtext of) the original MASTER text, otherwise MASTER will
     denote a new text object.  Changing all occurrences of OLDT
     to NEWT may be done with the following procedure;

     ! PROCEDURE edit(master,oldt,newt);
     ! NAME master;
     ! TEXT master,oldt,newt;
     ! BEGIN  TEXT local;
     !    local:- master;
     !    WHILE local.More DO change(local,oldt,newt);
     !    master:- local
     ! END of edit;

     BEGIN   TEXT local;   INTEGER p;
       local:- master;
       p:= search(local,oldt);
       IF p <= local.Length THEN
       BEGIN   change:= TRUE;
         IF oldt.Length >= newt.Length THEN
         BEGIN   local.Sub(p,newt.Length):= newt;
           IF oldt.Length > newt.Length THEN
           BEGIN
             from(local,p+newt.Length):=
             from(local,p+oldt.Length);
             local:- local.Sub(1,
             local.Length-oldt.Length+newt.Length)
           END
         END ELSE
         local:-
         conc(front(local),newt,from(local,p+oldt.Length));
         local.Setpos(p+newt.Length);
         master:- local
       END ELSE master.Setpos(0);
     END of change;
DECsystem-10 SIMULA Language Handbook, part III           Page 75
5.3 OPERATIONS ON TEXTS


**** TEXT PROCEDURE puttime(field,time,unit,secdec);
     TEXT field;   REAL time;
     CHARACTER unit;   INTEGER secdec;

     Puttime edits a REAL variable representing a TIME value
     left justified into the text FIELD in
     seconds if UNIT = 'S'
     minutes if UNIT = 'M'
     hours   if UNIT = 'H'
     days    if UNIT = 'D'
     Else Putreal editing will be used.

     The FIELD must have a minimum length of
     12      if secdec < 0
     15      if secdec = 0
     16+secdec       if secdec > 0

     Format:

     [-]dddD  hh:mm[.ss[.xxx...]]

     where
     ddd     is number of days       (Blanked if day < 1)
     hh      is number of hours
     mm      is number of minutes
     ss      is number of seconds (only if SECDEC >= 0)
     xxx     is fraction of second with SECDEC digits

     PUTTIME also returns a reference to parameter FIELD.
     Thus it can be used as parameter to Outtext -
     i.e.  Outtext(puttime(field,Time,'H',-1);
     or editing Image directly -
           puttime(Image.Sub(Pos,17),Time,'H',-1);
     C.f. procedure OUTTIME.

     EXTERNAL PROCEDURE required: TEXT PROCEDURE putfloat;
     IF field.Length >=
     (IF secdec < 0 THEN 12 ELSE IF secdec = 0 THEN 15 ELSE
     secdec+16)
     THEN
     BEGIN   INTEGER days,hours,m,powersec;   REAL seconds;

         PROCEDURE fixedit(x,w);   REAL x;   INTEGER w;
         BEGIN
             field.Sub(field.Pos,w).Putfix(x,secdec);
             field.Setpos(field.Pos+w);
         END of fixedit;

         PROCEDURE intedit(i,w);   INTEGER i,w;
         BEGIN
             field.Sub(field.Pos,w).Putint(i);
             IF field.Getchar = ' ' THEN
             BEGIN   field.Setpos(field.Pos-1);
                 field.Putchar('0');
             END;
             field.Setpos(field.Pos-1+w);
DECsystem-10 SIMULA Language Handbook, part III           Page 76
5.3 OPERATIONS ON TEXTS


         END of intedit;

         BOOLEAN PROCEDURE adjusted;
         BEGIN
             IF m = 60 THEN
             BEGIN   adjusted:= TRUE;
                 hours:= hours + 1;   m:= 0;
                 IF hours = 24 THEN
                 BEGIN   days:= days + 1;   hours:= 0   END
             END;
             field.Sub(2,6):= "   D  ";
             field.Setpos(5);
             IF days < 1 THEN
             field.Putchar(' ') ELSE
             IF days < 10 THEN
             BEGIN
                 field.Setpos(4);
                 field.Putchar(Char(days+Rank('0')));
             END ELSE
             IF days < 100 THEN
             BEGIN   field.Setpos(3);   intedit(days,2)   END
             ELSE
             IF days < 1000 THEN
             BEGIN   field.Setpos(2);   intedit(days,3)   END
             ELSE
             IF days <= 9999 AND days >= -999 THEN
             BEGIN   field.Setpos(1);   intedit(days,4)   END
             ELSE
             field.Sub(1,4):= "****";
             field.Setpos(8);
             intedit(hours,2);   field.Putchar(':');
         END of adjust;

         powersec:= 1;
         FOR m:= 1 step 1 UNTIL secdec DO powersec:= powersec*10;
         IF unit = 'D' THEN time:= 1440*time ELSE
         IF unit = 'H' THEN time:= 60*time ELSE
         IF unit = 'M' THEN ELSE
         IF unit = 'S' THEN time:= time/60 ELSE
         BEGIN   putfloat(field,time);
             GO TO stop
         END;

         field.Setpos(1);
         field.Putchar(IF time < 0 THEN '-' ELSE ' ');
         time:= Abs(time);
         IF time > 34 359 738 367 THEN GO TO error;
         m:= Entier(time);
         seconds:= 60*(time - m);
         hours:= m//60;
         m:= Mod(m,60);
         days:= hours//24;
         hours:= Mod(hours,24);
         IF secdec >= 0 THEN
         BEGIN
             IF Entier(seconds*powersec+0.5) = 60*powersec THEN
DECsystem-10 SIMULA Language Handbook, part III           Page 77
5.3 OPERATIONS ON TEXTS


             BEGIN   m:= m + 1;   seconds:= 0   END;
             adjusted;
             intedit(m,2);   field.Putchar('.');
             IF seconds < 9.5 THEN
             BEGIN   field.Putchar('0');
                 fixedit(seconds,
                 IF secdec = 0 THEN 1 ELSE secdec+2)
             END ELSE
             fixedit(seconds,IF secdec = 0 THEN 2 ELSE secdec+3);
         END ELSE
         BEGIN   time:= m + seconds/60;
             m:= time;
             IF adjusted THEN time:= 0;
             IF time < 9.5 THEN   field.Putchar('0');
             secdec:= 0;
             fixedit(time,IF time < 9.5 THEN 1 ELSE 2)
         END;
         stop:
         field.Setpos(1);   puttime:- field
     END of puttime OK ELSE
     error:
     BEGIN   field.Setpos(1);
         puttime:- putfloat(field,time);
     END of puttime error;


**** TEXT PROCEDURE putfloat(t,x);   TEXT t;   REAL x;

     PROCEDURE PUTFLOAT edits a number X into the text T (right
     justified).

     Insignificant trailing zeros in fractions are removed.

     Representation errors (of type 98.9999999) are corrected.
     If fixed point format cannot be used (displaying significant
     digits), floating point format is used instead.  The output
     will depend on the length of the text T.  A value in the
     range [8,16] is recommended.

     PUTFLOAT also returns a reference to the text parameter.

     TEXT PROCEDURE putfloat(t,x);   TEXT t;   REAL x;
     BEGIN   INTEGER w;

         w:= t.Length;   t:= NOTEXT;

         IF w = 0 THEN ! NOTEXT !; ELSE
         IF x = 0 THEN t.Sub(w,1).Putchar('0') ELSE
         BEGIN   REAL saved;   BOOLEAN negative;
             INTEGER d,i,pow,j;

             negative:= x < 0;   d:= 8;  ! No. of sign. digits;
             saved:= x;   x:= Abs(x);

             IF x >= &8 OR x < &-7 THEN
             realedit:
DECsystem-10 SIMULA Language Handbook, part III           Page 78
5.3 OPERATIONS ON TEXTS


             BEGIN   pow:= 0;
                 WHILE x >= 10 DO
                 BEGIN   x:= x*0.1;   pow:= pow + 1   END;
                 WHILE x < 1 DO
                 BEGIN   x:= x*10;    pow:= pow - 1   END;
                 ! Calculate length for exp part;
                 j:= IF pow >= 10 THEN 3 ELSE
                     IF pow >=  0 THEN 2 ELSE
                     IF pow >= -9 THEN 3 ELSE 4;

                 i:= w - j;
                 IF i > (IF negative THEN 1 ELSE 0) THEN
                 BEGIN   CHARACTER low10;   TEXT temp;
                     putfloat(t.Sub(1,i),x*sign(saved));
                     t.Setpos(1);   IF t.Getchar = '*' THEN GO TO
     realcase;
                     temp:- blanks(4); temp.putreal(1,0);
                     temp.Setpos(1);  low10:= temp.getchar;
                     t.Setpos(1);
                     WHILE t.Pos <= i DO
                     IF t.Getchar = low10 THEN GO TO realcase;
                     t.Putchar(low10);
                     t.Sub(i+2,j-1).Putint(pow);
                 END ELSE
                 realcase:
                 BEGIN   i:= w - (IF negative THEN 6 ELSE 5);
                     IF i < 0 THEN i:= 0;
                     IF d > i THEN d:= i;
                     t.Putreal(saved,d)
                 END putreal case
             END realedit block ELSE
             BEGIN   INTEGER pow_d,pow_di,n1,m,di,ix;

                 pow:= 1;
                 pow_di:= pow_d:= 100 000 000;   ! = 10**d;

                 ! Scale x to [0.1,1-eps] ;
                 WHILE x >= 1.0 DO
                 BEGIN   x:= x*0.1;
                     IF pow_di = 1 THEN GO TO realedit;
                     pow_di:= pow_di//10;
                     i:= i - 1
                 END;
                 WHILE x < 0.1 DO
                 BEGIN   x:= x*10;  pow:= pow*10;
                     i:= i + 1
                 END;

                 di:= d + i;
                 IF di < 0 THEN
                 BEGIN   d:= -i;   di:= 0  END;

                 ix:= x*pow_d;   ! IX now integer with full prec;

                 ! Fix 9999.... problem;
                 j:= Mod(ix,100);
DECsystem-10 SIMULA Language Handbook, part III           Page 79
5.3 OPERATIONS ON TEXTS


                 IF j >= 90 THEN ix:= ix + 100 - j ELSE
                 IF j <= 10 THEN ix:= ix - j;

                 n1:= ix//pow_di//pow;       ! =  Integer Part;

                 ! Calculate j = no. of chars before dec. point;
                 m:= n1;   j:= IF negative THEN 2 ELSE 1;
                 WHILE m >= 10 DO
                 BEGIN   m:= m//10;   j:= j + 1   END loop;

                 ix:= ix -(n1*pow_di)*pow;
                 ! ix = fraction ;

                 IF ix NE 0 THEN
                 ! Remove trailing zeros in IX;
                 WHILE Mod(ix,10) = 0 DO
                 BEGIN   ix:= ix//10;   di:= di-1   END mod loop;

                 IF j + (di+1)*Sign(ix) > w THEN GO TO realedit;

                 IF negative THEN n1:= -n1;

                 IF ix = 0 THEN t.Putint(n1) ELSE
                 BEGIN
                     j:= w-di;
                     IF negative AND n1 = 0 THEN
                     t.Sub(j-2,2):= "-0" ELSE
                     t.Sub(1,j-1).Putint(n1);
                     t.Setpos(j);   t.Putchar('.');
                     t.Sub(t.Pos,di).Putint(ix);

                     ! Fill in zeros;
                     WHILE ix > 0 DO
                     BEGIN   ix:= ix//10;  di:= di - 1  END loop;
                     t.Setpos(j+1);
                     FOR j:= 1 STEP 1 UNTIL di DO t.Putchar('0');

                 END fraction present
             END w > 0
         END x not = 0;
         putfloat:- t
     END of putfloat;


**** INTEGER PROCEDURE scan(command,n,arg,key,defaultkey);
     TEXT command;   INTEGER n;
     TEXT ARRAY arg,key;   INTEGER defaultkey;

     Integer procedure SCAN will identify specified KEYs in a
     COMMAND text string.  SCAN performs - in order -
DECsystem-10 SIMULA Language Handbook, part III           Page 80
5.3 OPERATIONS ON TEXTS


     1.  Does COMPRESS and UPCASE on the COMMAND string

     2.  If the parm.  DEFAULTKEY belongs to [1:N] and COMMAND
         string does not start with the text KEY[DEFAULTKEY] then
         that key will be assumed present in front of COMMAND.

     3.  Locates (in order 1 to N) possible occurrences of the
         texts defined in text array KEY[1:N].

     4.  Makes ARG[x] :- whatever follows KEY[x] up to next KEY.
         If the KEY is just present, but with no text following
         then Blanks(1) is returned.  Nonpresent KEY is indicated
         with ARG[x] == NOTEXT.

     5.  SCAN returns index for multiple used key in command
         string.  Thus, normally SCAN should return zero,
         indicating no multiple used key.


     Note that the contents of KEY must have Upper case letters
     only.
     An example:
     !       BEGIN
     !           EXTERNAL TEXT PROCEDURE conc,upcase,compress,
     !           rest,inline,checkextension;
     !           EXTERNAL CHARACTER PROCEDURE findtrigger;
     !           EXTERNAL INTEGER PROCEDURE search,scanint,scan;
     !           EXTERNAL REF (Infile) PROCEDURE findinfile;
     !           EXTERNAL REF (Outfile) PROCEDURE findoutfile;
     !       
     !           TEXT ARRAY key,arg,default[1:6];
     !           TEXT command,infilename,outfilename;
     !           INTEGER avalue,index;
     !           BOOLEAN na,nb;
     !           REF (Infile) inf;
     !           REF (Outfile) outf;
     !       
     !           key[1]:- Copy("/DEFAULT:/A:/NA/NB/N=");
     !           ! Save some space with this trick!;
     !           key[2]:- key[1].Sub(10,3);  !/A: ;
     !           key[3]:- key[1].Sub(13,3);  !/NA ;
     !           key[4]:- key[1].Sub(16,3);  !/NB ;
     !           ! This keyword (5) must come after /NA and /NB
     !           ! else it will swamp those keys (if present);
     !           key[5]:- key[1].Sub(19,2);  !/N  ;
     !           key[6]:- key[1].Sub(21,1);  !=   ;
     !           key[1]:- key[1].Sub(1,9);   !/DEFAULT: ;
     !       
     !           start:
     !           FOR index:= scan(inline("*",Sysin),6,arg,key,1)
     !           WHILE index NE 0 DO
     !           BEGIN   Outtext("? Keyword:");
     !               Outtext(key[index]);
     !               Outtext(" used more than once.");
     !               Outtext(" Please try again.");
     !               Outimage;
DECsystem-10 SIMULA Language Handbook, part III           Page 81
5.3 OPERATIONS ON TEXTS


     !           END loop;
     !       
     !           ! Analyze result:;
     !           ! Assume the user entered: abc=def/A:12/N  ;
     !           ! The result will then be:
     !           ! arg[1] = "ABC"
     !           ! arg[2] = "12"
     !           ! arg[3] == NOTEXT
     !           ! arg[4] == NOTEXT
     !           ! arg[5] = " "
     !           ! arg[6] = "DEF"
     !           ;
     !       
     !           ! Test file information;
     !           ! Default inputname is outputname;
     !           IF arg[6] == NOTEXT THEN arg[6]:- arg[1];
     !           infilename:- arg[6];
     !       
     !           ! We also demonstrate a way of checking
     !           ! entered file specifications;
     !           IF infilename NE "TTY:" THEN
     !           BEGIN
     !               infilename:-
     !               checkextension(infilename,".EXT");
     !               FOR inf:- findinfile(infilename) WHILE
     !               inf == NONE DO
     !               BEGIN   Outtext("? Cannot find Infile:");
     !                   Outtext(infilename);
     !                   Outimage;
     !                   infilename:-
     !                   inline("Enter name of infile:",Sysin);
     !                   infilename:-
     !                   checkextension(infilename,".EXT");
     !               END loop;
     !           END not TTY ELSE
     !           inf:- Sysin;
     !       
     !           outfilename:- arg[1];
     !           IF outfilename NE "TTY:" THEN
     !           BEGIN
     !               outfilename:-
     !               checkextension(outfilename,".EXT");
     !               FOR outf:-
     !               findoutfile(outfilename)  WHILE outf ==
     !               NONE DO
     !               BEGIN
     !                   Outtext("? Cannot create Outfile:");
     !                   Outtext(outfilename);
     !                   Outimage;
     !                   outfilename:-
     !                   inline("Enter name of outfile:",Sysin);
     !                   outfilename:-
     !                   checkextension(outfilename,".EXT");
     !               END loop
     !           END ELSE outf:- Sysout;
     !       
DECsystem-10 SIMULA Language Handbook, part III           Page 82
5.3 OPERATIONS ON TEXTS


     !           ! Check value switch /A: ;
     !           IF arg[2] == NOTEXT THEN
     !           BEGIN   !.... Set default value arg[2]:- ... ;
     !           END;
     !           avalue:= scanint(arg[2]);
     !           ! Assume range [1,99];
     !           ! Check result, Pos = 1 is unsuccessful
     !           deediting, More indicates
     !           ! superfluous information in value;
     !           IF avalue < 0 OR avalue > 99 OR arg[2].Pos = 1
     !           OR arg[2].More THEN
     !           BEGIN   Outtext("? Illegal /A: value:");
     !               Outtext(arg[2]);
     !               Outimage;
     !               GO TO start;
     !           END;
     !       
     !           ! Assume  /N short for /NA ;
     !           IF arg[3] == NOTEXT THEN arg[3]:- arg[5];
     !           na:= arg[3] =/= NOTEXT;
     !           ! More strict: IF arg[3] = " " THEN na:= TRUE
     !           ELSE Error;
     !           ! Error would indicate the string
     !           "/NAxxx/....";
     !       
     !           nb:= arg[4] =/= NOTEXT;
     !       
     !           !....;
     !       
     !       END of program

     EXTERNAL Procedures required:
     TEXT PROCEDURE conc,upcase,compress;
     INTEGER PROCEDURE search;

     IF n < 1 THEN
     BEGIN  IF Pos > 1 THEN Outimage;
         Outtext("%SCAN - Illegal parm! N < 1.");
         Outimage
     END ELSE
     BEGIN
         INTEGER ARRAY keypos[1:n];   INTEGER i,j,posmin,keyposi;

         OPTIONS(/A);   arg[1]:- arg[n];   key[1]:- key[1];
         key[n]:- key[n];;   OPTIONS(/-A);
         command:- compress(command,' ');
         upcase(command);
         IF defaultkey > 0 AND defaultkey <= n THEN
         BEGIN
             IF (IF command.Length < key[defaultkey].Length
             THEN TRUE
             ELSE command.Sub(1,key[defaultkey].Length)
             NE key[defaultkey] ) THEN
             command:- conc(key[defaultkey],command);
         END default key ELSE command:- Copy(command);
DECsystem-10 SIMULA Language Handbook, part III           Page 83
5.3 OPERATIONS ON TEXTS


         FOR i:= 1 STEP 1 UNTIL n DO
         BEGIN
             command.Setpos(1);
             j:= search(command,key[i]);
             IF j <= command.Length THEN
             BEGIN
                 command.Sub(j,key[i].Length):= NOTEXT;
                 keypos[i]:= j;
                 command.Setpos(j+key[i].Length);
                 IF search(command,key[i]) <= command.Length THEN
                 BEGIN  scan:= i;   GO TO exit;   END mult key;
             END key found
         END i loop;

         FOR i:= 1 STEP 1 UNTIL n DO
         IF keypos[i] > 0 THEN
         BEGIN
             keyposi:= keypos[i];
             ! Search smallest keypos[j] > keypos[i];
             posmin:= command.Length + 1;
             FOR j:= 1 STEP 1 UNTIL n DO
             IF keypos[j] > keyposi THEN
             BEGIN
                 IF keypos[j] < posmin THEN posmin:= keypos[j];
             END j loop;

             j:= keyposi + key[i].Length;
             arg[i]:- IF posmin = j THEN Blanks(1) ELSE
             command.Sub(j,posmin-j);
         END keypos[i] > 0 ELSE arg[i]:- NOTEXT;

         exit:
     END of scan;


**** SSCAN
     is a version of SCAN used by GETVIS (see chapter 1).
     SSCAN accepts swedish letters and does not zero the "arg"
     array
     for unused switches.


**** DECOM
     is a package to simplify the writing of SIMULA programs
     which accept input in the conventional DEC-10 format:

     OUTFIL.EXT/SWITCH1/SWITCH2...=INFIL.EXT/SWITCH3...

     DECOM is a subclass of SAFMIN (See SAFEIO).

     Files: DECOM.SIM and DECOM.HLP. DECOM.ATR and DECOM.REL are
     included in LIBSIM.

     Written by Jacob Palme and Mats Ohlin, Swedish National
     Defense
     Research Institute.
DECsystem-10 SIMULA Language Handbook, part III           Page 84
5.3 OPERATIONS ON TEXTS


**** TEXT PROCEDURE radix(base,i);  INTEGER base,i;

     TEXT PROCEDURE RADIX returns a text containing the
     representation of input I in radix BASE.  BASE may be
     negative but not -1 or zero.  Resulting text will never
     contain blanks.  If BASE = 16 then sequence 0123456789ABCDEF
     will be used, otherwise if BASE > 10 then the sequence
     0123456789(10)(11)(12)...  will be used.

