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                               SECTION  1

                              New Features

This section describes  changes and additions  to Sail since  the August
1976 manual, AIM-289.

1.1 - Double Precision

Double  precision  floating-point  arithmetic  is  available.   Use  the
<type!qualifier> LONG in declarations.  For example,
        LONG REAL X, Y, Z;
        LONG REAL ARRAY XA[0:N];

Currently LONG has  meaning only when it  appears as part of  LONG REAL.
(At some future time LONG INTEGERs may also exist.)

The runtime routines  LREALIN and LREALSCAN  operate the same  as REALIN
and REALSCAN, except for  returning LONG REAL values.  The  routine CVEL
takes a LONG REAL value and returns a string representation like that of
CVE,  except that  "@@"  is used  to  signify LONG  when  delimiting the
exponent.   Any  of  "@",  "@@", "E",  or  "D"  are  acceptable exponent
delimiters to LREALIN and LREALSCAN.

Variables which are declared LONG REAL are represented in  KI10 hardware
format  double precision,  take two  consecutive words  of  storage, and
provide  62  bits  of precision  (approximately  18  decimal  digits) to
represent the  fraction part of  a floating-point number.   Regular REAL
variables occupy a  single word and have  27 bits (8 decimal  digits) of
precision.  The exponent range of  both REAL and LONG REAL  variables is
from -128 to 127, where 2^127 is approximately 10^38.

LONG REAL is a dominant type in arithmetic operations +-*/%^ MAX MIN and
arithmetic relationals  <>= LEQ GEQ  NEQ.  If one  operand is  LONG REAL
then both operands will be converted to LONG REAL (if  necessary) before
performing  the  operation.   An exponentiation  involving  a  LONG REAL
raised to a positive integer constant is an exception to this rule.  The
type coercion path is linear:   STRING -> INTEGER -> REAL ->  LONG REAL.
Conversion from REAL to LONG  REAL is performed by assigning  the (only)
word of  the REAL  to the  most significant  word of  the LONG  REAL and
setting the second  (least significant) word of  the LONG REAL  to zero.
Conversion from LONG REAL to REAL is by UUO which rounds.

Arithmetic and assignment operations are compiled into DFAD, DFSB, DFMP,
DFDV, DMOVE,  DMOVEM instructions.  The  Sail operations ASH,  LSH, ROT,
LAND, LOR,  EQV, XOR are  performed on both  words (ASHC, LSHC,  ROTC, 2
ANDs, 2 IORs, etc.).  LOCATION of a LONG REAL variable gives  an address
E such that  DMOVE AC,E fetches the  appropriate words of  memory.  When
passed by value  as an actual parameter  to a procedure, both  words are
placed on  the P stack:   PUSH P,X  ; PUSH P,X+1.   LONG REAL  fields in
record  classes are  handled much  like STRING  fields, except  that the
address in the record field points  to the first word of a  2-word block
(rather than to the second word as in the case with STRINGs).

LONG  REAL ARRAYs  are  stored as  contiguous blocks  of  2-word values.
ARRTRAN done on two LONG REAL arrays is a transparent operation, but for
ARRYIN, ARRYOUT,  or ARRBLT  the actual word  count is  specified; think
about whether you should multiply by 2!  At runtime the array descriptor
for a LONG ARRAY has bit  12 (40,,0 bit) set in MULT(n),  the multiplier
for the last dimension (which would otherwise be =1).  Similarly, a LONG
ARRAY is allocated by setting bit 12 (40,,0) bit in the  parameter which
specifies the number of dimensions to ARMAK.

Runtime support for LEAP items with LONG REAL datums does not yet exist,
although the compiler does generate suitable code.  Runtime  support for
double precision  exponentiation is  also limited  for