     C.f.  INTEGER PROCEDURE GETRADIX

     Author:  Mats Ohlin, FOA 1, Fack, S-104 50 STOCKHOLM,
     SWEDEN.  Date:  76-12-10

     IF i = 0 THEN radix:- Copy("0") ELSE
     IF base = 0 OR base = -1 OR base = 1 THEN radix:- Copy("*")
     ELSE
     BEGIN   INTEGER j,ndig,abase;   BOOLEAN neg;
         TEXT t;   REF (dig) xdig;

         CLASS dig(c);   CHARACTER c;
         BEGIN   REF (dig) next;
             next:- xdig;   xdig:- THIS dig;
             ndig:= ndig + 1;
         END dig;

         abase:= base*Sign(base);
         IF base > 0 THEN neg:= i < 0;
         IF neg THEN i:= -i;
         WHILE i NE 0 DO
         BEGIN   j:= Mod(i,base);
             IF j < 0 THEN
             BEGIN   j:= j - base;   i:= i + base  END;
             ! 48 = '0'    55 + 10 = 'A' ;
             IF j <= 9 THEN NEW dig(Char(j+48)) ELSE
             IF abase = 16 THEN NEW dig(Char(j+55)) ELSE
             BEGIN   NEW dig(')');
                 WHILE j NE 0 DO
                 BEGIN   NEW dig(Char(Mod(j,10)+48));
                        j:= j//10
                 END;
                 NEW dig('(');
             END unusual base;
             i:= i//base;
         END loop;
         IF neg THEN NEW dig('-');
         t:- Blanks(ndig);
         WHILE xdig =/= NONE DO
         BEGIN   t.Putchar(xdig.c);   xdig:- xdig.next  END;
         t.Setpos(1);
         radix:- t
     END of radix;
DECsystem-10 SIMULA Language Handbook, part III           Page 85
5.3 OPERATIONS ON TEXTS


**** INTEGER PROCEDURE getradix(base,t);
     INTEGER base;   TEXT t;

     INTEGER PROCEDURE GETRADIX converts a text T containing
     an item in base BASE to the corresponding base-10 integer.

     If BASE <= 10 only the characters 012...(BASE-1) may be
     used.
     If BASE = 16 or -16 then the char:s 0..9 A..F may be used.
     For all other bases the sequence should be written:
     01...9(10)(11)(12)....
     Note that texts containing illegal characters will
     always be (somehow) interpreted.

     C.f. TEXT PROCEDURE RADIX.

     Author: Mats Ohlin, FOA 1, Fack, S-104 50 STOCKHOLM, SWEDEN.
     Date: 76-12-10

     EXTERNAL Procedures required:
     CHARACTER PROCEDURE fetchar;
     TEXT PROCEDURE from;

     IF t = "0" THEN error: getradix:= 0 ELSE
     IF base > 1 OR base < -1 THEN
     BEGIN   INTEGER sum,b,i,flag;   CHARACTER c;
     BOOLEAN neg,signflag;

         ! Skip leading blanks and sign;
         FOR c:= fetchar(t,1) WHILE c = ' ' OR c = '+'
         OR c = '-' DO
         BEGIN   t:- from(t,2);
             IF c = '-' OR c = '+' THEN
             BEGIN   neg:= c = '-';
                 IF signflag THEN GO TO error;
                 signflag:= TRUE;
             END sign;
         END c loop;

         ! Check first char;
         IF (IF c = '(' OR Digit(c) THEN TRUE
         ELSE 'A' <= c AND c <= 'F' AND (base = 16 OR
         base = -16) ) THEN
         BEGIN
             ! See how long the item is;
             t.Setpos(1);
             WHILE t.More DO
             BEGIN   c:= t.Getchar;
                 IF Digit(c) THEN !ok; ELSE
                 IF c = '(' THEN flag:= flag + 1 ELSE
                 IF c = ')' THEN flag:= flag - 1 ELSE
                 IF 'A' <= c AND c <= 'F' AND (base = 16 OR
                 base = -16) THEN ! OK; ELSE
                 GO TO endoft;
                 IF flag < 0 THEN GO TO endoft ELSE
                 IF flag > 1 THEN
DECsystem-10 SIMULA Language Handbook, part III           Page 86
5.3 OPERATIONS ON TEXTS


                 BEGIN   t.Setpos(t.Pos-2);
                 GO TO endoft   END;

             END more loop;
             endoft:   IF t.More THEN t:- t.Sub(1,t.Pos-1);

             ! Start summation;
             b:= 1;
             FOR i:= t.Length STEP -1 UNTIL 1 DO
             BEGIN
                 c:= fetchar(t,i);
                 IF c NE ')' THEN
                 sum:= sum + b*(Rank(c)-(IF Letter(c) THEN 55
                 ELSE 48)) ELSE
                 BEGIN
                     i:= i - 2;
                     FOR c:= fetchar(t,i)
                     WHILE c NE '(' AND i > 1 DO
                     i:= i - 1;
                     IF i > 0 THEN
                     sum:= sum + b*from(t,i+1).Getint;
                 END (..) ;
                 IF i > 1 THEN b:= b*base;
             END i loop;
             getradix:= sum*(IF neg THEN -1 ELSE 1)
         END starts with ( or Digit
     END of getradix;


**** INTEGER PROCEDURE arrlgd(ta);
     TEXT ARRAY ta;

     Computes the sum of the lengths of all text array elements
     in TA, plus 1 for each element in the array, allowing for a
     delimiter after each element.  To be used for computing the
     length of the second parameter to ARRTXT (see below).  Part
     of the SIMDBM system.


**** PROCEDURE arrtxt(ta,t,c);
     TEXT ARRAY ta;  TEXT t;  CHARACTER c;

     Copies the contents of all elements of TA to T.  The
     character C is placed after each copied text.  Example:
     TA[1:4] contains "ABC", "X", "123456", "FINISH".  T:-
     Blanks(ARRLGD(TA));  ARRTXT(TA,T,',') will make T =
     "ABC,X,123456,FINISH,".
     Used in the SIMDBM system.
DECsystem-10 SIMULA Language Handbook, part III           Page 87
5.4 INPUT/OUTPUT


5.4 INPUT/OUTPUT

**** CHARACTER PROCEDURE lookahead(fileref);
     REF(Infile COMMENT or Directfile;) fileref;


     Returns the next non-blank character value which would have
     been the result of inchar.  IF lastitem THEN result will be
     blank;

     INSPECT fileref DO
     BEGIN
       IF lastitem THEN lookahead:= ' ' ELSE
       BEGIN lookahead:= inchar; setpos(pos-1);
       END;
     END;


**** PROCEDURE outline(t,out_file); VALUE t;
     TEXT t; REF (outfile) out_file;

     OUTLINE will output the argument text as one or more lines
     on the output device.  Protected against errors when the
     parameter text is longer than the image.
     INSPECT out_file DO
     BEGIN
       WHILE t.length > length DO
       BEGIN
         outtext(t.sub(1,length));
         t:- t.sub(length+1,t.length-length);
         outimage;
       END;
       outtext(t);
       outimage;
     END;


**** PROCEDURE breakoutline(t,out_file); VALUE t;
     TEXT t; REF (outfile) out_file;

     Same as OUTLINE, but does not output any new line indication
     (<CR><LF> on ASCII terminals) before and after the text.
     INSPECT out_file DO
     BEGIN
       WHILE t.length > length DO
       BEGIN
         breakoutimage;
         outtext(t.sub(1,length));
         t:- t.sub(length+1,t.length-length);
       END;
       outtext(t);
       breakoutimage;
     END;
DECsystem-10 SIMULA Language Handbook, part III           Page 88
5.4 INPUT/OUTPUT


**** TEXT PROCEDURE inline(question,inf);   NAME question;
     TEXT question;   REF (infile) inf;

     Returns a stripped copy of a new INF input line
     after displaying QUESTION on Sysout.

     INSPECT (IF inf == NONE THEN Sysin ELSE inf) DO
     BEGIN   Sysout.Outtext(question);
         Sysout.Breakoutimage; Inimage;
         inline:- Copy(Image.Strip);
         Setpos(0);
     END;



**** TEXT PROCEDURE request
     (prompt,default,result,valid,errmessage,help);
         NAME prompt,default,result,valid,errmessage,help;
         TEXT prompt,default,result,errmessage,help;
         BOOLEAN valid;

     Procedure REQUEST may be used when putting simple questions
     to an interactive user.  The PROMPTing question and the
     DEFAULT value will be displayed on the user's terminal
     (SYSOUT).  The Stripped input line from the terminal (SYSIN)
     is stored in RESULT.  If then the NAME parameter VALID is
     TRUE the result is accepted and (also) returned through
     REQUEST.  Otherwise the ERRMESSAGE is displayed followed by
     a new PROMPTing question.  If the user enters an empty
     answer - i.e.  presses the return key - the DEFAULT answer
     will be used.  (This may be prohibited by using an illegal
     answer for default.) If the user enters a question mark '?',
     the text HELP will be printed.  Since it is a NAME
     parameter, actual parameter may be a text procedure call
     with the possible side effect of displaying additional help
     text.

     Since it may be difficult the remember the different
     parameters - learn the following sentence:  Please ( P for
     Prompt) Don't (D for Default) Risk (R for Result) Villainous
     (V for Valid) Entries (E for Errmessage) Here (H for Help).

     Example:
     !BEGIN EXTERNAL TEXT PROCEDURE conc,request,rest;
     !    EXTERNAL REF (Infile) PROCEDURE findinfile;
     !    EXTERNAL INTEGER PROCEDURE checkreal;
     !
     !    TEXT u;    REAL x;
     !
     !    request("File:",NOTEXT,u,
     !    findinfile(u)=/=NONE,conc("? Can't find:",u),
     !    "Enter valid file spec for input file.");
     !
     !    x:=
     !    request("Enter x:","2.5",u,
     !    checkreal(u) = 1 AND rest(u).Strip == NOTEXT,
DECsystem-10 SIMULA Language Handbook, part III           Page 89
5.4 INPUT/OUTPUT


     !    "?Illegal real item.","Enter valid real item").Getreal;
     !
     !END

     ! For more frequent applications it is recommended to use
     ! a special validity testing Boolean procedure with the
     ! side-effect of saving (the finally correct) result.
     ! I.e.
     ! EXTERNAL TEXT PROCEDURE rest,request;
     ! EXTERNAL LONG REAL PROCEDURE scanreal;
     !
     ! BOOLEAN PROCEDURE testreal(u,x);
     ! NAME x;   TEXT u;   REAL x;
     ! BEGIN   INTEGER p;
     !     p:= u.Pos;   x:= scanreal(u);
     !     testreal:= IF u.Pos > p THEN rest(u).Strip == NOTEXT
     !                ELSE FALSE;
     ! END of testreal;
     !
     !    request("Enter x:","2.5",u,testreal(u,x),
     !    "?Illegal real item.","Enter valid real item");

     TEXT PROCEDURE request
     (prompt,default,result,valid,errmessage,help);
     NAME prompt,default,result,valid,errmessage,help;
     TEXT prompt,default,result,errmessage,help;
     BOOLEAN valid;
     BEGIN   TEXT t;

         GO TO start;

         WHILE NOT valid DO
         BEGIN
             Outtext(errmessage);   Outimage;
             start:
             Outtext(prompt);
             IF default =/= NOTEXT THEN
             BEGIN   Outchar('/');   Outtext(default);
                 Outchar('/');   Outchar(':')
             END;
             Breakoutimage;   Inimage;
             t:- Copy(Sysin.Image.Strip);   Sysin.Setpos(0);
             IF t == NOTEXT THEN result:- Copy(default) ELSE
             IF t.Getchar = '?' THEN
             BEGIN   Outtext(help);   Outimage;
                 GO TO start
             END ELSE
             BEGIN   t.Setpos(1);   result:- t   END;
         END loop;

         request:- result

     END of request;
DECsystem-10 SIMULA Language Handbook, part III           Page 90
5.4 INPUT/OUTPUT


**** PROCEDURE outtime(file,time,unit,secdec,fieldwidth);
     REAL time;   CHARACTER unit;   INTEGER secdec,fieldwidth;  
     REF (Outfile) file;

     Prints the variable TIME on the outfile FILE according
     to PUTTIME format. C.f. procedure PUTTIME.
     EXTERNAL PROCEDURES required:
     TEXT PROCEDURE putfloat, puttime;


**** PROCEDURE histp(a,lowerbound,upperbound,yscale,
     max,min,brick,xlabels,title,pf);
     NAME title,xlabels;  VALUE brick;
     INTEGER ARRAY a;
     INTEGER lowerbound,upperbound,yscale,max,min;
     TEXT brick,xlabels,title;  REF (Outfile) pf;

     Procedure HISTP prints a histogram of the INTEGER ARRAY A
     [LOWERBOUND:UPPERBOUND] on file PF.

     YSCALE is the increment for the y axis (Integer > 0).
     MAX is the maximum y value displayed (INTEGER).
     MIN is the minimum y value displayed (INTEGER).

     BRICK is a text which will be used when printing histogram
     "piles" (TEXT by VALUE).

     XLABELS is a text that will be printed at the bottom of the
     histogram.  If XLABELS == NOTEXT the indices LOWERBOUND and
     UPPERBOUND will be printed.  The start of the text will be
     at the first "brick" character of the first "pile".

     TITLE is a text that will be printed at the top of the
     histogram.

     PF is the output file.  If PF is a PRINTFILE, HISTP will
     start by calling EJECT(1).

     Please note the following HISTP properties:



     1.  If MAX < MIN, the MAX and MIN values will be adjusted if
         necessary (individually!).  Thus, if MAX = -1 and MIN =
         0 an array A with only positive elements will be
         presented in a histogram with y axis range [0:max of A].

     2.  If (resulting) MIN is zero, this level will be indicated
         by the x axis (----).

     3.  If BRICK starts with a blank, a single space between
         "piles" will be printed.

     4.  IF PF == NONE, Sysout will be used.

     5.  IF the range [LOWERBOUND:UPPERBOUND] in combination with
DECsystem-10 SIMULA Language Handbook, part III           Page 91
5.4 INPUT/OUTPUT


         actual BRICK.LENGTH cannot be printed on one page
         regarding current PF.Length, then the rest (the
         rightmost part) of the histogram will be printed on a
         subsequent page.


     An example:

     Input:

     A[0:6]:=  5 -3 -1 0 3 4 2
     YSCALE:=  1
     MAX:=     -10
     MIN:=      10
     BRICK:=   " ***"
     XLABELS:=  "  A   B   C   D   E   F   G"
     TITLE:=    "Test example - histogram print"
     PF:-       NONE

        will produce the following output on SYSOUT:

                  Test example - histogram print

                5 ! ***
                  ! ***                 ***
                  ! ***             *** ***
                  ! ***             *** *** ***
                1 ! ***             *** *** ***
                  !----------------------------
                  !     *** ***
                  !     ***
               -3 !     ***
                   --+---+---+---+---+---+---+-
                     A   B   C   D   E   F   G

     IF lowerbound > upperbound THEN
     BEGIN   Outtext("?HISTP Illegal Array Bounds");   Outimage 
     END
     ELSE IF yscale <= 0 THEN
     BEGIN   Outtext("?HISTP Non-positive Y-scale element");  
     Outimage   END
     ELSE
     BEGIN
         INTEGER i,up,newupperbound,h2,
         tempmax,tempmin,width,negscale;
         TEXT axis;

         width:= brick.Length;
         axis:- Blanks(width);
         WHILE axis.More DO axis.Putchar('-');
         IF pf == NONE THEN pf:- Sysout;

         IF max < min THEN
         BEGIN   tempmin:= tempmax:= a[lowerbound];
             FOR i:= lowerbound+1 STEP 1 UNTIL upperbound DO
             IF a[i] > tempmax THEN tempmax:= a[i] ELSE
DECsystem-10 SIMULA Language Handbook, part III           Page 92
5.4 INPUT/OUTPUT


             IF a[i] < tempmin THEN tempmin:= a[i];
             IF max < tempmax THEN max:= tempmax;
             IF min > tempmin THEN min:= tempmin;
         END loop setting max and min;

         h2:= (max+min)//2;

         IF (upperbound - lowerbound + 1)*width + 15 > pf.Length
         THEN
         BEGIN   newupperbound:= upperbound;
             upperbound:= (pf.Length-15)//width + lowerbound - 1
         END
         ELSE newupperbound:= lowerbound - 1;
         ! That was checking histogram width;

         INSPECT pf WHEN Printfile DO
         BEGIN   Eject(1);   Setpos(14);   Outtext(title);
             Outimage;   Eject(Line+2)
         END
         WHEN Outfile DO
         BEGIN   Setpos(14);   Outtext(title);
             Outimage;   Outimage
         END;

         up:= ((h2-min)//yscale)*yscale + min;
         IF up < h2 THEN up:= up + yscale;   h2:= up;
         up:= ((max-min)//yscale)*yscale + min;
         IF up < max THEN up:= up + yscale;

         pf.Outint(up,12);   pf.Outtext(" !");
         negscale:= - yscale;
         FOR up:= up STEP negscale UNTIL min DO
         IF NOT (up = min AND min = 0) THEN
         BEGIN
             IF up = h2 OR up = min THEN
             BEGIN   pf.Setpos(1);   pf.Outint(up,12);
                 pf.Outtext(" !")
             END
             ELSE
             BEGIN   pf.Setpos(14);   pf.Outchar('!')   END;

             IF up NE 0 THEN
             BEGIN
                 FOR i:= lowerbound STEP 1 UNTIL upperbound DO
                 IF a[i] = up THEN pf.Outtext(brick) ELSE
                 IF a[i] > up EQV up >= 0 THEN pf.Outtext(brick)
                 ELSE pf.Setpos(pf.Pos+width);
             END ne 0 ELSE
             IF min < 0 THEN
             BEGIN   pf.Setpos(14);   pf.Outchar('!');
                 FOR i:= lowerbound STEP 1 UNTIL upperbound DO
                 pf.Outtext(axis);
             END zero axis;

             pf.Outimage
DECsystem-10 SIMULA Language Handbook, part III           Page 93
5.4 INPUT/OUTPUT


         END print loop;

         pf.Setpos(15);
         FOR i:= lowerbound STEP 1 UNTIL upperbound DO
         pf.Outtext(axis);
         i:= (upperbound-lowerbound)*width+15+width//2;
         IF width > 1 THEN
         BEGIN
             FOR h2:= 15+width//2 STEP width UNTIL i DO
             BEGIN   pf.Setpos(h2);   pf.Outchar('+')   END;
         END;
         pf.Outimage;
         IF xlabels == NOTEXT THEN
         BEGIN
             pf.Outint(lowerbound,15+width//2);
             IF i > pf.Length THEN i:= pf.Length - 4;
             pf.Setpos(i-4);   pf.Outint(upperbound,5);
         END ELSE
         BEGIN   pf.Setpos(15);   pf.Outtext(xlabels)   END;
         pf.Outimage;
         IF newupperbound >= upperbound THEN
         histp(a,upperbound+1,newupperbound,yscale,max,min,
         brick,xlabels,title,pf);

     END of histp;
DECsystem-10 SIMULA Language Handbook, part III           Page 94
5.5 SORTING AND SUMMATION ETC.


5.5 SORTING AND SUMMATION ETC.



**** INTEGER PROCEDURE ilog(x);  REAL x;
     ilog:= IF x = 0 THEN 0 ELSE
     Entier(Ln(Abs(x))/2.30258 509517)+1;



**** INTEGER PROCEDURE isum(ia,n);
     INTEGER ARRAY ia;   INTEGER n;

     Procedure ISUM calculates the sum of the integer array IA:
     IA[1] + ... + IA[N].

     BEGIN   INTEGER i,s;

         OPTIONS(/A); COMMENT START ARRAY BOUND CHECKING;
         s:= ia[1];
         ia[n]:= ia[n];;
         OPTIONS(/-A); COMMENT NO ARRAY BOUND CHECKING;
         FOR i:= 2 STEP 1 UNTIL n DO  s:= s + ia[i];

         isum:= s

     END of isum;


**** REAL PROCEDURE rsum(a,n);   ARRAY a;   INTEGER n;

     Procedure RSUM calculates the sum of the array A:
     A[1] + ... + A[N].

     BEGIN   INTEGER i;   REAL s;

         OPTIONS(/A); COMMENT START ARRAY BOUND CHECKING;
         s:= a[1];   a[n]:= a[n];;
         OPTIONS(/-A); COMMENT NO ARRAY BOUND CHECKING;
         FOR i:= 2 STEP 1 UNTIL n DO  s:= s + a[i];

         rsum:= s

     END of rsum;


**** LONG REAL PROCEDURE lsum(la,n);
     LONG REAL ARRAY la;   INTEGER n;

     Procedure LSUM calculates the sum of the long real array LA,
     LA[1] + ... + LA[N] (almost) preserving precision.  Thus if
     LA[1] = E30, LA[2] = 1 and LA[3] = -E30 the sum will be
     correctly calculated to 1.
     EXTERNAL Procedure required: INTEGER PROCEDURE intrea;

     BEGIN   INTEGER i,icell,high,low;   LONG REAL s;
DECsystem-10 SIMULA Language Handbook, part III           Page 95
5.5 SORTING AND SUMMATION ETC.


         LONG REAL ARRAY cell[0:63];

         OPTIONS(/A); COMMENT START ARRAY BOUND CHECKING;
         la[n]:= la[n];

         icell:= intrea(la[1])//8R4000000000;;
         OPTIONS(/-A); COMMENT NO ARRAY BOUND CHECKING;
         IF icell < 0 THEN icell:= -icell;
         high:= low:= icell;
         cell[icell]:= la[1];
         FOR i:= 2 STEP 1 UNTIL n DO
         BEGIN   icell:= intrea(la[i])//8R4000000000;
             ! Store LA[I] in CELL [ Abs(exp-part of LA[I]) ];
             ! Thus E+MM and -E+MM will be accumulated in the
             ! same cell;
             IF icell < 0 THEN icell:= -icell;
             IF icell > high THEN high:= icell ELSE
             IF icell < low THEN low:= icell;
             cell[icell]:= cell[icell] + la[i];
         END loop;

         ! Sum starting with small values;
         FOR i:= low STEP 1 UNTIL high DO
         s:= s + cell[i];
         lsum:= s

     END of lsum;


**** REAL PROCEDURE sigma2(mean,sum,a,n);
     NAME mean,sum;   REAL mean,sum;
     ARRAY a;   INTEGER n;

     Real procedure SIGMA2 calculates the variance, mean value
     and sum of a REAL ARRAY A, from A[1] to A[N].  Array A must
     be declared before calling SIGMA2 and have a lower bound <=
     1 and a upper bound >= N.  Results are returned in -

     SIGMA2          Variance
     MEAN            Mean value
     SUM             Sum

     IF n > 0 THEN
     BEGIN   REAL s,s2,x;   INTEGER i;

         OPTIONS(/A); COMMENT START ARRAY BOUND CHECKING;
         s:= a[1];   a[n]:= a[n];;
         OPTIONS(/-A); COMMENT NO ARRAY BOUND CHECKING;
         s2:= s^2;
         FOR i:= 2 STEP 1 UNTIL n DO
         BEGIN   x:= a[i];
             s:= s + x;
             s2:= s2 + x^2;
         END;

         x:= 1/n;
DECsystem-10 SIMULA Language Handbook, part III           Page 96
5.5 SORTING AND SUMMATION ETC.


         sigma2:= (s2 - s^2*x)*x;
         mean:= s*x;
         sum:= s;
     END of sigma2;


**** PROCEDURE sigmean(sigma2,mean,k,xk1);
     NAME sigma2,mean,k;   REAL sigma2,mean,xk1;   INTEGER k;

     Procedure SIGMEAN calculates new sigma2 (variance) and mean
     value for a statistical material where the following
     properties are known -

     Old variance                            SIGMA2
     Old mean value                          MEAN
     Number of observations made before      K
     Value of new observation                XK1

     At return the following values are available -

     New variance                            SIGMA2
     New mean value                          MEAN
     Number of observations (=K+1)           K

     An example:

     ! BEGIN
     ! EXTERNAL PROCEDURE sigmean;
     ! REAL sigma2,mean;
     ! INTEGER k;
     ! ....
     ! k:= 0;
     ! mean:= sigma2:= 0;
     ! ...
     ! WHILE ... DO
     ! BEGIN
     !    ... x:= <new observed value>;
     !    sigmean(sigma2,mean,k,x);
     ! END loop;
     ! ...

     Note that some precision will be lost using SIGMEAN,
     compared with the result of calculating the variance and
     mean value from all the observations.  However, since
     SIGMEAN calculates the variance and mean value recursively,
     there is no need to save all the earlier observations in an
     array.

     BEGIN   REAL oldsigma2,oldmean,ik1,z;   INTEGER oldk,k1;

         oldsigma2:= sigma2;
         oldmean:= mean;
         oldk:= k;
         k:= k1:= oldk + 1;
         ik1:= 1.0/k1;
         z:= (oldmean-xk1)*ik1;
DECsystem-10 SIMULA Language Handbook, part III           Page 97
5.5 SORTING AND SUMMATION ETC.


         mean:= xk1 + oldk*z;
         sigma2:= oldk*(oldsigma2*ik1 + z^2);
     END of sigmean;




The sorting procedures SORTTA, SORTTD, SORTIA, SORTID, SORTRA,
     SORTRD, SORTLA, SORTLD may be coded as one external assembly
     module accepting any kind of TEXT, [LONG] REAL or INTEGER
     one-dimensional array.


**** PROCEDURE sortta (arr,n);
     TEXT ARRAY arr;   INTEGER n;

     Procedure SORTTA will sort the contents of the TEXT array in
     ASCENDING order.  Author:  Algorithm 271 CACM 11-65, 5-66.
     Modified by:  Mats Ohlin, FOA 1, S-104 50 STOCKHOLM 80,
     SWEDEN.

     BEGIN   INTEGER i,k,q,m,p;   TEXT t,x;
       INTEGER ARRAY ut,lz [1:Ln(Abs(n)+2)/0.69314718];

       OPTIONS(/A); COMMENT START ARRAY BOUND CHECKING;
       IF arr[1] > arr[n] THEN
       BEGIN ; OPTIONS(/-A);
         t:- arr[1];
         arr[1]:- arr[n];   arr[n]:- t
       END test and swap;

       i:= m := 1;
       WHILE m > 0 DO
       BEGIN
         IF n-i > 1 THEN
         BEGIN
           p:= (n+i)//2;    t:- arr[p];
           arr[p]:- arr[i];   q:= n;   k:= i;
           FOR k:= k+1 WHILE k <= q DO
           BEGIN
             IF arr[k] > t THEN
             BEGIN
               WHILE q >= k DO
               BEGIN
                 IF arr[q] < t THEN
                 BEGIN
                   x:- arr[k];   arr[k]:- arr[q];
                   arr[q]:- x;   q:= q-1;
                   GO TO l;
                 END;
                 q:= q-1;
               END Q;
             END;
             l:
           END K;
           arr[i]:- arr[q];
DECsystem-10 SIMULA Language Handbook, part III           Page 98
5.5 SORTING AND SUMMATION ETC.


           arr[q]:- t;
           IF 2*q>i+n THEN
           BEGIN
             lz[m]:= i;   ut[m]:= q-1;
             i:= q+1;
           END ELSE
           BEGIN
             lz[m]:= q+1;   ut[m]:= n;
             n:= q-1;
           END;
           m:= m+1;
         END ELSE
         BEGIN
           IF (
           IF i < n THEN arr[i] > arr[n] ELSE FALSE
           ) THEN
           BEGIN
             x:- arr[i];   arr[i]:- arr[n];
             arr[n]:- x
           END;
           m:= m-1;
           IF m > 0 THEN
           BEGIN   i:= lz[m];   n:= ut[m]   END;
         END
       END m > 0 loop;
     END SORTTEXT IN ASCENDING ORDER;


**** PROCEDURE sorttd (arr,n);
     TEXT ARRAY arr;   INTEGER n;

     Procedure SORTTD will sort the contents of the TEXT array in
     DESCENDING order.  Author:  Algorithm 271 CACM 11-65, 5-66.
     Modified by:  Mats Ohlin, FOA 1, S-104 50 STOCKHOM 80,
     SWEDEN.  Date:  75-09-19 ;

     BEGIN   INTEGER i,k,q,m,p;   TEXT t,x;
       INTEGER ARRAY ut,lz [1:Ln(Abs(n)+2)/0.69314718];

       OPTIONS(/A); COMMENT START ARRAY BOUND CHECKING;
       IF arr[1] < arr[n] THEN
       BEGIN ; OPTIONS(/-A);
         t:- arr[1];
         arr[1]:- arr[n];   arr[n]:- t
       END test and swap;

       i:= m := 1;
       WHILE m > 0 DO
       BEGIN
         IF n-i > 1 THEN
         BEGIN
           p:= (n+i)//2;    t:- arr[p];
           arr[p]:- arr[i];   q:= n;   k:= i;
           FOR k:= k+1 WHILE k <= q DO
           BEGIN
             IF arr[k] < t THEN
DECsystem-10 SIMULA Language Handbook, part III           Page 99
5.5 SORTING AND SUMMATION ETC.


             BEGIN
               WHILE q >= k DO
               BEGIN
                 IF arr[q] > t THEN
                 BEGIN
                   x:- arr[k];   arr[k]:- arr[q];
                   arr[q]:- x;   q:= q-1;
                   GO TO l;
                 END;
                 q:= q-1;
               END Q;
             END;
             l:
           END K;
           arr[i]:- arr[q];
           arr[q]:- t;
           IF 2*q>i+n THEN
           BEGIN
             lz[m]:= i;   ut[m]:= q-1;
             i:= q+1;
           END ELSE
           BEGIN
             lz[m]:= q+1;   ut[m]:= n;
             n:= q-1;
           END;
           m:= m+1;
         END ELSE
         BEGIN
           IF (
           IF i < n THEN arr[i] < arr[n] ELSE FALSE
           ) THEN
           BEGIN
             x:- arr[i];   arr[i]:- arr[n];
             arr[n]:- x
           END;
           m:= m-1;
           IF m > 0 THEN
           BEGIN   i:= lz[m];   n:= ut[m]   END;
         END
       END m > 0 loop;
     END SORTTEXT IN DESCENDING ORDER;


**** PROCEDURE sortdn(arr,i1,n,key);
     INTEGER ARRAY arr;  INTEGER i1,n,key;

     SORTDN sorts (a section of) the 2-dimensional array
     ARR[2,nmax].  The segment ARR[*,I1] to ARR[*,N] is sorted
     according to KEY in ascending order.  KEY determines which
     column to regard as primary sorting key, and whether to sort
     also on the secondary key, thus:
     KEY = 0:  Sort first on ARR[1,*], then ARR[2,*].
     KEY = 1:  Only sort on ARR[1,*].
     KEY = 2:  Reverse of KEY = 1.
     KEY = 3:  Reverse of KEY = 0.
     KEY < 0 or KEY > 3:  as KEY = 0.
DECsystem-10 SIMULA Language Handbook, part III          Page 100
5.5 SORTING AND SUMMATION ETC.


     ARR[1,i] and ARR[2,i] are always moved as a unit (2 words).
     SORTDN is a modification of SORTIA (q.v.), which is a
     modification by Mats Ohlin, FOA, of Algorithm 271 CACM
     11-65, 5-66.  The SORTDN modification was made by Lars
     Enderin, FOA, for the purpose of sorting UFD and SFD
     directory files under TOPS-10.




**** REAL PROCEDURE scalestep(pmax,pmin,ptics);
     NAME pmax,pmin,ptics;  REAL pmax,pmin;  INTEGER ptics;

     Procedure SCALESTEP calculates values suitable for axis
     design.  PMAX is input max (rough) value and at return
     increased justified max value.  PMIN ditto decreased min
     value.  PTICS is number of increments along axis (Result
     parm.) SCALESTEP is size of axis increment.

     REAL PROCEDURE scalestep(pmax,pmin,ptics);  NAME
     pmax,pmin,ptics;  REAL pmax,pmin;  INTEGER ptics;  BEGIN
     REAL max,min,width,d;  INTEGER n0,n1,pow;

     max:= pmax;  min:= pmin;

     width:= Abs(max - min);  IF width NE 0 THEN BEGIN

             WHILE width > 10 DO     BEGIN width:= width*0.1;
     pow:= pow + 1 END;      WHILE width <= 1 DO     BEGIN
     width:= width*10;  pow:= pow - 1 END;

             !  Normalize width ;    IF width NE Entier(width)
     THEN    width:=         IF width > 8 THEN 10 ELSE IF width >
     1.5 THEN Entier(width+1) ELSE   IF width > 1.25 THEN 1.5
     ELSE 1.25;

             !  Calculate normalized increment ;     d:= IF width
     >= 8.0 THEN 2 ELSE      IF width > 3.5 THEN 1 ELSE IF width
     > 1.6 THEN 0.5 ELSE 0.25;

             !  Now scale normalized increment d ;   WHILE pow >
     0 DO    BEGIN d:= d*10;  pow:= pow - 1 END;     WHILE pow <
     0 DO    BEGIN d:= d*0.1;  pow:= pow + 1 END;

             !  Calculate number of increments ;     n1:=
     Entier(max/d);          IF n1*d < max THEN n1:= n1 + 1;
     n0:= Entier(min/d);

             ptics:= n1 - n0;

             pmax:= n1*d;  pmin:= n0*d;

             scalestep:= d;

     END width NE 0;
DECsystem-10 SIMULA Language Handbook, part III          Page 101
5.5 SORTING AND SUMMATION ETC.


     END of scalestep;


**** BOOLEAN PROCEDURE
     iashift(a,destindex,fromindex,length,zero);  INTEGER ARRAY
     a;  INTEGER destindex,fromindex,length;  BOOLEAN zero;

     IASHIFT moves LENGTH elements of the INTEGER ARRAY A,
     starting at FROMINDEX, to DESTINDEX.  FROMINDEX must be >=
     DESTINDEX.  If ZERO is TRUE, then remaining elements to the
     right of DESTINDEX+LENGTH-1 will be zeroed.  Thus,
     IASHIFT(A,1,1,0,TRUE) will make all elements in the array
     A[1:xx] zero.
     IASHIFT will return TRUE if the operation was successful -
     illegal parameters will cause IASHIFT to return FALSE.

     Assuming accessibility of the lower and upper bounds of the
     array the code would be:

     IF destindex >= a.lower AND destindex <= a.upper AND
     fromindex >= destindex AND fromindex+length <= a.upper+1
     THEN
     BEGIN   INTEGER i;
         IF destindex NE fromindex THEN
         FOR i:= 1 STEP 1 UNTIL length DO
         BEGIN   a[destindex]:= a[fromindex];
             destindex:= destindex + 1;
             fromindex:= fromindex + 1;
         END i loop ELSE
         destindex:= destindex + 1;

         IF zero THEN
         ! Zero the rest of a.
         ! Destindex now = next after last moved element;
         FOR i:= destindex STEP 1 UNTIL a.upper DO
         a[i]:= 0;
         iashift:= TRUE
     END of iashift;


**** INTEGER PROCEDURE imax(i1,i2);  INTEGER i1,i2;
     COMMENT IMAX will replace the calling code by inline code;
     imax:= IF i1 > i2 THEN i1 ELSE i2;


**** INTEGER PROCEDURE imin(i1,i2);  INTEGER i1,i2;
     COMMENT IMIN will replace the calling code by inline code;
     imin:= IF i1 < i2 THEN i1 ELSE i2;
DECsystem-10 SIMULA Language Handbook, part III          Page 102
5.6 RANDOM NUMBER GENERATION ETC.


5.6 RANDOM NUMBER GENERATION ETC.


**** PROCEDURE SCRAMBLE(ia,bottom,top,u);  NAME u;  INTEGER ARRAY
     ia;  INTEGER bottom, top, u;

     The INTEGER ARRAY ia is permuted randomly in the interval
     bottom, top.  The parameter u is the random number seed.


**** CLASS PERGEN(a,n);  INTEGER ARRAY a;  INTEGER n;

     CLASS PERGEN generates all the possible permutations of the
     contents in INTEGER ARRAY a[1:N], one at a time.
     Use:
     REF (pergen) pg;
     pg:- NEW pergen(a,n);
     WHILE pg.cycles < 2 DO
     BEGIN Call(pg);  !  use new permutation END;

     Note that N Must be >= 2.  Also observe that permutations
     are generated systematically and that the order will be
     REVERSED when one N!  cycle is completed.  Thus for N = 2
     then result will be (if A[1]=1, A[2]=2 initially):
     (1 2) (2 1) (2 1) (1 2) (1 2) (2 1) etc.
     The permutations will be generated in such manner that the
     last elements of A will change most slowly.  The attribute
     CYCLES will indicate to which cycle the NEXT permutation
     will belong (after next Call that is).

     Ref:"Generation of permutation sequences", A.D.  Woodall,
     The Computer Journal vol 20, No 4 1977 p 346.
     Modified by:  Mats Ohlin, FOA, Stockholm, Sweden.

     For random permutations see procedure SCRAMBLE.

     External procedure required:  IMAX

         CLASS pergen(a,n);  INTEGER ARRAY a;   INTEGER n;
         BEGIN
             INTEGER p,mp,swpt,i,w,cycles;
             INTEGER ARRAY m,km[2:imax(3,n)],
                             ret[2:imax(2,n)];

             IF n < 2 THEN
             BEGIN
                 Outtext("%PERGEN - 2nd parm N must be >= 2");
                 Outimage;
             END ELSE
             BEGIN

                 OPTIONS(/A);
                 a[1]:= a[1];  a[n]:= a[n];
                 km[n]:= ret[n]:= km[2]:= ret[2];;
                 OPTIONS(/-A);
DECsystem-10 SIMULA Language Handbook, part III          Page 103
5.6 RANDOM NUMBER GENERATION ETC.


                 FOR i:= 4 STEP 2 UNTIL n DO
                 BEGIN   p:= i-1;
                     km[i]:= p;   km[p]:= 2-i;
                 END i loop;

                 GO TO run;
                 start:   Detach;   run:
                 cycles:= cycles + 1;

                 FOR i:= 2 STEP 1 UNTIL n DO ret[i]:= i+1;
                 FOR i:= 4 STEP 2 UNTIL n DO
                 BEGIN   m[i]:= i-1;   m[i-1]:= 2-i
                 END i loop;
                 IF Mod(n,2) NE 0 THEN m[n]:= 1-n;

                 loop:   p:= ret[2];

                 IF p > 3 THEN ret[2]:= 3;
                 Detach;
                 w:= a[1];  a[1]:= a[2];  a[2]:= w;
                 IF p > n THEN GO TO start;

                 mp:= m[p];
                 IF mp < 0 THEN
                 BEGIN  swpt:=  1;  mp:= mp+1  END ELSE
                 BEGIN  swpt:= mp;  mp:= mp-1  END;

                 IF mp = 0 THEN
                 BEGIN
                     m[p]:= km[p];
                     ret[p-1]:= ret[p];   ret[p]:= p+1
                 END ELSE m[p]:= mp;

                 Detach;
                 w:= a[p];  a[p]:= a[swpt];  a[swpt]:= w;
                 GO TO loop;
             END n >= 2
         END of pergen;


**** REAL PROCEDURE RANDOM(a,b);  REAL a,b;

     Returns an uniformly distributed value in the interval (a,b)
     (c.f.  FORTRAN routine random).


**** INTEGER PROCEDURE UNIQUE

     UNIQUE will return increasing integer numbers.
     The returned value will increase with one each jiffy
     (1/50 or 1/60 second).
     The returned value is a number in which  bits 1-11 contain
     the day number since 1977-01-01 (mod 4096) and bits 12-35
     contain time of day in jiffies.
     The sequence will restart (from zero) every 4096th day
     (11 years and 81 days).
DECsystem-10 SIMULA Language Handbook, part III          Page 104
5.6 RANDOM NUMBER GENERATION ETC.


     EXTERNAL PROCEDURE required: INTEGER PROCEDURE gettab;

     BEGIN
     ! Take daynumber after 1977-01-01, put it into bits 0-11
     ! and add no. of jiffies (always < 2^23);
     ! 262144 = 2^18     8388608 = 2^23;
     unique:=
       Mod(gettab(9,43)//262144-43144,4096)*8388608
       + gettab(9,8);
     END of unique;


**** INTEGER PROCEDURE nextrandom(n,u);
     INTEGER n,u;

     Returns the N:th successor to U in the random number
     sequence used by the random generator in the DECsystem-10
     SIMULA system.  N may be negative.  (Ref:  SIMULA Newsletter
     Vol 5(2), may 1977)
DECsystem-10 SIMULA Language Handbook, part III          Page 105
5.7 SIMULA VERSIONS OF SYSTEM CLASSES


     5.7 SIMULA VERSIONS OF SYSTEM CLASSES


**** ZIMSET and ZIMULATION

     ZIMSET and ZIMULATION are two SIMULA classes which include
     simple tracing facilities.  They may be used for educational
     as well as debugging purposes.

     For complete documentation, see FOA Report C10055-M3(E5),
     October 1976, distributed as ZIMULA.MAN.

     A small example:

     BEGIN
         EXTERNAL PROCEDURE abort;
         EXTERNAL TEXT PROCEDURE upcase, conc, puttime,
         putfloat, today, daytime;
         EXTERNAL CLASS zimset,zimulation;

         zimulation BEGIN

             process CLASS a; Passivate;

             traceon("Trace.Log","*");
             ! Start trace on TRACE.LOG;

             setparms('M',0);
             ! Time format: Minutes, no decimal seconds;
             activat(NEW a,"DELAY",5,NONE);
             ! ACTIVATE NEW a DELAY 5;
             activat(NEW a,"AT",8,NONE);
             ! ACTIVATE NEW a AT 8;
             hold(2);
             sqslist;
             reactivat(current,"AT",10,NONE);
             ! REACTIVATE Current AT 10;
             prior_:= TRUE;   activat(NEW a,"AFTER",0,NEW a);
             ! ACTIVATE NEW a AFTER NEW a PRIOR;

         END zimulation

     END of program


     will produce the following output on TRACE.LOG:

*** Trace generated 1976-10-13 at 12:20:35 ***  Trace Codes: All

        00:00.00 (  2)        will be Delayed  to       00:05.00
                 (  3)        will be ACT. AT           00:08.00
                 Main Program Held       00:02.00 to    00:02.00

:---- Scheduled Processes ----
:         Evtime    Title
:       00:02.00    Main Program
DECsystem-10 SIMULA Language Handbook, part III          Page 106
5.7 SIMULA VERSIONS OF SYSTEM CLASSES


:       00:05.00    (  2)
:       00:08.00    (  3)
:---- End of SQS List --------

        00:02.00 Main Program will be ACT. AT           00:10.00
                 Main Program was REACT. from           00:02.00
        00:05.00 (  2)        Passivated
        00:08.00 (  3)        Passivated
?       00:10.00 (  4)        Pass. due to ACT. AFTER Idle (  5)
DECsystem-10 SIMULA Language Handbook, part III          Page 107
6. SWEDISH LANGUAGE TEXT HANDLING AND INPUT/OUTPUT


6.  SWEDISH LANGUAGE TEXT HANDLING AND INPUT/OUTPUT
    -----------------------------------------------

NOTE:  Some of these routines are not yet written.  See the list
     in chapter 0.2, which indicates which routines are not
     available.

     The difference between English and Swedish text handling is
     that the national Swedish letters $(=AA), #(=AE), @(=OE) (in
     lower case }(=aa), {(=ae), `(=oe)) are regarded as letters.
     In addition, underline (_) is regarded as part of an
     identifier (like a digit in this context).

     This table gives the names of Swedish procedures
     corresponding to English procedure described above.

     ENGLISH   SWEDISH

**** LETTER    BOKSTAV
**** LOWCASE   LITENBOKSTAV
**** MENU      MENY
**** UPCASE    STORBOKSTAV
**** GETITEM   TAGORD
**** INITEM    INORD
**** GETTYPE   TAGTYP
DECsystem-10 SIMULA Language Handbook, part III          Page 108
7. UTILITIES SPECIFIC TO DECSYSTEM-10


7.  UTILITIES SPECIFIC TO DECSYSTEM-10
    ----------------------------------


     The utilities in this section are intended for specialized
     use.  If you want to write portable programs, you should
     avoid them, since special hardware or software features are
     explicitly used, e.g. a 36-bit word is assumed.


**** INTEGER PROCEDURE absadr;

     Takes a variable of any type as parameter.  Illegal
     parameters will give a returned value = 0.
     - If the variable is a SIMPLE variable (not an array) of
     type INTEGER, REAL, LONG REAL, CHARACTER or BOOLEAN, the
     address of the first word of the value is returned.
     - If it is a REF variable, a copy of the value is returned,
     i e the address of the object or the value of NONE (an
     illegal address).
     - ABSADR of a TEXT variable returns a standard byte pointer
     to the character BEFORE the first character (7-bit byte) of
     the text value.  If t="ABC",
     LOADBYTE(ABSADR(t),1)=Rank('A').  See LOADBYTE, STOREBYTE,
     ADJPTR.
     - ABSADR of an ARRAY is the address of the array object.
     See [LH2] appendix B for the format of class instances
     (objects) and arrays.  This procedure is intended for highly
     implementation- and machine-dependent applications.  Be very
     careful not to cause a garbage collection between
     computation of an absolute address and its use!


**** INTEGER PROCEDURE adjptr(bp,n);
     INTEGER bp,n;

     Adjusts the standard byte pointer BP by N bytes using the
     ADJBP instruction (KL-10/20 processors only, not KA-10 or
     KI-10).  See hardware documentation.


**** INTEGER PROCEDURE andint(x,y);
     INTEGER x,y;

     Performs bitwise AND function of X,Y.  Example:
     ANDINT(2R1010111,2R1001110)=2R1000110.
DECsystem-10 SIMULA Language Handbook, part III          Page 109
7. UTILITIES SPECIFIC TO DECSYSTEM-10


**** CLASS atrstr;

     ATRSTR implements a data structure and procedures which map
     the structure of an attribute file for an external class or
     procedure.  A structure is set up by calling the load
     procedures of the various component classes, taking
     information from an ATR file.  If the file is a library
     file, the modules can be found and mapped one after the
     other.  Subclasses of ATRSTR can be used e.g. to display the
     structure as pseudo-SIMULA code (see SIMATR).


**** INTEGER PROCEDURE bitfield(w,firstbit,len);
     INTEGER w,firstbit,len;

     Returns the byte of word W starting at FIRSTBIT,
     (0 <= FIRSTBIT <= 35) of length L bits, where L=Abs(LEN).
     L>=0 AND L<36 AND FIRSTBIT+L<=36 must hold.
     Special option:  If LEN < 0, the first bit is regarded as a
     sign bit and extended.

     Examples:  Assume w = 8r123456 701234.  Then
     bitfield(w,9,12) = 8r4567, and
     bitfield(w,9,-12)=8r777777 774567.  The prefix 8r means
     octal radix.


**** BOOLEAN PROCEDURE bitget(w,n);
     INTEGER w,n;

     TRUE if bit 36-n in w is 1;


**** PROCEDURE bitput(w,n,b);
     INTEGER w,n;  BOOLEAN b;

     Bit 36-n of w := IF b THEN 1 ELSE 0;
DECsystem-10 SIMULA Language Handbook, part III          Page 110
7. UTILITIES SPECIFIC TO DECSYSTEM-10


**** INTEGER PROCEDURE boolfunc(f,x,y);
     INTEGER f,x,y;

     Computes one of the 16 possible Boolean functions of two
     variables.  The operation is performed on corresponding bits
     in X and Y.  The function is defined by F (0<=F<=15, taken
     modulo 16 if not in range).
     The following functions are defined:
     F    x  0101
          y  0011
     -----------------------------------
     0       0000    FALSE
     1       0001    x AND y
     2       0010    (NOT x) AND y
     3       0011    y
     4       0100    x AND (NOT y)
     5       0101    x XOR y
     6       0110    x OR y
     7       0111    x OR y
     8       1000    NOT (x OR y) "NOR"
     9       1001    x EQV y
     10      1010    NOT x
     11      1011    x IMP y  (NOT x OR y)
     12      1100    x OR (NOT y)
     13      1101    NOT (x OR y)
     14      1110    NOT (x AND y) "NAND"
     15      1111    TRUE
     -----------------------------------
     Example:  BOOLFUNC(4,5,3)=4 (actually, BOOLFUNC(n,5,3)=n
     always).


**** INTEGER PROCEDURE callmic(micfile,savfile);
     VALUE micfile,savfile;  TEXT micfile,savfile;

     PROCEDURE CALLMIC will enable the SIMULA programmer to do
     almost anything from his (her) SIMULA program.  The use of
     this procedure depends on the existence of the Hatfield MIC
     system residing on the SYS: area.

     The procedure CALLMIC is used in the following manner -

     The user first creates a file MIC.TMP containing ordinary
     DEC-10 commands like .DELETE *.BAK
             .RUN ABC
             .COJOB=A.MIC parm1
             .DO ABCMIC
     etc.

     The call CALLMIC("MIC.TMP","SAV.TMP");  will then use
     MIC.TMP for a MIC run.
DECsystem-10 SIMULA Language Handbook, part III          Page 111
7. UTILITIES SPECIFIC TO DECSYSTEM-10


     The files MICFILE,SAVFILE will - if possible - be deleted at
     return.
     If the file name for the MIC file contains a protection code
     with 1st digit equal to 2 (i.e.  "MIC.TMP<277>"), then the
     MIC execution will be silent.  Note, however, that CALLMIC
     will be unable to delete the file afterwards.  (The message
     "?  MACRO FILE NOT FOUND." will follow at the end of the
     SIMULA program.  Please ignore that message.) Alternatively
     the user may start the MIC file with:  .SILENCE

     If the 2nd parameter =/= NOTEXT the MIC session will end by
     returning to the point of CALLMIC call:  CALLMIC will save
     current program in file SAVFILE and end the MIC session with
     .RUN "SAVFILE".

     Otherwise, if SAVFILE == NOTEXT, no return to the calling
     program will occur.

     !!!!    The same restrictions as for SAVE are valid.  Thus:
     !!!!    Only Sysin and Sysout may be open.
     !!!!    Sysin and Sysout must be the user's TTY.

     Note that you may close Outfiles before calling CALLMIC and
     then open again with "file.ext/access:append".  Infiles are
     more difficult to handle - you may keep count of how many
     lines you have read before closing and then read past the
     part already read after opening again.  Directfiles give no
     problems here of course - just save current Location, close
     and open again after return from CALLMIC.

     A small user example:

     !BEGIN
     !    EXTERNAL PROCEDURE run;
     !    EXTERNAL BOOLEAN PROCEDURE scratchfile,tmpout;
     !    EXTERNAL INTEGER PROCEDURE save,callmic;
     !    EXTERNAL TEXT PROCEDURE inline,conc,tmpnam;
     !    INTEGER rc;
     !    TEXT micfile,savfile;

     !    micfile:- inline("Mic file name:",Sysin);
     !    IF micfile == NOTEXT THEN micfile:- Copy("Mic.tmp");
     !    savfile:- inline("Sav file:",Sysin);

     !    Outtext("End with extra CR");
     !    Outimage;
     !    INSPECT NEW Outfile(micfile) DO
     !    BEGIN
     !       Open(Sysin.Image);
     !       ! Note the neat way of copying input lines
     !       ! from Sysin to MICFILE.;
DECsystem-10 SIMULA Language Handbook, part III          Page 112
7. UTILITIES SPECIFIC TO DECSYSTEM-10


     !       WHILE inline("Command:",Sysin).Strip =/= NOTEXT DO
     !       Outimage;
     !       Close
     !    END micfile creation;

     !    rc:= callmic(micfile,savfile);
     !    Outtext("Return code:");
     !    Outint(rc,5);
     !  Outimage;

     !END of program

     EXTERNAL PROCEDURES required:
     BOOLEAN PROCEDURE scratchfile;  PROCEDURE run;
     INTEGER PROCEDURE save; TEXT PROCEDURE tmpnam,conc,tmpout;


     IF micfile =/= NOTEXT THEN
     BEGIN   INTEGER returncode;   TEXT cmdfile;

         tmpout("MIC",conc("/",micfile));

         IF savfile =/= NOTEXT THEN
         BEGIN
             INSPECT
             NEW Outfile(conc(micfile,"/ACCESS:APPEND")) DO
             BEGIN   Open(Blanks(40));
                 Outtext(".REVIVE .RUN ");
                 Outtext(savfile);   Close
             END add sav file name;
             returncode:= save(savfile,TRUE);
             IF returncode = 0 THEN
             run("SYS:MIC",2) ELSE
             IF returncode < 0 THEN
             BEGIN   Outtext("? Save failed with filename:");
                 Outtext(savfile);   Outimage
             END ELSE
             scratchfile(savfile);
         END savfile =/= notext ELSE run("SYS:MIC",2);

         scratchfile(micfile);
         scratchfile(tmpnam("MIC"));
         scratchfile(cmdfile);
         stop:   callmic:= returncode;
     END of callmic;
DECsystem-10 SIMULA Language Handbook, part III          Page 113
7. UTILITIES SPECIFIC TO DECSYSTEM-10


**** TEXT PROCEDURE checkextension(t,defaultextension);
     VALUE defaultextension;   TEXT t,defaultextension;

     CHECKEXTENSION may be used to add a default extension to
     file specifications not containing a dot ('.').  I.e.
     ! T:- Copy("A");!   T:- checkextension(T,".SIM");
     ! will give T the value "A.SIM", while
     ! T:- Copy("A.");!   T:- checkextension(T,".SIM");
     ! will leave T unaltered.
     ! T:- Copy("LPT:");!   T:- checkextension(T,".SIM");
     ! will leave T unaltered.
     ! T:- Copy("LPT: A");!   T:- checkextension(T,".SIM");
     ! will give T the value "LPT: A.SIM".
     ;
     EXTERNAL PROCEDURES required:
     CHARACTER PROCEDURE findtrigger;
     TEXT PROCEDURE conc,rest;

     IF t =/= NOTEXT THEN
     BEGIN   t.Setpos(1);
             IF findtrigger(t,Copy(":")) NE ':' OR
             rest(t).Strip =/= NOTEXT THEN
             BEGIN   t.Setpos(1);
                 IF findtrigger(t,Copy(".")) NE '.' THEN
                 t:- conc(t,defaultextension) ELSE t.Setpos(1);
             END;
             checkextension:- t
     END of checkextension;


**** INTEGER PROCEDURE depbyte(val,w,firstbit,len);
     INTEGER val,w,firstbit,len;

     Returns the value of W with the modification:
     The byte starting at FIRSTBIT (0-35) of length LEN bits is
     replaced by VAL.  LEN>=0 AND LEN<=36 AND FIRSTBIT+LEN<=36
     must hold.  Note:  The last LEN bits of VAL will be used,
     the other bits will be ignored.


**** CLASS dirhnd

     DIRHND contains data structures which can be loaded with
     information from TOPS-10 directory files (UFD and SFD
     files).  The procedure LOADSELECTEDFILENAMES can be used to
     read this information, selecting certain file names
     according to a wild card pattern (see MATCH6, WILDSIX).
     LOADSELECTEDFILENAMES is an attribute of CLASS
     DIRECTORYPATH, which is declared inside DIRHND and contains
     information defining the directory file.  The directory
     information is placed in objects of class DIRECTORYBLOCK,
DECsystem-10 SIMULA Language Handbook, part III          Page 114
7. UTILITIES SPECIFIC TO DECSYSTEM-10


     which are reached via objects of FILENAMELIST class
     SIXBITFILENAMELIST.  DIRHND is only rudimentary at present
     and CANNOT BE USED on DECsystem-20 (TOPS-20).


**** PROCEDURE echo(fileref,mode);  REF(Infile)fileref;  INTEGER
     mode;

     Provided fileref refers to a TTY file, different values of
     mode have the following effects:
     mode=0 resets the mode to normal.
     mode=1 sets special editor mode.
     mode=2 suppresses echoing on the terminal completely.
     mode=4 causes all characters to echo exactly as typed.
     Combinations are possible where meaningful, i e 5=4+1.
     No effect on other files.


**** INTEGER PROCEDURE filcopy(source,dest);
     REF(Infile)source;  TEXT dest;

     Copies the SOURCE file to the (new) file specified by the
     text DEST, which is a normal DECsystem-10 (or -20) file
     specification acceptable to the SIMULA run time system.  A
     NEW Outfile(dest) is created, and the contents of source are
     copied to the new file buffer by buffer (using TOPS-10 I/O,
     thus the PA1050 compatibility must be used under TOPS-20).
     !!!  ONLY DISK FILES are handled !!!
     FILCOPY copies the file without changing the creation date
     as ordinary SIMULA code would do, and does it rather
     efficiently without using Image.  The disk space allocation
     is taken from the source file lookup data, minimizing
     fragmentation.  If a long file is copied, it may be useful
     to allocate more than 2 standard buffers for each file
     (/BUFFERS switch).

     FILCOPY returns -1 on success, 0 otherwise (or 2 if one of
     the files is not a disk file).
DECsystem-10 SIMULA Language Handbook, part III          Page 115
7. UTILITIES SPECIFIC TO DECSYSTEM-10


**** INTEGER PROCEDURE flokup(f);
     INTEGER f;

     F contains the address of a control block suitable for the
     FILOP. UUO (See Monitor Calls).  The .FOLEB field must
     contain a pointer to a lookup block (ordinary 4-word block
     or an extended lookup block).  FLOKUP looks up the file
     given by the lookup block and also determines the exact path
     of the file (placed in the PATH. block pointed to by the
     .FOPAT field).  On entry, the FILOP. block must contain i/o
     channel number in .FOFNC(F), SIXBIT device name in
     .FODEV(F), i/o mode in .FOIOS(F), addresses of PATH. and
     lookup blocks in .FOPAT(F), .FOLEB(F).  The lookup block
     must contain information (path, filename and extension in
     sixbit) for finding the file.  If the file can be found, the
     value of FLOKUP=F and the various blocks are updated,
     otherwise the value FLOKUP=0 is returned.
     WARNING:  FLOKUP should only be used in special cases when
     the ordinary SIMULA i/o procedures are inadequate.


**** TEXT PROCEDURE filspc(fileref,format);
     REF(FILE)fileref;  INTEGER format;

     Returns a string specifying a file:
     in TOPS-10:  dev:file.ext[path]<prot>
     in TOPS-20:  str:<directory>file.ext;Pnnnnnn
     FORMAT is an integer which specifies the fields to be
     included in the resulting string.  FORMAT is basically
     treated as a packed integer array, where most elements are 3
     bits wide.  Each 3-bit integer controls one field of the
     output string.  The value of a controlling integer can be:
     0:  Suppress the field.  1:  Always output the field.
     2:  Suppress the field if it is the system default.
     The following octal values would be used to always output
     the corresponding fields:
     8R 100000 000000 (2^33) Output DEVICE (File structure)
     8R 010000 000000 (2^30) Directory name in TOPS-20, ppn
     (+SFD) path in TOPS-10
     8R 001000 000000 (2^27) File name (value=2 illegal)
     8R 000100 000000 (2^24) File type (extension) (value=2
     illegal)
     8R 000010 000000 (2^21) File generation number (not
     implemented)
     8R 000001 000000 (2^18) Protection
     8R 000000 040000 (2^14, one bit) Temporary file (only in
     TOPS-20)
     The remaining field control bits used are:
     8R 000000 000001 (2^0) Punctuate All Fields, e g
     DEV:NAME.EXT[p,pn,sfd1,sfd2] The format is adapted from the
     control word for the JFNS JSYS in TOPS-20 (see the Monitor
DECsystem-10 SIMULA Language Handbook, part III          Page 116
7. UTILITIES SPECIFIC TO DECSYSTEM-10


     Calls manual for TOPS-20) to make it easy to modify when and
     if full TOPS-20 support will be included in the SIMULA
     system.  FORMAT=0 or omitted is equivalent to
     8R 221110 000001 -
             dev:name.ext[proj,prog,sfd1,...] (TOPS-10)
             dev:<directory>name.typ.gen;T    (TOPS-20)
     with dev:  omitted if it is DSK, <directory> omitted if it
     is the connected directory, [proj,...] omitted if it is the
     default path.
     Requires the external module FILEST (entry .FILST).


**** INTEGER PROCEDURE gettab(table,index);
     INTEGER table,index;
     Executes GETTAB ac, where ac is [index,,table].  See Monitor
     Calls Manual.


**** TEXT PROCEDURE idrx50(w);  INTEGER w;

     Converts bits 4-35 of W to a RADIX50 identifier text
     (Length=6).  Bits 0-3 are
     1) stored in idrx50.Main.Sub(1,1) directly,
     2) Converted to octal (after appending 2 zero bits to the
     right) in idrx50.Main.Sub(2,3), where the last char is
     blank.
     The following relation holds:
             idrx50.Main.Sub(5,6) == idrx50.
     Example:  Octal 123456701234 is converted to "?10 OQ5H%3",
     where ?  stands for Char(8r10//4) = Char(2) (=^B).


**** TEXT PROCEDURE idsixbit(id6a,id6b);
     INTEGER id6a,id6b;

     Converts the two words id6a,id6b to a 12-character text
     (ASCII).  The result is Strip of this identifier.  If only 6
     or fewer characters are relevant, use zero as second
     parameter.
DECsystem-10 SIMULA Language Handbook, part III          Page 117
7. UTILITIES SPECIFIC TO DECSYSTEM-10


**** INTEGER PROCEDURE intrea(x);  REAL x;

     Provides type conversion REAL to INTEGER.  The real x is
     interpreted as an integer quantity with the same bit
     pattern.  Use with care - highly machine dependent!


**** INTEGER PROCEDURE jobstatus(f);
     REF(Infile)f;

     Returns the job status for a TTY or PTY associated with the
     file object F.  See PTYCHECK for interpretation of the value
     returned.


**** INTEGER PROCEDURE loadbyte(bp,incr);
     INTEGER bp,incr;

     Load a byte via the standard byte pointer BP, modified INCR
     bytes.  If INCR < 0 or INCR > 1, the ADJBP instruction,
     which is not implemented on KA-10 or KI-10 processors, is
     used.  Example:  If t:-Copy("ABCDEFGH"),
     LOADBYTE(ABSADR(t),5) = Rank('F').
     LOADBYTE(8R222215 000001,0) gives the address of the
     prototype of the current "main" block, i.e. the prefixed
     block, class object, procedure instance or unreduced block
     which is innermost in the operating chain.  The byte pointer
     is POINT 18,1(15),18.
     **** WARNING:  To be used with caution.  Highly machine- and
     implementation dependent.  See STOREBYTE, STOREWORD.


**** INTEGER PROCEDURE loadword(adr);
     INTEGER adr;

     Returns the 36-bit word at address ADR, if valid, otherwise
     gives "Illegal memory reference" (possibly "Object NONE").
     **** WARNING:  To be used with caution.  Highly machine- and
     implementation dependent.  See STOREWORD.


**** INTEGER PROCEDURE match6(id1,id2,mask);
     INTEGER id1,id2,mask;

     ID1 (without wild card characters '?' or '*') is tested
     against ID2 with MASK showing wild card positions in ID2 if
     any.  The result is 1 for an exact match, -1 for a wildcard
     match, 0 for no match.  ID1 and ID2 are in SIXBIT code.  The
     wildcard character '?' matches any character.  '*' is
     equivalent to 6 or less '?' characters:  "*" => "??????",
     "AB*" => "AB????".  The wildcard MASK has octal 77 for each
DECsystem-10 SIMULA Language Handbook, part III          Page 118
7. UTILITIES SPECIFIC TO DECSYSTEM-10


     '?' in ID2, zeros in the other positions.  See WILDSIX.


**** BOOLEAN PROCEDURE numbered

     The BOOLEAN PROCEDURE numbered should always be called
     immediately after inimage.  It will return TRUE if the last
     input line was numbered.  The internal flag will be reset by
     numbered and may be changed by each inimage, even on other
     files.  For output of line-numbered files, see the
     information in the DECsystem-10 SIMULA Language Handbook
     part II about the file creation switch /NUMBERED.


**** TEXT PROCEDURE octal(t,n);
     TEXT t;  INTEGER n;

     Returns an octal representation (digits 0-7) of the bit
     pattern in N.  T is used as workspace.  If T.Length < 12,
     only the low-order part of N is converted (truncated to the
     left).  OCTAL.Length = Min(12,T.Length).  OCTAL.Main ==
     T.Main.  OCTAL.Pos points to the first non-zero digit.
     Example:  t:-Blanks(10);  OCTAL(t,-345)="7777777247";
     OCTAL(345)="0000000531", Pos=8, thus REST(OCTAL(...))="531".


     CONTROLLING SUBJOBS (PTY HANDLING)

     Sometimes it is useful to be able to control a subjob from a
     SIMULA program.  The subjob can do some tasks in parallel
     with the controlling job or perform some services which
     could not be handled by the controlling job without
     interrupting it, perhaps with loss of data and time.  A
     subjob is controlled by means of a PTY (pseudo-teletype),
     which is implemented by monitor software to act as
     controlling terminal for the subjob.  A PTY is handled like
     a terminal using buffered i/o.  The following procedures are
     coded to aid handling of PTY's in a SIMULA program:
     - PTYFIL defines an Outfile object to be used for sending
     commands to the subjob.  The output from the subjob goes to
     the Infile object which is a parameter to PTYFIL.
     - PTYINIMAGE is used to get the output from the subjob.  The
     ordinary Inimage procedure for Infiles cannot be used
     because it would loop when there is no input available, or
     when the job output does not end with a break character.
     - PTYCHECK can be used to wait until the subjob becomes
     interactive, i.e. has output available or can accept input.
     - JOBSTATUS can be used to check the status of the subjob
     without waiting.
     - INPUTWAIT can be used to wait for activity on PTY's as
     well as TTY's.
DECsystem-10 SIMULA Language Handbook, part III          Page 119
7. UTILITIES SPECIFIC TO DECSYSTEM-10


     - Actions to control a subjob:
     1) Creation of a NEW Infile("PTY:xxx") (specific PTY if
     desired).
     2) ptyout:-PTYFIL(ptyin), where ptyin is the Infile above.
     3) ptyin.Open(Blanks(Sysin.Length)) for example.
     ptyout.Open(Blanks(Sysout.Length)).
     4) Ordinary Outfile operations (Outchar, Outtext, Outimage,
     Breakoutimage) are used for sending commands to the subjob.
     Note that no password is required if you LOGIN on the same
     ppn as the main job.  Check if the job can accept commands
     (JOBSTATUS, PTYCHECK, INPUTWAIT) before sending any.
     5) Check for job output by PTYCHECK, JOBSTATUS, INPUTWAIT
     and use PTYINIMAGE to read the output.
     6) Before closing the two PTY files, log out the job,
     otherwise it will become detached when the channel is
     RELEASEd.  The ordinary SIMULA Close procedure has been
     modified to work with PTY.
     ****WARNING**** PTY handling has not been extensively
     checked.  Proper operation is not guaranteed!  See Monitor
     Calls for details of PTY handling.  Additional functions may
     be implemented by the XCALLI procedure, see below.


**** INTEGER PROCEDURE ptycheck(ptyin,timelimit);
     REF(Infile)ptyin;  REAL timelimit;

     Returns job status (according to JOBSTS UUO) if PTY can
     accept input or has output within the time limit, otherwise
     zero.
     Interpretation of returned value:
     JB.UJA  8R400000 000000 (negative) Job number is assigned.
     JB.ULI  8R200000 000000 Job is logged in.
     JB.UML  8R100000 000000 TTY is at monitor level.
     JB.UOA  8R040000 000000 TTY output is available.
     JB.UDI  8R020000 000000 TTY at user level in input wait,
                             or at monitor level and can
                             accept a command.
     JB.UJC  8R010000 000000 JACCT is set. In particular,
                             ^C^C will not work.
     JB.UJN  8R000000 777777 Job number or zero.
     If 0<timelimit<0.001, ptycheck does not wait. If timelimit
     <=0, it waits
     indefinitely.
DECsystem-10 SIMULA Language Handbook, part III          Page 120
7. UTILITIES SPECIFIC TO DECSYSTEM-10


**** REF(Outfile) PROCEDURE ptyfil(ptyinf);
     REF(Infile)ptyinf;

     Provided PTYINF is an Infile on device PTY, an Outfile will
     be opened on the same channel (the same PTY).  The result of
     PTYFIL is a reference to that Outfile object.


**** INTEGER PROCEDURE ptyinimage(ptyin);
     REF(Infile) ptyin;

     Performs Inimage for a PTY Infile.  Does not need a break
     character to stop input.  The result is the break character
     combination:  7 (^G, BELL), 10 (LF), 11 (VT), 12 (FF), 13
     (CR without following LF), 26 (Z), 27 (ESC).  CRLF is two
     characters = 128*13+10=1674.  Special codes:
     0 - No break character (null found),
     -1 for an empty buffer (no input available),
     -2 for no more space in Image, without having found break
     character
     -3 for other error (to be elaborated?).

     The file must be open and be associated with a pseudo-tty.
     NOTE!  Image must be an initial subtext of Image.Main, i.e.
       Image.Main.Sub(1,Image.Length) == Image.
     PTYINIMAGE sets Image=Image.Strip, except if
     Image.Strip==NOTEXT.
     In that case Image = " " and Image.Pos=2.


**** INTEGER PROCEDURE rename(fs1,fs2,force);
     NAME fs1,fs2,force;  BOOLEAN force;  TEXT or REF(FILE) fs1;
     TEXT fs2;

     FS1 is either a file specification text or a reference to a
     file object.  FS2 is a (partial) file specification.
     Missing fields are taken from FS1.  Information from FS2 is
     substituted in FS1 and a RENAME UUO is executed.  If
     FS2==NOTEXT, the file defined by FS1 is deleted.  If
     FORCE==TRUE, a RENAME changing only the protection is tried
     first, then a full RENAME.  The result is -1 if RENAME
     worked, error code if not.  Common error codes:
     ERFNF% 0        File not found (refers to first file)
     ERIPP% 1        Illegal path (ppn or full sfd path)
     ERPRT% 2        Protection failure
     ERAEF% 4        Already existing filename

     Special error codes:
     notdsk 1000     FS1 device is not disk
     reoper 1001     Could not reopen FS1
     fs2err 1002     Error in FS2
DECsystem-10 SIMULA Language Handbook, part III          Page 121
7. UTILITIES SPECIFIC TO DECSYSTEM-10


     deverr 1003     Cannot change device (FS2 dev not same as
     FS1)

     Other error codes are listed in the DECsystem-10 Monitor
     Calls manual.


**** INTEGER PROCEDURE rdx50(id,code);
     TEXT id;  INTEGER code;

     COMMENT
     Converts id to "RADIX50" code.  At most 6 characters
     allowed.  Only letters (treated as upper case), digits and "
     .$%" allowed.  CODE must be 0 or > 3 and <= 8R74.

     EXTERNAL procedures required:
     INTEGER PROCEDURE absadr, storebyte;
     INTEGER PROCEDURE bitfield;  ;

     TEXT t;  INTEGER i,j;  CHARACTER c;
     t:- IF id.Length > 6 THEN id.Sub(1,6) ELSE id;
     WHILE t.More DO
     BEGIN
         c:= t.Getchar; i:= i * 8R50;
         IF Letter(c) THEN
         BEGIN i:= i + Rank(c) - 8R66;
             IF c >= 'a' THEN i:= i - 8R40;
         END ELSE
         IF Digit (c) THEN i:= i + Rank(c) - 8R57 ELSE
         IF c = '.' THEN i:= i + 8R45 ELSE
         IF c = '$' THEN i:= i + 8R46 ELSE
         IF c = '%' THEN i:= i + 8R47 ELSE
         IF NOT c = ' ' THEN GOTO out;
     END;
     FOR j:= t.Length - 5 STEP 1 UNTIL 0 DO i:= i * 8R50;
     IF NOT code = 0 THEN
     BEGIN
         code:= bitfield(code,30,4);
         storebyte(code,8R400400000000 + absadr(i),0);
     END;
     rdx50:= i;
     out:
     END rdx50;
DECsystem-10 SIMULA Language Handbook, part III          Page 122
7. UTILITIES SPECIFIC TO DECSYSTEM-10


**** INTEGER PROCEDURE reaint(x);  REAL x;

     Provides type conversion INTEGER to REAL.  The integer x is
     interpreted as an real quantity with the same bit pattern.
     Use with care - highly machine dependent!


**** BOOLEAN PROCEDURE rescan;
     A SIMULA program is normally started by some monitor
     command.  RESCAN backs up the TTY input buffer, if possible,
     so that the invoking command can be reread.  If the command
     line can be reread, RESCAN returns TRUE, else FALSE.  The
     next input (of a line or a character) from the controlling
     TTY (normally SYSIN) will return the command line which
     started the SIMULA program, e g:
             RUN prog-<parameters>
     The monitor command scanner allows command lines which
     contain extra information not expected by the monitor
     itself.  The extra information should be preceded by a
     character which is not in the command syntax, like '-', '('.

     RESCAN must be called BEFORE the first input from the
     terminal.  If RESCAN is to be used, file specifications
     cannot be taken from the terminal.  Any error dialogue
     before RESCAN is called will render it useless.  Also, you
     cannot expect RESCAN to work if you start the program
     directly after loading by an EXECUTE or DEBUG command.  If
     you do not have the program in executable form, you should
     use LOAD, then START <some info>.  Programs using RESCAN
     should always provide an alternative way of getting the
     information.
     Example (from SIMED):
     EXTERNAL BOOLEAN PROCEDURE rescan;
     EXTERNAL TEXT PROCEDURE scanto,rest,inline;
     TEXT initcommand,t;
     IF rescan THEN
     BEGIN Inimage;
        t:-Sysin.Image.Strip;
        IF t=/=NOTEXT THEN t:-Copy(t);
        scanto(t,'-'); ! t.Pos after '-' or at end of command
     line;
        initcommand:- rest(t);
     END scanning command line;
      ...
     TEXT command;
     command:- IF initcommand =/= NOTEXT THEN initcommand
               ELSE inline("*",Sysin);
      ...
     The command R SIMED-X.SIM[100,101]
     will yield initcommand = "X.SIM[100,101]", and
     just R SIMED will yield initcommand == NOTEXT, causing a
DECsystem-10 SIMULA Language Handbook, part III          Page 123
7. UTILITIES SPECIFIC TO DECSYSTEM-10


     prompting "*" to be output to show that a command is
     expected.


**** SIMATR PROGRAM

     Displays ATR file information.  This improved version is
     written in SIMULA.  It displays the SIMULA skeleton of the
     separately compiled module together with unique entry names
     (also for other required external modules).  The external
     classes DIRHND and ATRSTR are required to load SIMATR, a
     well as a number of external (LIBSIM) procedures.


**** INTEGER PROCEDURE sixbit(t);
     TEXT t;

     Converts at most 6 characters from the ASCII text T to
     SIXBIT, i.e. the code used in the TOPS-10 monitor for names
     of devices, files, commands.  Each character in SIXBIT is 6
     bits, thus only 64 different characters can be represented,
     half as many as in ASCII.  Lowercase letters are treated as
     upper case, and control characters (Char(0) - Char(31))
     cannot be represented.  SIXBIT translates the first 6
     characters of T to sixbit code by subtracting 32 from each
     character value < 96 and 64 from the others.  Negative
     values are made zero (space in sixbit code).  The result is
     an integer, left justified, which could be used as a sixbit
     quantity e.g. with some XCALLI functions.  The inverse
     function is IDSIXBIT, q.v. See also OCTAL for a way of
     representing bit patterns as text strings.


**** INTEGER PROCEDURE sxrx50(w);  INTEGER w;

     Converts bits 4-35 of W to a RADIX50 identifier expressed in
     SIXBIT code (Length=6).  Example:  Octal 123456701234 is
     converted to SIXBIT "OQ5H%3".  Bits 0-3 are ignored.


****INTEGER PROCEDURE storebyte(b,bp,incr);
     INTEGER b,bp,incr;

     Using the byte pointer BP (careful if index and indirection
     fields are not zero) store the byte B (last bits according
     to byte size) by a DPB or IDPB instruction.  If INCR=0 use
     DPB, if =1 use IDPB, otherwise modify by ADJBP (only
     possible on KL-10/20 systems).  See LOADBYTE.
DECsystem-10 SIMULA Language Handbook, part III          Page 124
7. UTILITIES SPECIFIC TO DECSYSTEM-10


****INTEGER PROCEDURE storeword(w,adr);
     INTEGER w,adr;

     Stores the 36-bit word W at address (ADR) in core.  For
     convenience, the result of the function is the stored value.
     Note that indirect addressing is used, which means that the
     effective address is modified by any index register
     specified in bits 14-17 and indirection will be used if bit
     13 is 1.  This is dangerous since you cannot control the
     contents of ac's in general.  Use this procedure ONLY if you
     know EXACTLY what you are doing!  LOADWORD is the complement
     of STOREWORD.


**** TEXT PROCEDURE tmpin(nam,delete);
     VALUE nam;  TEXT nam;  BOOLEAN delete;
     Uses the TMPCOR UUO to read the core file NAM into a new
     text object.  If a core file is not found, a file with name
     "TMPNAM(NAM)" (see below) is tried instead (read in dump
     mode if found).
     If DELETE is TRUE, the file is deleted after reading.
     Returns NOTEXT if the file was not found, Blanks(1) if found
     but empty.
     In the latter case Pos=2 also, otherwise 1.  Information to
     be read by TMPIN may be created using TMPOUT (see below).


**** TEXT PROCEDURE tmpnam(nam);
     VALUE nam;  TEXT nam;

     TMPNAM takes one parameter NAM.  The parameter may be a text
     constant, variable or expression whose first three
     characters (or fewer than 3 if NAM.Length is less) are used
     when forming a temporary file name which is the value of
     TMPNAM.  The name has the form "jjjnam.TMP", where jjj is
     the current job number in decimal notation, and nam are the
     first three or fewer characters of the parameter.

     File names of this form are used for command files to
     standard CUSP's, such as SIMULA, PIP, LINK-10 and should
     also be useful for internal scratch files in a SIMULA
     program.  See the RUN procedure for examples.
DECsystem-10 SIMULA Language Handbook, part III          Page 125
7. UTILITIES SPECIFIC TO DECSYSTEM-10


**** BOOLEAN PROCEDURE tmpout(nam,txt);
     NAME nam;  TEXT nam,txt;
     Uses the TMPCOR UUO to write the core file NAM from TXT.  If
     TMPCOR fails, a real file named "TMPNAM(NAM)" (see TMPNAM
     procedure) is opened instead, and TXT is written in dump
     mode.
     Returns FALSE if the file could not be written, TRUE on
     success.  No carriage return-line feed will be supplied -
     must be in TXT if needed.  The text should start and end on
     a word boundary.


**** INTEGER PROCEDURE trmop(funcod, iox, val);
     INTEGER funcod, val;  REF (Outfile) iox;

     TRMOP allows the SIMULA program to test and change the
     values of certain status items associated with a terminal
     connected to the SIMULA program via a file object.  The
     program can thus achieve the equivalents of the monitor
     commands .TTY NO ECHO, .TTY LC etc.

     FUNCOD is the four-digit octal code for the function to be
     performed.

     A first digit = 0 signifies a special function (usually a
     generalization of the TTCALL UUO for the job-controlling
     terminal).

     If the first digit is 1, a read function is performed, i. e.
     the current value of the field is returned as function
     value.

     If the first digit is 2, the corresponding value is set to
     the value given by VAL, and the old value is returned as
     function value.

     The effect of other values of the first digit is
     installation dependent.

     If the requested function cannot be performed, the value of
     the TRMOP function is -1.

     IOX is an outfile referring to the TTY involved.  IOX==NONE
     refers to the terminal controlling the job.

     VAL is the new value for the status item.  Redundant except
     for set function (FUNCOD=8R2xxx).

     TRMOP returns the old value of the status item when
     relevant.
DECsystem-10 SIMULA Language Handbook, part III          Page 126
7. UTILITIES SPECIFIC TO DECSYSTEM-10


     Special case:  for FUNCOD = 1 or 2, a skip return is mapped
     as the function value 1, non-skip return as 0.

     Example I:  "TRMOP(8R1003,sysout,0)" returns 1 if the
     previous setting was "TTY NO LC", returns 0 if the previous
     setting was "TTY LC".  (TTY NO LC means that the monitor
     converts all lower case letters to upper case in
     transmissions from the conversational terminal.)

     Example II:  "TRMOP(8R2003,sysout,1)" is equivalent to the
     monitor command "TTY NO LC".

     All the status items which can be interrogated or set by
     TRMOP are listed in the DECsystem-10 Software Notebooks,
     "DECsystem-10 monitor calls", (DEC-10-OMCMA-B-D), Section
     11.2.4.  Here is an excerpt of the most useful items:

     FUNCOD  value
     8R1003  1 = NO LC (lower case)
     8R1005  0 = NO TAB (tabs converted to multiple spaces)
     8R1006  0 = NO FORM
     8R1007  1 = NO ECHO (printable characters not echoed)
     8R1010  1 = NO CRLF (monitor inserts no extra CR-LFs)
     8R1011  Horizontal position of carriage
     8R1012  Carriage width (TTY WIDTH) = Create <CR><LF> at
     given
             position in line
     8R1013  1 = NO GAG (accepts external messages)
     8R1017  TTY FILL (filler class index, governs number of fill
             chars after FF and CR)
     8R1024  Number of lines output on this page
     8R1026  0 = ASCII codes 175 and 176 converted to altmode
     8R1035  Create <CR><LF> at first space after given position
             in line
DECsystem-10 SIMULA Language Handbook, part III          Page 127
7. UTILITIES SPECIFIC TO DECSYSTEM-10


**** INTEGER PROCEDURE ttyline(ttyn); TEXT ttyn;
     ! Required external procedures: ;
     EXTERNAL INTEGER PROCEDURE xcalli, sixbit;
     EXTERNAL TEXT PROCEDURE scanto, idsixbit;
     BEGIN
     ! Accepts tty name or number (octal format).
     ! Returns node*218+line if network is in effect,
     ! just line no if not, or zero on error.
     ;
     CHARACTER c;
     TEXT t;
     INTEGER sixname, n;
     t:- ttyn;
     IF t =/= NOTEXT THEN
     BEGIN c:= t.Getchar;
         IF Letter(c) THEN
         BEGIN
             sixname:= sixbit(t);
             sixname:= xcalli(8R64,sixname,TRUE,0); ! DEVNAM;
             t:- idsixbit(sixname,0);
             IF t.Sub(1,3) NE "TTY" THEN GOTO error;
             ttyn:- t.Strip;
         END letter ELSE
         IF Digit(c) THEN
         BEGIN ttyn:- Copy("TTY   "); ttyn.Setpos(4);
             GOTO pc;
             WHILE t.More AND ttyn.More DO
             BEGIN 
                 c:= t.Getchar;
             pc: ttyn.Putchar(c);
             END;
         END digit;
         ttyn.Setpos(1);
         ttyline:= xcalli(8R165,sixbit(ttyn),TRUE,0); ! GTNTN.;
     END;
     error:
     ;
     END;
DECsystem-10 SIMULA Language Handbook, part III          Page 128
7. UTILITIES SPECIFIC TO DECSYSTEM-10


**** TEXT PROCEDURE ttynumber(node,lineno);
     ! Required external procedures: ;
     EXTERNAL INTEGER PROCEDURE xcalli;
     EXTERNAL TEXT PROCEDURE idsixbit;
     INTEGER node, lineno;
     BEGIN
     ! Returns TTY number as octal ASCII text.
     ! Also returns full TTY device name as ttynumber.Main
     ! Example: TTY75: ttynumber = "75".
     !  ttynumber.Main = "TTY75:". Thus ttynumber.Main can be
     used directly
     !  as file specification for the TTY.
     ;
         INTEGER sixname;
         sixname:= xcalli(8R166,node*8R1000000+lineno,TRUE,0); !
     GTXTN.;
         IF sixname NE 0 THEN
         BEGIN TEXT t; t:- idsixbit(sixname,0);
             t:- t.Main.Sub(1,t.Length+1);
             t.Setpos(t.Length); t.Putchar(':');
             ttynumber:- t.Sub(4,t.Length-4);
         END;
     END;


FILED - FOR INPUTTING AND OUTPUTTING DEC-10/20 TEXT FILES:

     By Jacob Palme, Swedish National Defense Research Institute,
     S-104 50 Stockholm 80, Sweden.

     This program contains a class FILED (which can be separately
     compiled) to input and output DEC-10/20 ASCII-7-formatted
     text files in SIMULA.  The program can handle both
     unnumbered and line numbered text files.  For numbered
     files, the program will ensure that the output file has the
     line number format required by other DEC-10/20 text handling
     programs like SOS.  Lines without line numbers will be
     numbered.

     The good facilities for text handling make SIMULA a useful
     language for text handling programs like editors,
     programming language translators, compilers, pre-compilers
     etc.

     However, reading and writing text files on the DEC-10,
     especially line numbered files, is rather tricky in SIMULA.
     By using this program, you avoid those problems.

     The program can be found in a file with the name FILED.SIM
     on the SIMULA distribution tape.  At the QZ computing
     center, you may find the file FILED.SIM on DSKE:[13,134].
DECsystem-10 SIMULA Language Handbook, part III          Page 129
7. UTILITIES SPECIFIC TO DECSYSTEM-10


**** INTEGER PROCEDURE xcalli(n,arg,errnoskip,errvalue);
     INTEGER n,arg,errvalue;  BOOLEAN errnoskip;

     Executes CALLI AC1,N - where AC1 is loaded from ARG.
     ERRVALUE is returned if the CALLI does not skip, and
     ERRNOSKIP is TRUE.  See the Monitor Calls manual for CALLI
     UUO functions.  In TOPS-10, most of the monitor interface is
     handled by CALLI.  Examples:  XCALLI(8R30,0,FALSE,0)=job
     number, XCALLI(8R24,0,FALSE,0)=ppn (proj*2^18+prog),
     XCALLI(8R31,10,FALSE,0) will cause job to SLEEP 10 seconds,
     XCALLI(8R41,m*2^18+n,TRUE,0) will perform GETTAB(m,n) and
     return value of item or zero on failure.
     For more esoteric functions, you may have to provide an
     argument list pointed to by ABSADR(first word of list).
     Example:
     INTEGER rundev,runfile,runext,run3,runppn,runarg;
     rundev:=SIXBIT("SYS");  runfil:=SIXBIT("SIMULA");
     XCALLI(8R35,ABSADR(rundev),TRUE,0);  EXIT(0);
     Will start SIMULA in command mode or exit to monitor on
     failure.

     XCALLI should be used with great caution.  It is provided as
     a convenience where safer methods of achieving the desired
     results are too cumbersome or impossible.  By using XCALLI,
     you may not need to write a MACRO-10 procedure for a very
     small task, and experimenting is easier.  Be very careful
     not to cause any garbage collection between computation of
     an absolute address and its use!


**** INTEGER PROCEDURE wildsix(id,mask,k);
     NAME mask;  INTEGER mask, k;  TEXT id;

     Convert at most K (K <= 6) characters from ID to SIXBIT,
     taking special notice of "wild cards" as follows:  If a '?'
     is found, the corresponding position in MASK (byte size 6)
     will be made = 8R77.  If an asterisk ('*') is found, the
     rest of the characters up to number K (1<=K<=6) will be
     treated as '?'.  The result is the SIXBIT code of ID
     (initial K characters).  See PROCEDURE SIXBIT.
     Example:  ID="AB??", K=6 will give wildsix=8R414237370000,
     MASK=8R000077770000.
DECsystem-10 SIMULA Language Handbook, part III          Page 130
APPENDIX A - REALTIME - A SCHEDULER FOR TERMINAL PROCESSES


     APPENDIX A - REALTIME - A SCHEDULER FOR TERMINAL PROCESSES


     (The programs described in this appendix do not work on a
     DECsystem-20 at the time when this is written, April 1977.)





     CONTENTS


               A.1   REALTIME - A SCHEDULER FOR TERMINAL
                     PROCESSES
               A.2   PROCEDURES WAITFORINPUT, INPUTCHECK AND
                     HOLD(0).
               A.3   PROCEDURES CLOCKTIME, SYNCHRONIZE AND
                     DESYNCHRONIZE.
               A.4   STRUCTURE OF THE CLASS REALTIME
               A.5   APPLICATION EXAMPLES.

                    A.5.1.1 SIMULTANEOUS, UNINTERFERED DIALOGUE
                            BETWEEN THE COMPUTER AND SEVERAL REAL
                            TERMINALS
                    A.5.1.2 A COMPLETE PROGRAM USING THE CLASS
                            REALTIME.

                    A.5.2   DATA BASE SYSTEM, SEVERAL TERMINALS
                    A.5.3   LIMITED RESPONSE TIME FOR THE
                            TERMINAL OPERATOR.
                    A.5.4   A CONVERSATIONAL TIME-SHARING SYSTEM.
                    A.5.5   COORDINATED CONTROL OF SIMULTANEOUS
                            REAL PROCESSES.
                    A.5.6   SIMULTANEOUS DIALOGUE AND EXECUTION.
DECsystem-10 SIMULA Language Handbook, part III          Page 131
APPENDIX A - REALTIME - A SCHEDULER FOR TERMINAL PROCESSES


     This documentation is based on FOA P Report C 8394 (June
     1974):  "Making SIMULA into a Programming Language for Real
     Time" by Jacob Palme.  (Published in Management Informatics,
     Vol. 4, No. 4, August 1975, pp. 129-138.)


     The simplest kind of real time application is the execution
     of a conversational program running under a time-sharing
     system with one external user talking to the program through
     a terminal such as a display unit or a typewriter terminal.

     This simple interaction can already be easily programmed in
     SIMULA.  The time-sharing operating system will handle all
     the real time problems for the SIMULA program.

     But as soon as we want more than one real process to
     communicate simultaneously with the SIMULA program, more
     advanced real time capabilities are required.

     Examples:

      - We may want to write a simulation program which
     communicates with real components, e.g. human participants.

      - We want to let several users from separate terminals
     simultaneously access a data base, both fetching and storing
     information in it.  One master program has to coordinate the
     data base accesses so that two users do not simultaneously
     try to update the same record.  We might want to write this
     program in SIMULA.
DECsystem-10 SIMULA Language Handbook, part III          Page 132
APPENDIX A - REALTIME - A SCHEDULER FOR TERMINAL PROCESSES


A.1.3 Procedures WAITFORINPUT, INPUTCHECK and HOLD(0).

     The execution of a SIMULA process is only interrupted where
     explicit statements like "HOLD" or "PASSIVATE" cause control
     to transfer from the process to the scheduler.  A common
     error when programming real time programs is that one
     parallel process uses partly updated data, produced by
     another parallel process.  For small in-core updates, a
     programmer in SIMULA can avoid this error by only putting
     statements like "HOLD" and "PASSIVATE" at places in the
     source program where data updates are complete.

     For more complex updates, a special process can be written
     to access the critical data, and other processes requesting
     updates can be queued to the special process.  When a SIMULA
     process executes a statement like "HOLD" or "PASSIVATE",
     then control goes to the SIMULA scheduler, which then
     transfers control to another process.

     "HOLD(A)" stops execution of the current process but asks
     the SIMULA scheduler to restart it after A time units.  If A
     is zero, then the current process is stopped and placed at
     the end of a queue of currently active processes.  If a
     number of processes successively make "HOLD(0.0)" they will
     thus get access to the CPU in a round robin fashion.

     A SIMULA programmer can thus ensure fast response to
     external interrupts by not doing too much computations
     between successive "HOLDS".

     "PASSIVATE" stops the current process indefinitely, it must
     be activated again from some other process.

     Processes waiting for external interrupts are put into a
     special queue with the procedure call "WAITFORINPUT".  The
     "SIMULATION CLASS REALTIME" contains a special version of
     "HOLD" and an alternative version of "PASSIVATE" called
     "TERMINAL_PASSIVATE" and these procedures first scan this
     special queue to see if data has arrived from the input
     device associated with the terminal processes.

     If a process is found for which data has arrived on the
     associated input device, then the SIMULA scheduler activates
     this process immediately.

     The event created by the first external interrupt found is
     thus placed in front of other currently active processes in
     the sequencing set.  This, however, is not done at the time
     of the interrupt, the placing is done at the time of the
     next activation of the scheduler after the interrupt.
DECsystem-10 SIMULA Language Handbook, part III          Page 133
APPENDIX A - REALTIME - A SCHEDULER FOR TERMINAL PROCESSES


     Inside a terminalprocess, a call "WAITFORINPUT" will thus
     tell the system to make this process passive, but to
     reactivate it as soon as new data has arrived on the input
     device associated with the process.

     A new BOOLEAN standard procedure INPUTCHECK is also
     introduced.  INPUTCHECK is TRUE if and only if data is
     available (i.e.  has arrived from the terminal device) for
     reading with INIMAGE.



A.3 Procedures CLOCKTIME, SYNCHRONIZE and DESYNCHRONIZE.

     For real time applications, we may also want to synchronize
     simulated time with real time.  For this there are three new
     standard procedures:

     REAL PROCEDURE clocktime;  COMMENT gives time in seconds
     since the beginning of the current day;

     PROCEDURE synchronize(timeunit);  REAL timeunit;  COMMENT
     this procedure starts synchronization of real and simulated
     time;

     PROCEDURE desynchronize;  COMMENT and this stops
     synchronization;

     Of course perfect synchronization of real and simulated time
     is not possible since the speed of the computer itself is
     not infinite.  The package tries to synchronize, and never
     allows simulated time to become more than a fraction of a
     second greater than real time.

     Synchronization consumes some additional cpu time.

     If the scheduler finds that the next process to be scheduled
     has a too large simulated time, then the SIMULA scheduler
     lets the SIMULA program go to sleep for the necessary time
     interval.  Any interrupts caused by input will however start
     the SIMULA program again.

     The parameter "timeunit" to the procedure "synchronize" is
     there since the time unit may not be the same in the
     simulation as in the real world.  "timeunit" is the size of
     the simulation time unit in seconds.  Thus, if simulated
     time is measured in seconds, "timeunit" should be 1.0.  If
     simulated time is measured in hours, "timeunit" should be
     60*60.
DECsystem-10 SIMULA Language Handbook, part III          Page 134
APPENDIX A - REALTIME - A SCHEDULER FOR TERMINAL PROCESSES


A.4 Structure of the class REALTIME

     OPTIONS(/E);
     EXTERNAL BOOLEAN PROCEDURE inputcheck;
     EXTERNAL PROCEDURE sleep, abort;
     EXTERNAL INTEGER PROCEDURE inputwait;
     EXTERNAL REAL PROCEDURE clocktime;
     simulation CLASS realtime;
     NOT HIDDEN PROTECTED synchronize, desynchronize,
     terminal_passivate,
     hold, terminalprocess;
     NOT HIDDEN process, current, time, passivate, wait,
     main, linkage, link, head;
     BEGIN

       PROCEDURE synchronize(timeunit); REAL timeunit;
       COMMENT this procedure starts synchronization of real and
       simulated time;
       BEGIN ... END;

       PROCEDURE desynchronize;
       COMMENT This procedure ends synchronization of real and
       simulated time;
       BEGIN ... END;

       PROCEDURE terminal_passivate;
       COMMENT special version of passivate for a
       terminalprocess;
       BEGIN ... END;

       PROCEDURE wait(q); REF (head) q;
       COMMENT special version of wait for a terminalprocess;
       BEGIN ... END;

       PROCEDURE hold(delaytime); REAL delaytime;
       COMMENT special version of hold for terminalprocesses.
       hold(0.0) gives round robin process scheduling;
       BEGIN ... END;

       process CLASS terminalprocess(fromterminal);
       REF (infile) fromterminal;
       NOT HIDDEN PROTECTED fromterminal, waitforinput;
       NOT HIDDEN evtime, nextev, into;
       BEGIN

         PROCEDURE waitforinput;
         COMMENT this process waits until inimage is
         possible to make for some file in the input_array;
         BEGIN ... END;

       END of terminalprocess;
DECsystem-10 SIMULA Language Handbook, part III          Page 135
APPENDIX A - REALTIME - A SCHEDULER FOR TERMINAL PROCESSES


     END of class realtime;




A.5 Application examples.

     In this section you can see how the new concepts can be
     used.  Some examples will be given of real time programs
     written in SIMULA using the new concepts.

     The programs are not always complete.  Three dots indicate
     places where something has been left out.




A.5.1.1 Simultaneous, uninterfered dialogue between
     the computer and several real terminals.

     One master terminal reads file specifications for the other
     terminals and starts up one copy of the SIMULA CLASS
     "terminal" for each of the other terminals.  Each of these
     "terminalprocesses" will open the connection to its real
     terminal, and then go into a loop of (a) waiting for input
     and (b) producing answers.

     Each of these terminal loops will go on independently of the
     other, and the SIMULA scheduler will distribute control
     between the "terminalprocesses".

     terminalprocess CLASS terminal(toterminal);
     REF (outfile) toterminal;
     BEGIN
       INSPECT fromterminal DO
       INSPECT toterminal DO
       BEGIN
          PROCEDURE open_terminal_connections; ...
          PROCEDURE read_the_input_and_produce_an_answer; ...

          WHILE TRUE DO
          BEGIN
            waitforinput;
            read_the_input_and_produce_an_answer;
          END;
       END;
     END;
DECsystem-10 SIMULA Language Handbook, part III          Page 136
APPENDIX A - REALTIME - A SCHEDULER FOR TERMINAL PROCESSES


     ACTIVATE NEW terminal(sysin,sysout);
     ACTIVATE NEW terminal(NEW infile("TTY2:"),
                           NEW outfile("TTY2:"));
     ACTIVATE NEW terminal.....
     ....
     passivate;


A.5.1.2 A complete program using the CLASS REALTIME.

     Here follows a complete, small program using the CLASS
     REALTIME.
     At each terminal, the program returns the input
     received at that terminal. If the input at a terminal
     is a legal TTY device specification, that terminal
     is connected to the program.
     BEGIN
       EXTERNAL BOOLEAN PROCEDURE inputcheck;
       EXTERNAL PROCEDURE sleep, abort;
       EXTERNAL INTEGER PROCEDURE inputwait;
       EXTERNAL REAL PROCEDURE clocktime;
       EXTERNAL CLASS realtime;
       EXTERNAL REF (infile) PROCEDURE findinfile;
       EXTERNAL REF (outfile) PROCEDURE findoutfile;
DECsystem-10 SIMULA Language Handbook, part III          Page 137
APPENDIX A - REALTIME - A SCHEDULER FOR TERMINAL PROCESSES


       realtime BEGIN

         terminalprocess CLASS terminal(toterminal);
         REF (outfile) toterminal;
         BEGIN
           TEXT stripimage;
           INSPECT fromterminal DO INSPECT toterminal DO
           WHILE fromterminal.image.sub(1,2) NE "/*" DO
           BEGIN
             waitforinput; inimage;
             stripimage:- fromterminal.image.strip;
             IF stripimage =/= NOTEXT THEN
             BEGIN
               IF stripimage.sub(stripimage.length,1)
               = ":" THEN
               BEGIN COMMENT Connect another terminal;
                 IF connect(stripimage) THEN
                 outtext("NEW LINE OPEN. ") ELSE
                 outtext("NOT ABLE TO OPEN THAT LINE. ");
               END;
             END;
             outtext("I received: '");
             outtext(stripimage); outtext("'");
             outimage;
           END;
           toterminal.close; fromterminal.close;
         END;


         BOOLEAN PROCEDURE connect(filespec);
         VALUE filespec; TEXT filespec;
         INSPECT findinfile(filespec) DO
         BEGIN
           open(blanks(80));
           INSPECT findoutfile(filespec) DO
           BEGIN
             open(blanks(80));
             connect:= TRUE;
             outtext(
             "THIS TERMINAL IS NOW CONNECTED!");
             outimage;
             ACTIVATE NEW terminal
             (THIS infile, THIS outfile);
           END
           OTHERWISE close;
         END;
DECsystem-10 SIMULA Language Handbook, part III          Page 138
APPENDIX A - REALTIME - A SCHEDULER FOR TERMINAL PROCESSES


         ACTIVATE NEW terminal(sysin, sysout);
         passivate;
       END of realtime prefixed block;
     END of the whole program;


A.5.2 Data base system, several terminals
     use the same data base.

     This is a very simple example of a data base system with
     several conversational terminals which independently put
     requests (questions or updates) to a data base.  The actual
     data base accesses must be done for only one request at a
     time to avoid errors when one terminal tries to read what
     another terminal is updating.

     The SIMULA program contains one process for each terminal
     and one process for the data base.

     The terminal processes wait for input from their respective
     terminals.  When a data base request has been received, the
     terminal process is put into a queue of data base requests.

     The data base process takes one terminal process at a time
     from this queue and processes the data base request.
     Thereafter, the data base process ACTIVATEs the terminal
     process again.  When ACTIVATEd, this terminal process writes
     the answer to its terminal and waits for new requests from
     it.
DECsystem-10 SIMULA Language Handbook, part III          Page 139
APPENDIX A - REALTIME - A SCHEDULER FOR TERMINAL PROCESSES


     realtime BEGIN
     REF (head) request_queue;
     REF (data_base) the_data_base;

     terminalprocess CLASS terminal(toterminal);
     REF (outfile) toterminal;
     BEGIN
        INSPECT fromterminal DO
        INSPECT toterminal DO
        BEGIN
           PROCEDURE open_terminal_line; ...
           PROCEDURE read_and_prepare_data_base_request; ...
           PROCEDURE write_the_answer_to_the_request; ...

           WHILE TRUE DO
           BEGIN
              waitforinput;
              read_and_prepare_data_base_request;
              ACTIVATE the_data_base DELAY 0;
              wait(request_queue);
              write_the_answer_to_the_request;
           END;
        END;
     END;

     process CLASS data_base;
     BEGIN
        INSPECT NEW
        directfile(data_base_file_specifications) DO
        BEGIN
           PROCEDURE open_data_base_file; ...
           PROCEDURE put_the_request_to_the_data_base; ...

           open_data_base_file;
           WHILE TRUE DO
           INSPECT request_queue.first WHEN terminal DO
           BEGIN
              out; COMMENT to remove the terminal from the
              request queue;
              put_the_request_to_the_data_base;
              ACTIVATE THIS terminal;
           END OTHERWISE passivate;
        END;
     END;
DECsystem-10 SIMULA Language Handbook, part III          Page 140
APPENDIX A - REALTIME - A SCHEDULER FOR TERMINAL PROCESSES


A.5.3 Limited response time for the terminal operator.

     This is a very simple example of a program which is
     coordinated with the time in the real world.  A question is
     given to a terminal operator and the program waits for an
     answer.  The program should take different action depending
     on whether the answer is received within 60 seconds or not.

     To do this, the new standard procedure SYNCHRONIZE is used
     to synchronize real time with the simulated time in SIMULA.

     terminalprocess CLASS terminal(toterminal);
     REF (outfile) toterminal;
     BEGIN
        INSPECT fromterminal DO
        INSPECT toterminal DO
        BEGIN
           REAL questiontime;
           PROCEDURE write_question_to_the_terminal; ...
           PROCEDURE process_fast_answer; ...
           PROCEDURE process_slow_answer; ...

           synchronize(1.0);
           write_question_to_the_terminal;
           questiontime:= time;
           waitforinput;
           IF time - questiontime < 60.0 THEN
           process_fast_answer ELSE
           process_slow_answer;
        END;
     END;




A.5.4 A conversational time-sharing system.

     The conversational time-sharing system in this example could
     be an interpreter for a language like APL or FOCAL or AID.

     Highest priority is given to those input commands which are
     to be performed directly.  Lower priority is given to input
     commands requesting the execution of a stored program.  When
     several stored programs are in execution at the same time,
     CPU power is distributed between them in a round robin
     fashion letting each program perform one statement in the
     stored program before continuing to the next program.
DECsystem-10 SIMULA Language Handbook, part III          Page 141
APPENDIX A - REALTIME - A SCHEDULER FOR TERMINAL PROCESSES


     terminalprocess CLASS terminal(toterminal);
     REF (outfile) toterminal;
     BEGIN
        INSPECT fromterminal DO
        INSPECT toterminal DO
        BEGIN
           PROCEDURE open_terminal_connections; ...
           PROCEDURE read_the_input_and_produce_an_answer;
           BEGIN
              BOOLEAN more_statements, execute_command;
              PROCEDURE read_and_interpret_an_input_line; ...
              PROCEDURE
              execute_the_next_stored_program_statement; ...
              PROCEDURE perform_the_command_from_the_input_line;
              ...
              read_and_interpret_an_input_line;
              IF NOT execute_command THEN
              perform_the_command_from_the_input_line ELSE
              WHILE more_statements DO
              BEGIN
                 HOLD(0); COMMENT to transfer control to another
                 process;
                 execute_the_next_stored_program_statement;
              END;
           END;

           WHILE TRUE DO
           BEGIN
              waitforinput;
              read_the_input_and_produce_an_answer;
           END;
        END;
     END;
DECsystem-10 SIMULA Language Handbook, part III          Page 142
APPENDIX A - REALTIME - A SCHEDULER FOR TERMINAL PROCESSES


A.5.5 Coordinated control of simultaneous real processes.

     When a real time computer program communicates with several
     simultaneous processes in the real world, the computer
     program may want to control itself or the real-world
     processes depending on the results in the various processes.

     Example 1:  A simulation program may want to continue the
     simulation when all the terminals have replied to certain
     questions.

     Example 2:  A process control program may monitor several
     real-world processes, and initiate other real-world actions
     when previous processes are ready.

     This is similar to PERT-networks in planning, where certain
     actions must wait for other actions to finish.

     To illustrate this, a simple example assumes a robot with
     three arms.  A process "put nail in board" is initiated.
     This process initiates three simultaneous processes, the
     first arm gets a hammer, the second arm gets a nail, and the
     third arm gets a board.  When all these three processes are
     finished, the hammer is used to push the nail into the
     board.

     In other languages, special constructs like "fork" and
     "join" are used to create parallel processes and then
     continue when all the processes are ready.  But the same
     thing is very simple to program in SIMULA, and in SIMULA we
     do not have to wait until a process is completely finished,
     we can also easily start a later process when still running
     processes have reached certain states.
DECsystem-10 SIMULA Language Handbook, part III          Page 143
APPENDIX A - REALTIME - A SCHEDULER FOR TERMINAL PROCESSES


     terminalprocess CLASS arm(toterminal);
     REF (outfile) toterminal;
     BEGIN
        INSPECT fromterminal DO
        INSPECT toterminal DO
        BEGIN
           TEXT order; BOOLEAN ready; REF (process) master;
           PROCEDURE perform_order; ...
           WHILE TRUE DO
           BEGIN
              terminal_passivate;
              ready:= FALSE; perform_order; ready:= TRUE;
              ACTIVATE master DELAY 0;
           END;
        END;
     END;

     process CLASS put_nail_in_board(arm1, arm2, arm3);
     REF (arm) arm1, arm2, arm3;
     BEGIN
        arm1.order:- copy("find hammer"); arm1.master:- current;
        arm2.order:- copy("find nail"); arm2.master:- current;
        arm3.order:- copy("find board"); arm3.master:- current;
        ACTIVATE arm1 DELAY 0;
        ACTIVATE arm2 DELAY 0;
        ACTIVATE arm3 DELAY 0;
        terminal_passivate;
        WHILE NOT (arm1.ready AND arm2.ready AND arm3.ready)
        DO terminal_passivate;
        arm1.order:- copy("swing hammer");
        ACTIVATE arm1 DELAY 0;
         ...
     END;


A.5.6 Simultaneous dialogue and execution.

     On many occasions, you may want a program to execute and
     talk to the user at the same time.  You may for example want
     to allow the user to ask the computer how far the execution
     has reached.  This is especially useful for time-consuming
     executions, where the user may get impatient and may want to
     know if the delay is caused by machine error, erroneous data
     to the program, by a heavy load on the machine or just by a
     time-consuming execution in general.

     One can then write a program with two processes, one process
     for talking to the user and another process for the
     time-consuming execution.
DECsystem-10 SIMULA Language Handbook, part III          Page 144
APPENDIX A - REALTIME - A SCHEDULER FOR TERMINAL PROCESSES


     terminalprocess CLASS userdialogue(toterminal);
     REF (outfile) toterminal;
     BEGIN
        INSPECT fromterminal DO
        INSPECT toterminal DO
        BEGIN
           ACTIVATE NEW cpuactivity DELAY 0;
           WHILE TRUE DO
           BEGIN
              outline("CPU activity has begun. If you want to");
              outline("know what is happening, then type");
              outline("""?"" on your terminal");
              waitforinput; inimage;
              tell_the_user_what_is_happening;
           END;
        END;
     END;
DECsystem-10 SIMULA Language Handbook, part III          Page 145
APPENDIX B - CONTROLLED ERROR HANDLING


     APPENDIX B - CONTROLLED ERROR HANDLING

     By Stefan Arnborg August 1975, Modified October 1975

     CONTENTS

          B.1 PROBLEM

          B.2 SOLUTIONS

          B.3 CHOICE OF SOLUTION FOR SIMULA

          B.4 PROPOSAL

          B.5 DISCUSSION


     The procedures MASKERROR, SENSEERROR, JUMPERROR and
     RESETERROR described below have not yet been implemented,
     and no promise is made about if or when to do so.


B.1  Problem.

     Dependable software must be prepared to detect and diagnose
     errors in input data.  For complex problems error handling
     will take a significant part of the programming effort.
     Programmed error handling is a means to achieve error
     handling without having to reprogram in SIMULA checks
     actually made by the programming system and the hardware.
     The absence of this facility has been used as one argument
     for using PL/1 rather than SIMULA at FOA.


B.2  Solutions.

     Programmed error handling in other programming systems and
     environments usually falls in one of three classes:

     A  Implicit action.

     In CDC Algol an error may cause a jump to a preset label.
     In the Knuth proposal for I/O in Algol 60, errors may cause
     predefined procedures to be called.  In PL/1 an error may
     cause a previously set ON-unit to be activated.
DECsystem-10 SIMULA Language Handbook, part III          Page 146
APPENDIX B - CONTROLLED ERROR HANDLING


     B  Error returns.

     The READ/WRITE statements of many FORTRAN implementations
     permit error and end-of-file exit labels to be passed as
     parameters.  Many general-purpose algorithms in ACM
     collected algorithms have parameters returning error codes
     or error exit label parameters.

     C  Raising flags.

     In the CODASYL DBMS proposal, an error condition raises
     flags that can be inspected by the program.


B.3  Choice of solution for SIMULA.

     The following requirements on a solution are rather obvious:

     i)   Existing programs should not be affected unless the
          user wants to take advantage of the facility.

     ii)  It must be easily implemented on existing systems.

     iii) It must be well defined and easy to use.

     iv)  It must be compatible with the overall language
          philosophy.

     v)   In particular, it must be as implementation independent
          as possible.

     Method A seems to satisfy i) and v) but contradicts the
     other requirements.  In particular, it requires much
     programming effort (at least in the IBM 360 and DEC 10
     implementations) to be able to enter a user program point
     from anywhere in the run-time system.  However, an implicit
     jump is easier to implement than an implicit procedure call.
     It has the slight drawback that it is difficult to know
     where the error occurred and to proceed after corrections,
     because bookkeeping operations like e.g.  file positioning
     may get out of phase.  It is also not agreed that implicit
     actions are consistent with good programming methodology.

     Method B contradicts i) or ii) and iv) depending on whether
     the additional parameters are made compulsory or optional.
     Moreover, it takes care only of errors in system procedures.
DECsystem-10 SIMULA Language Handbook, part III          Page 147
APPENDIX B - CONTROLLED ERROR HANDLING


     Method C complies with all requirements to a reasonable
     degree.  However, it requires a program to continue after an
     error has occurred and this continued execution will maybe
     not be entirely implementation independent.  It can be seen
     as a method to achieve an orderly failure rather than a
     means to implement a complicated polyalgorithm.  It is easy
     to implement recovery procedures of differing levels of
     detail as in the example:

     BEGIN initialize_sequence_of_batches;
       WHILE more_batches DO
       BEGIN
         process_batch:
         WHILE more_records DO
         BEGIN process_record:
           WHILE more_fields DO
           BEGIN process_field;
             recovery1;
           END;
           recovery2;
         END;
         recovery3;
       END;
     END;

     At each of the recovery points it is possible to prevent
     upward updates from an erroneous field, record or batch.


B.4  Proposal.

     It is suggested that the following text be inserted into the
     SDG publications:

     "Programmed Error Handling.

     The programmed error handling facilities of SIMULA make it
     possible to achieve, in a SIMULA program, an orderly
     handling of certain errors occurring during execution as a
     result of incorrect or unexpected inputs to the program.
     Errors are classified into the following categories:
DECsystem-10 SIMULA Language Handbook, part III          Page 148
APPENDIX B - CONTROLLED ERROR HANDLING


     1   Underflow in floating point computation
     2   Overflow in computation or division by zero
     3   I/O transmission error
     4   End of file error
     5   Edit overflow
     6   Incorrect text contents for de-editing procedure
     7   Array index out of range
     8   Incorrect parameter to mathematical function
     9   Time limit - as defined by a previous call to TIMELIMIT
         - exceeded.
     10  All the errors listed above.
     999999 Remaining errors that can be intercepted in an
         implementation.

     The errors above are not all errors that can result from
     incorrect data but only those that will occur as a direct
     and immediate consequence of invalid data.  Second order
     errors result from following an incorrect path of the
     program because of invalid data:  those errors are not
     handled.

     The following system procedures are available for error
     handling:

     [Addition by Jacob Palme 1976-03] Possibly we could allow an
     implementation to add an implementation dependent number of
     extra error codes, between 11 and 999998.  The error code
     999999 would then be equivalent to all such error codes,
     which means that programs using only error codes 1-8 will
     still be machine independent and programs using error codes
     9, 10 and 999999 will be reasonably machine independent,
     while programs using extra error codes between 11 and 999998
     will at their own risk be machine dependent.

**** PROCEDURE MASKERROR(CODE,COUNT);  INTEGER CODE,COUNT;

     Execution of MASKERROR permits COUNT errors of category CODE
     to occur without intervention by the run time system.  The
     effect of continuing after an error is dependent on the kind
     of error:  (On certain computers, the architecture may make
     these default effects impossible.  If so, they may do
     otherwise.)

     1.  Result of operation is zero.

     2.  Result of operation is zero.
DECsystem-10 SIMULA Language Handbook, part III          Page 149
APPENDIX B - CONTROLLED ERROR HANDLING


     3.  The image fetched will contain the record as
         transmitted, if possible.  Otherwise a blank image will
         be fetched.

     4.  The image will be set to blanks.  ENDFILE will still be
         TRUE if sensed.

     5.  The field of the operation will contain asterisks.

     6.  The result will be zero.

     7.  The first acceptable index (i e the lower bound) will be
         used.  Note that on some implementations the first
         ELEMENT (lower bound everywhere!) may have to be used.

     8.  The result of the function will be zero.

     9.  No action, job continues.

     11-999999. Implementation dependent.

     A new call to MASKERROR resets the previous error count (as
     returned by SENSEERROR).

     If an implementation enters dialog or debug mode in case of
     an error of a category mentioned above, this facility will
     be suppressed by a call to MASKERROR for the category.

     When the program starts, categories 1 and 5 are
     automatically masked by the SIMULA system with a large value
     on COUNT.


**** PROCEDURE JUMPERROR(CODE,L);  INTEGER CODE;  LABEL L;

     Execution of JUMPERROR directs the run time system to make
     an implicit jump to L if an error of category CODE occurs.
     The sequence of operations is interrupted so that no effect
     of the illegal operation remains when L is entered, nor will
     it be possible to find out exactly which operation caused
     the error, except indirectly from the contents of program
     variables.

     The label L must be in the outermost block of the main
     program (recovery for the otherwise possible ILLEGAL GOTO
     may be very difficult or impossible to implement).  From
     this follows that JUMPERROR cannot be called in a separately
     compiled module.  A call to jumperror for other labels than
     in the outermost block should cause an error interrupt.

     Both MASKERROR and JUMPERROR can be called for an error
DECsystem-10 SIMULA Language Handbook, part III          Page 150
APPENDIX B - CONTROLLED ERROR HANDLING


     category, but the last call has effect.

     Dialogue and debug mode recoveries are suppressed by
     JUMPERROR as by MASKERROR.


**** PROCEDURE RESETERROR(CODE);  INTEGER CODE;

     Execution of RESETERROR inhibits the effect of previous
     calls to MASKERROR or JUMPERROR for the category CODE.
     Subsequent errors are intercepted and diagnosed.


**** INTEGER PROCEDURE SENSEERROR(CODE);  INTEGER CODE;

     A call to SENSEERROR returns the number of errors of
     category CODE that have occurred.  If CODE is zero, the
     total number of errors is returned.  SENSEERROR does not
     reset the error counts.


B.5  Discussion.

     This proposal was modified at in October 75 after the SDG
     meeting.  The proposal can be modified in several areas to
     accomplish a different balance between implementability and
     implementation independence:

     The error categories can be made finer or coarser, in
     particular the existence of categories 11-999999 is
     debatable;
     Default settings can be altered;
     One may redefine results of undefined operations;
     One may specify the error categories by reference to the
     sections in the Common Base or Algol report where the error
     is described;
     It is possible to use different system procedures instead of
     having the non-natural assignment of codes to error
     categories;
     These questions are best solved (if the proposal is
     accepted) in the Simula Development Group.
DECsystem-10 SIMULA Language Handbook, part III          Page 151
APPENDIX C - INDEX


APPENDIX C - INDEX
------------------


   ABORT EXTERNAL PROCEDURE  . . . 46
   ABSADR EXTERNAL INTEGER PROCEDURE, address of a variable  108
   Access protection . . . . . . . 138
   Access to memory without checking, LOADBYTE  117
   Access to memory without checking, LOADWORD  117
   Access to memory without checking, STOREBYTE  123
   Access to memory without checking, STOREWORD  124
   Address of a variable, absolute  108
   ADJPTR EXTERNAL INTEGER PROCEDURE (adjust byte pointer)  108
   ADVANCE of magtapes . . . . . . 44
   Alphanumerical display terminal  25
   ALTMODE TTY bit setting from a SIMULA program  125
   ANDINT procedure (bitwise AND between 36-bit words)  108
   APPROX EXTERNAL INTEGER PROCEURE  53
   Arnborg, Stefan . . . . . . . . 145
   Array index range error . . . . 148
   ARRLGD EXTERNAL INTEGER PROCEDURE  86
   ARRTXT EXTERNAL PROCEDURE . . . 86
   ASCII to SIXBIT conversion, SIXBIT procedure  123
   ASCII to SIXBIT conversion, WILDSIX procedure  129
   ATR file structure, SIMATR program  123
   ATRSTR EXTERNAL CLASS, attribute file structure  109
   Attribute file structure, ATRSTR class  109
   Attribute file structure, display by SIMATR program  123

   BACKSPACE of magtapes . . . . . 44
   Binary input/output . . . . . . 38
   Binary to octal conversion, OCTAL procedure  118
   Bit manipulation, ANDINT procedure  108
   Bit manipulation, BITGET procedure  109
   Bit manipulation, BITPUT procedure  109
   Bit manipulation, BOOLFUNC procedure  110
   Bit manipulation, DEPBYTE procededure  113
   Bit manipulation, INTREA procedure  117
   Bit manipulation, LOADBYTE  . . 117
   Bit manipulation, REAINT procedure  122
   Bit manipulation, STOREBYTE . . 123
   BITFIELD EXTERNAL INTEGER PROCEDURE  109
   BITGET EXTERNAL INTEGER PROCEDURE  109
   BITPUT EXTERNAL INTEGER PROCEDURE  109
   Blanks, removal of  . . . . . . 60
   BOKSTAV EXTERNAL BOOLEAN PROCEDURE  107
   BOOLEAN data stored as bit strings  109
   BOOLFUNC EXTERNAL INTEGER PROCEDURE  110
   BREAKOUTLINE EXTERNAL PROCEDURE  87
   BYPASS EXTERNAL BOOLEAN PROCEDURE  42
   Byte handling, BITFIELD procedure  109
   Byte handling, DEPBYTE procedure  113
   Byte handling, STOREBYTE  . . . 123
   Byte manipulation, LOADBYTE procedure  117
   Byte pointer manipulation, ADJPTR procedure  108

   CALLI UUO executed directly from SIMULA, XCALLI procedure  129
   CALLMIC EXTERNAL INTEGER PROCEDURE  110
   CAT demo program, cat and mouse game  27
   CDCSIM Conversion Program . . . 28
   CHANGE EXTERNAL BOOLEAN PROCEDURE  74
   Change partial word, DEPBYTE procedure  113
   Character byte pointer manipulation  108
   Character format transformation from ASCII to SIXBIT  116
   Character input, echo control of  114
   CHARACTER output, direct  . . . 36
   CHECKEXTENSION EXTERNAL TEXT PROCEDURE  113
   CHECKFRAC EXTERNAL INTEGER PROCEDURE  66
   Checking of terminal input data  17
   CHECKINT EXTERNAL INTEGER PROCEDURE  64
   CHECKREAL EXTERNAL INTEGER PROCEDURE  64
   CLOCKTIME EXTERNAL REAL PROCEDURE  32
   CLOSEOPEN EXTERNAL PROCEDURE  . 45
   Codasyl-type Data Base Management  22
   Command input to SIMULA programs, RESCAN procedure  122
   Command interpreter (DEC-10 style), DECOM  83
   Command line scan, SCAN procedure  79
   Communication between programs, TMPIN procedure  124
   Communication between programs, TMPOUT procedure  125
   Communication with monitor, XCALLI (CALLI UUO)  129
   COMPRESS EXTERNAL TEXT PROCEDURE  71
   CONC EXTERNAL TEXT PROCEDURE  . 70
   CONC2 EXTERNAL TEXT PROCEDURE . 70
   Conditions of release . . . . . 2
   CONTROL-C, simulated from program  50
   CONTROLLED ERROR HANDLING.  . . 46
   Conversational I/O  . . . . . . 17
   Conversational system . . . . . 140
   Conversational terminal . . . . 135
   Conversion from ASCII to SIXBIT, SIXBIT procedure  123
   Conversion from ASCII to SIXBIT, WILDSIX procedure  129
   Conversion from binary to octal, OCTAL procedure  118
   Conversion from RADIX50 to ASCII, IDRX50 procedure  116
   Conversion from SIXBIT to ASCII, IDSIXBIT procedure  116
   Conversion programs . . . . . . 28
   Copying of disk files, FILCOPY procedure  114
   Copyright of the SIMULA system  2
   COREGUIDE EXTERNAL BOOLEAN PROCEDURE  53
   CORELIMIT EXTERNAL BOOLEAN PROCEDURE  52
   COSYS, part of FIGURE . . . . . 7
   COSYSF, part of FIGURE  . . . . 7
   CP(U)TIME EXTERNAL REAL PROCEDURE  32
   CRLF TTY bit setting from a SIMULA program  125
   CTRL-C, simulated from program  50
   CTRL-O bit resetting  . . . . . 45
   DAHELP EXTERNAL CLASS . . . . . 26
   Data base handling  . . . . . . 23
   Data Base Management  . . . . . 22
   Data collection, form method  . 27
   Data entry by form fill in  . . 26
   Data transmission errors  . . . 146
   DATE  . . . . . . . . . . . . . 31
   DAYNO EXTERNAL INTEGER PROCEDURE  31
   DAYTIME EXTERNAL TEXT PROCEDURE  32
   DBMMIN, part of SIMDBM system . 23
   DBMS error condition  . . . . . 146
   DBMSET, part of SIMDBM system . 23
   DDTDEM SIMDDT demo program  . . 27
   De-editing procedure error  . . 148
   DEC-style command interpreter, DECOM  83
   DECOM EXTERNAL CLASS, see also SCAN  83
   Deleting a file, RENAME procedure  120
   Deleting files  . . . . . . . . 44
   Demo programs . . . . . . . . . 27
   Demonstration programs  . . . . 27
   DEPBYTE EXTERNAL PROCEDURE  . . 113
   DEPCHAR EXTERNAL PROCEDURE  . . 60
   Desynchronize . . . . . . . . . 133
   Dialogue I/O  . . . . . . . . . 17
   DIMENSIONS EXTERNAL INTEGER PROCEDURE  53
   Direct access files, application package with  23
   Direct access files, text editing of  23
   Direct Access Help files  . . . 26
   DIRECTFILE binary I/O . . . . . 42
   DIRECTFILE HANDLING PROGRAMS  . 30
   Directfile text editing - DIRED  30
   DIRECTFILE to seqeuential file conversion  30
   Directory sorting, SORTDN procedure  99
   DIRED Direct file editor  . . . 23
   DIRED program . . . . . . . . . 30
   DIRHND EXTERNAL CLASS . . . . . 113
   DIRSEQ program  . . . . . . . . 30
   Disk-to-disk copy, FILCOPY procedure  114
   Display terminal  . . . . . . . 25
   Division by zero error  . . . . 148
   DOTYPEOUT EXTERNAL BOOLEAN PROCEDURE  45

   ECHO EXTERNAL PROCEDURE . . . . 114
   ECHO TTY bit setting from a SIMULA program  125
   Edit overflow error . . . . . . 148
   Editing of SIMULA direct access files  23
   ENTERDEBUG EXTERNAL PROCEDURE . 46
   Entry of data by form fill in . 26
   ENVIRONMENT ENQUIRY . . . . . . 53
   Error flags . . . . . . . . . . 146
   ERROR INTERRUPT ROUTINES  . . . 46
   Error recovery  . . . . . . . . 147
   EXIT EXTERNAL PROCEDURE . . . . 50
   EXIT, immediate, from execution  50
   Extracting a field from a 36-bit word, BITFIELD procedure  109
   FETCH.SIM part of SIMDBM  . . . 23
   FETCHAR EXTERNAL CHARACTER PROCEDURE  60
   FIGURE graphic package  . . . . 25
   FILCOPY EXTERNAL INTEGER PROCEDURE  114
   File conversion, to and from directfile  30
   File directory handling, DIRHND class  113
   FILE HANDLING . . . . . . . . . 44
   File lookup, FLOKUP procedure . 115
   File renaming or deletion, RENAME procedure  120
   File specification string, FILSPC procedure  115
   FILENAME EXTERNAL TEXT PROCEDURE  35
   FILL TTY bit setting from a SIMULA program  125
   FILSPC EXTERNAL TEXT PROCEDURE  115
   FINDDIRECTFILE EXTERNAL REF (DIRECTFILE) PROCEDURE  44
   FINDINFILE EXTERNAL REF (INFILE) PROCEDURE  44
   FINDOUTFILE EXTERNAL REF (OUTFILE) PROCEDURE  44
   FINDPRINTFILE EXTERNAL REF (PRINTFILE) PROCEDURE  44
   FINDTRIGGER EXTERNAL CHARACTER PROCEDURE  62
   Flags, marking errors . . . . . 146
   Floating point error  . . . . . 148
   FLOKUP EXTERNAL INTEGER PROCEDURE  115
   FORCEOUT EXTERNAL PROCEDURE . . 37
   Form fill in data entry . . . . 26
   FORM form fill in data entry package  26
   Form method of data collection  27
   FORM package, test programs . . 27
   FORM TTY bit setting from a SIMULA program  125
   FORSIM EXTERNAL PROCEDURE . . . 46
   FORTRAN programming language  . 146
   FQC Program measurement system  29
   FREEBITS EXTERNAL INTEGER PROCEDURE  51
   FREEZE EXTERNAL PROCEDURE . . . 49
   FROM EXTERNAL TEXT PROCEDURE  . 59
   FRONT EXTERNAL TEXT PROCEDURE . 59
   FRONTCOMPARE EXTERNAL BOOLEAN PROCEDURE  63
   FRONTSTRIP EXTERNAL TEXT PROCEDURE  60

   GAG TTY bit setting from a SIMULA program  125
   Game of cat and mouse . . . . . 27
   Garbage collection  . . . . . . 51
   General Purpose System Simulator (GPSS) in SIMULA  24
   GETCH EXTERNAL CHARACTER PROCEDURE  36
   GETITEM EXTERNAL TEXT PROCEDURE  60
   GETRADIX EXTERNAL INTEGER PROCEDURE  85
   GETTAB EXTERNAL PROCEDURE . . . 116
   Getting information from another program, TMPIN procedure  124
   GETTYPE EXTERNAL INTEGER PROCEDURE  66
   GETVIS terminal type enquirer . 26
   GPSSS system written in SIMULA  24
   GRAPHI, part of FIGURE  . . . . 7
   Graphic package for tektronix terminals  25

   HASH EXTERNAL INTEGER PROCEDURE  66
   Help facility in user programs  17
   HELP facility, package for providing of  26
   Hibernate . . . . . . . . . . . 133
   HISTP EXTERNAL PROCEDURE  . . . 90

   I/O transmission error  . . . . 148
   IASHIFT EXTERNAL BOOLEAN PROCEDURE  101
   IBMSIM Conversion Program . . . 28
   IDRX50 EXTERNAL TEXT PROCEDURE  116
   IDSIXBIT EXTERNAL TEXT PROCEDURE  116
   ILOG EXTERNAL INTEGER PROCEDURE  94
   IMAX EXTERNAL INTEGER PROCEDURE  58, 101
   IMIN EXTERNAL INTEGER PROCEDURE  58, 101
   IMPLEMENTATION EXTERNAL TEXT PROCEDURE  53
   Information Retrieval . . . . . 24
   INITEM EXTERNAL TEXT PROCEDURE  61
   INLINE EXTERNAL TEXT PROCEDURE  88
   INORD EXTERNAL TEXT PROCEDURE . 107
   Input data checking . . . . . . 17
   INPUT EXTERNAL INTEGER PROCEDURE  39, 41
   Input of characters from terminal, control of echoing  114
   Input of data by form fill in . 26
   Input-Output errors . . . . . . 146
   INPUT/OUTPUT  . . . . . . . . . 35, 87
   INPUTCHECK EXTERNAL BOOLEAN PROCEDURE  33
   INPUTWAIT EXTERNAL INTEGER PROCEDURE  34
   INSINGLECHAR EXTERNAL CHARACTER PROCEDURE  35
   INSNGL EXTERNAL CHARACTER PROCEDURE  36
   INTEGER to REAL conversion, REAINT procedure  122
   Intra-job communication, TMPIN procedure  124
   Intra-job communication, TMPOUT procedure  125
   INTREA EXTERNAL PROCEDURE . . . 117
   ISUM EXTERNAL INTEGER PROCEDURE  94

   Job control . . . . . . . . . . 118
   Job control, JOBSTATUS procedure  117
   Job control, PTYCHECK procedure  119
   Job control, PTYFIL procedure . 120
   Job control, PTYINIMAGE procedure  120
   JOBSTATUS EXTERNAL INTEGER PROCEDURE  117
   JUMPERROR procedure . . . . . . 149

   LASTLOC EXTERNAL INTEGER PROCEDURE  45
   Line-numbered file, input of  . 118
   LINECOUNT EXTERNAL INTEGER PROCEDURE  35
   LITENBOKSTAV EXTERNAL TEXT PROCEDURE  107
   LMAX EXTERNAL LONG REAL PROCEDURE  58
   LMIN EXTERNAL LONG REAL PROCEDURE  58
   LOAD.SIM part of SIMDBM . . . . 23
   LOADBYTE EXTERNAL INTEGER PROCEDURE  117
   LOADWORD EXTERNAL INTEGER PROCEDURE  117
   LOGININFORMATION EXTERNAL TEXT PROCEDURE  54
   LOOK EXTERNAL BOOLEAN PROCEDURE  43
   LOOKAHEAD EXTERNAL CHARACTER PROCEDURE  87
   LOOKUP EXTERNAL BOOLEAN PROCEDURE  68
   LOOKUP of files . . . . . . . . 44
   LOWCASE EXTERNAL TEXT PROCEDURE  71
   LSUM EXTERNAL LONG REAL PROCEDURE  94

   MAKEDF program  . . . . . . . . 30
   MAKETEXT EXTERNAL TEXT PROCEDURE  71
   MAKHLP PROGRAM generating DAHELP files  30
   MASKERROR procedure . . . . . . 148
   MATCH6 EXTERNAL INTEGER PROCEDURE  117
   Mathematical function error . . 148
   Max and min, IMAX procedure . . 58
   Max and min, IMIN procedure . . 58
   Max and min, LMAX procedure . . 58
   Max and min, LMIN procedure . . 58
   Max and min, RMAX procedure . . 58
   Max and min, RMIN procedure . . 58
   MAXINT EXTERNAL INTEGER PROCEDURE  53
   MAXLOC EXTERNAL INTEGER PROCEDURE  45
   MAXREAL EXTERNAL LONG REAL PROCEDURE.  53
   Memory access without SIMULA checks, LOADBYTE  117
   Memory access without SIMULA checks, LOADWORD  117
   Memory access without SIMULA checks, STOREBYTE  123
   Memory access without SIMULA checks, STOREWORD  124
   MEMORY HANDLING . . . . . . . . 51
   MENU EXTERNAL BOOLEAN PROCEDURE  67
   MENY EXTERNAL BOOLEAN PROCEDURE  107
   MIC control from a SIMULA program, CALLMIC procedure  110
   MIN AND MAX . . . . . . . . . . 58
   Min and max, IMAX procedure . . 58
   Min and max, IMIN procedure . . 58
   Min and max, LMAX procedure . . 58
   Min and max, LMIN procedure . . 58
   Min and max, RMAX procedure . . 58
   Min and max, RMIN procedure . . 58
   MINREAL EXTERNAL LONG REAL PROCEDURE  53
   Monitor calls from SIMULA, XCALLI procedure  129
   Monitor tables, GETTAB procedure  116
   Monitoring  . . . . . . . . . . 143
   Multi-terminal  . . . . . . . . 138

   Network, TTYLINE procedure  . . 127
   Network, TTYNUMBER procedure  . 128
   NEXTRANDOM EXTERNAL PROCEDURE . 104
   NO (FORM, CRLF, GAG, TAB etc.) TTY bit setting  125
   Number on input line  . . . . . 118
   NUMBERED EXTERNAL BOOLEAN PROCEDURE  118

   Object input/output . . . . . . 38
   OCTAL EXTERNAL TEXT PROCEDURE . 118
   ON condition in PL/1  . . . . . 145
   OPERATIONS ON TEXTS . . . . . . 69
   OUTCHR EXTERNAL PROCEDURE . . . 36
   OUTLINE EXTERNAL PROCEDURE  . . 87
   OUTPUT EXTERNAL INTEGER PROCEDURE  39
   Output of CHARACTER immediately  36
   Output of TEXT immediately  . . 37
   Output, forced, to the TTY  . . 37
   OUTSTRING EXTERNAL PROCEDURE  . 37
   OUTTIME EXTERNAL PROCEDURE  . . 90
   Overflow error  . . . . . . . . 148

   PACK EXTERNAL BOOLEAN PROCEDURE  54
   PACKING INTO PARTS OF WORDS . . 54
   Parallel processes in the real world  142
   PARTITIONING OF TEXTS . . . . . 59
   PERGEN EXTERNAL CLASS . . . . . 102
   Picture processing  . . . . . . 25
   PL/1 programming language . . . 145
   PREP1.SIM part of SIMDBM  . . . 23
   Preprocessor in SIMDBM producing SIMULA classes  23
   PRIMARY MEMORY HANDLING . . . . 51
   Process control . . . . . . . . 142
   Program measurement system FQC  29
   PTY handling  . . . . . . . . . 118
   PTY handling, JOBSTATUS procedure  117
   PTY handling, PTYCHECK procedure  119
   PTY handling, PTYFIL procedure  120
   PTY handling, PTYINIMAGE procedure  120
   PTYCHECK EXTERNAL INTEGER PROCEDURE  119
   PTYFIL EXTERNAL INTEGER PROCEDURE  120
   PTYINIMAGE EXTERNAL INTEGER PROCEDURE  120
   PUTFLOAT EXTERNAL TEXT PROCEDURE  77
   PUTSIZE EXTERNAL INTEGER PROCEDURE  42
   PUTTEXT EXTERNAL BOOLEAN PROCEDURE  70
   PUTTIME EXTERNAL TEXT PROCEDURE  75

   QASETE question-answering demo program  27
   QSIM demo program, doctor's waiting room  27
   Question-answering demo program  27
   QUEUE system simulation using GPSSS  24

   RADIX EXTERNAL TEXT PROCEDURE . 84
   Radix50 conversion, RDX50 procedure  121
   RADIX50 to ASCII conversion, IDRX50 procedure  116
   RADIX50 to SIXBIT code, SXRX50 procedure  123
   RANDOM EXTERNAL REAL PROCEDURE  103
   RANDOM NUMBER GENERATION ETC. . 102
   Range error for array index . . 148
   RDX50 EXTERNAL PROCEDURE  . . . 121
   Reaction time . . . . . . . . . 140
   READ errors . . . . . . . . . . 146
   READ EXTERNAL PROCEDURE . . . . 37
   REAINT EXTERNAL PROCEDURE . . . 122
   REAL to INTEGER conversion, INTREA procedure  117
   REAL-TIME FOR MULTI-TERMINAL SIMULTANEOUS I/O.  32
   REALTIME EXTERNAL SIMULATION CLASS  130
   Receiving information from another program, TMPIN procedure  124
   Record input/output . . . . . . 38
   Recovery after error  . . . . . 145
   REL file information, RDX50 procedure  121
   Release version . . . . . . . . 1
   RENAME EXTERNAL INTEGER PROCEDURE  120
   Renaming a file, RENAME procedure  120
   REQUEST EXTERNAL TEXT PROCEDURE  88
   RESCAN EXTERNAL BOOLEAN PROCEDURE  122
   Reseterror procedure  . . . . . 150
   Responsibility for errors . . . 2
   REST EXTERNAL TEXT PROCEDURE  . 59
   RESTORE EXTERNAL PROCEDURE  . . 49
   REWIND of magtapes  . . . . . . 44
   RMAX EXTERNAL REAL PROCEDURE  . 58
   RMIN EXTERNAL REAL PROCEDURE  . 58
   ROUTINES WRITEABLE IN SIMULA. . 59
   RSUM EXTERNAL REAL PROCEDURE  . 94
   RUBOUT, part of FIGURE  . . . . 7
   RUN EXTERNAL PROCEDURE  . . . . 47

   SAFEI EXTERNAL CLASS  . . . . . 22
   SAFEIO conversational i/o package  17
   SAFEIO EXTERNAL CLASS . . . . . 17
   SAFMIN EXTERNAL CLASS . . . . . 22
   SAVE EXTERNAL INTEGER PROCEDURE  48
   SCALESTEP EXTERNAL REAL PROCEDURE  100
   SCAN EXTERNAL INTEGER PROCEDURE, see also DECOM  79
   SCANFRAC EXTERNAL INTEGER PROCEDURE  70
   SCANINT EXTERNAL INTEGER PROCEDURE  69
   SCANREAL EXTERNAL LONG REAL PROCEDURE  69
   SCANTO EXTERNAL TEXT PROCEDURE  62
   SCHEDULING AND JOB CONTROL  . . 47
   SCHEMA, entering into a data base  23
   SCRAMBLE EXTERNAL PROCEDURE . . 102
   SCRATCHFILE EXTERNAL BOOLEAN PROCEDURE  44
   Scratching a file, RENAME procedure  120
   Scratching files  . . . . . . . 44
   SEARCH EXTERNAL INTEGER PROCEDURE  63
   Search with Boolean condition . 24
   SEARCHING AND TESTING OF TEXTS  62
   Segmentation into overlayed core code segments  52
   SELECT EXTERNAL CLASS . . . . . 24
   Semaphore . . . . . . . . . . . 142
   Sending information to another program, TMPOUT procedure  125
   SENSEERROR procedure  . . . . . 150
   Sequentail file to DIRECTFILE conversion  30
   SET TTY performed from a SIMULA program  125
   SFD sorting, SORTDN procedure . 99
   SFD-file handling . . . . . . . 113
   SHIP demo program, troup transport simulation  27
   SIGMA2 EXTERNAL REAL PROCEDURE  95
   SIGMEAN EXTERNAL PROCEDURE  . . 96
   SIMATR program for displaying attribute files  123
   SIMDBM data base query system . 23
   SIMDBM files on the distribution tape  23
   SIMDBM system . . . . . . . . . 22
   SIMDBM, ARRLGD utility procedure  86
   SIMDBM, ARRTXT utility procedure  86
   SIMDBM, class DBMMIN  . . . . . 23
   SIMDBM, class FETCH.SIM . . . . 23
   SIMDBM, routine LOAD.SIM  . . . 23
   SIMDBM, routine PREP1.SIM . . . 23
   SIMDDT demo program DDTDEM  . . 27
   SIMDDT, procedure for calling . 46
   SIMDEM demo programs  . . . . . 27
   SIMED SIMULA Program Editor . . 28
   SIMEI EXTERNAL SIMULATION CLASS  22
   SIMEIO EXTERNAL SIMULATION CLASS  22
   SIMEXP program for merging source files  28
   SIMIBM Conversion Program . . . 28
   SIMMIN EXTERNAL SIMULATION CLASS  22
   SIMSTR SIMULA PROGRAM Stripper  28
   SIMULA SOURCE PROGRAM CONVERSION PROGRAMS  28
   Simulation demo program . . . . 27
   Simulation of cat and mouse game  27
   Simulation of doctor's waiting room  27
   Simulation of troup transport . 27
   SIXBIT EXTERNAL INTEGER PROCEDURE  123
   SIXBIT from RADIX50, SXRX50 procedure  123
   SIXBIT match with "wildcards", MATCH6 procedure  117
   SIXBIT to ASCII conversion, IDSIXBIT procedure  116
   SKIP EXTERNAL TEXT PROCEDURE  . 63
   SLEEP EXTERNAL PROCEDURE  . . . 34
   SORT PROCEDURES . . . . . . . . 97
   SORTDN EXTERNAL PROCEDURE for sorting 2-dim integer array  99
   Sorting a 2-dimensional integer array, SORTDN procedure  99
   SORTING AND SUMMATION ETC.  . . 94
   SORTTA EXTERNAL PROCEDURE . . . 97
   SORTTD EXTERNAL PROCEDURE . . . 98
   SPLIT EXTERNAL PROCEDURE  . . . 72
   SPLITA EXTERNAL INTEGER PROCEDURE  73
   SPLITC EXTERNAL INTEGER PROCEDURE  73
   SQHELP EXTERNAL BOOLEAN PROCEDURE  26
   SSCAN version of SCAN . . . . . 83
   STARTPOS EXTERNAL INTEGER PROCEDURE  72
   STAT1E simulation demo program  27
   STAT2E simulation demo program  27
   Status query  . . . . . . . . . 143
   STOP, immediate, of execution . 50
   STORBOKSTAV EXTERNAL TEXT PROCEDURE  107
   STORE data base handling package  23
   STOREBYTE EXTERNAL INTEGER PROCEDURE  123
   STOREWORD EXTERNAL INTEGER PROCEDURE  124
   Structure of a SIMULA program, output of  123
   Structured programming  . . . . 27
   Subjob control  . . . . . . . . 118
   Subjob control, JOBSTATUS procedure  117
   Subjob control, PTYCHECK procedure  119
   Subjob control, PTYFIL procedure  120
   Subjob control, PTYINIMAGE procedure  120
   SUBMIT EXTERNAL BOOLEAN PROCEDURE  48
   SUMMARY LIST OF ROUTINES  . . . 7
   SWAP EXTERNAL PROCEDURE . . . . 52
   SWEDISH LANGUAGE TEXT HANDLING AND INPUT/OUTPUT  107
   SXRX50 EXTERNAL INTEGER PROCEDURE  123
   Synchronize . . . . . . . . . . 133

   TAB TTY bit setting from a SIMULA program  125
   TABLE package, test of formula data collection  27
   TAGORD EXTERNAL TEXT PROCEDURE  107
   TAGTYP EXTERNAL INTEGER PROCEDURE  107
   Tektronix terminal graphics package  25
   Terminal character input, control of echoing  114
   Terminal communication, TRMOP procedure  125
   Terminal input data checking  . 17
   Terminal type enquiry . . . . . 26
   Test programs . . . . . . . . . 27
   Text editing of SIMULA direct access files  23
   Text editing on directfiles . . 30
   TEXT handling . . . . . . . . . 59
   Text transformation from ASCII to SIXBIT  116
   Text value comparison . . . . . 63
   TIME AND DATE . . . . . . . . . 31
   TIMELIMIT EXTERNAL PROCEDURE  . 32
   TMP:TRM file containing terminal type identification  26
   TMPCOR input, TMPIN procedure . 124
   TMPCOR output, TMPOUT procedure  125
   TMPIN EXTERNAL TEXT PROCEDURE . 124
   TMPNAM EXTERNAL TEXT PROCEDURE  124
   TMPOUT EXTERNAL BOOLEAN PROCEDURE  125
   TODAY EXTERNAL TEXT PROCEDURE . 31
   TOPS-10 directory file handling, DIRHND class  113
   Transferring control to another program, RUN procedure  47
   Transmission of data, errors  . 146
   TRMOP EXTERNAL INTEGER PROCEDURE  125
   TSUB EXTERNAL TEXT PROCEDURE  . 60
   TTY (.SET TTY) performed from a SIMULA program  125
   TTY line number in DEC-10 network, TTYLINE procedure  127
   TTY number in DEC-10 network, TTYNUMBER procedure  128
   TTYCHECK EXTERNAL BOOLEAN PROCEDURE  36
   TTYLINE external procedure  . . 127
   TTYNUMBER external procedure  . 128
   Type conversion, INTREA procedure  117
   Type conversion, REAINT procedure  122

   UFD sorting, SORTDN procedure . 99
   UFD-file handling . . . . . . . 113
   Unchecked memory access, LOADBYTE procedure  117
   Unchecked memory access, LOADWORD  117
   Unchecked memory access, STOREBYTE  123
   Unchecked memory access, STOREWORD  124
   Underflow error . . . . . . . . 148
   UNFORMATTED (BINARY) I/O. . . . 38
   Unformatted input/output  . . . 38
   UNIQUE EXTERNAL INTEGER PROCEDURE  103
   UNLOAD of magtapes  . . . . . . 44
   UNPACK EXTERNAL BOOLEAN PROCEDURE  54
   Unpacking a field from a 36-bit word, BITFIELD procedure  109
   Unrestricted access to core, ABSADR procedure  108
   UPCASE EXTERNAL TEXT PROCEDURE  71
   UPCOMPARE EXTERNAL BOOLEAN PROCEDURE  63
   UPTO EXTERNAL TEXT PROCEDURE  . 59
   UTILITY PACKAGES  . . . . . . . 17

   VIRTUAL MEMORY HANDLING . . . . 52
   VIRTUAL MEMORY HANDLING (OR OVERLAY FACILITY)  52
   VISTA EXTERNAL CLASS  . . . . . 25
   VISTA package, applications . . 27

   Wait  . . . . . . . . . . . . . 133
   Wild card match, MATCH6 procedure  117
   WILDSIX EXTERNAL INTEGER PROCEDURE  129
   WRITE errors  . . . . . . . . . 146
   WRITE EXTERNAL PROCEDURE  . . . 38

   XCALLI EXTERNAL INTEGER PROCEDURE  129

   ZIMSET EXTERNAL CLASS (SIMSET)  105
   ZIMULATION EXTERNAL CLASS (SIMULATION)  105

   ^C, simulated from program  . . 50
   ^O bit resetting  . . . . . . . 45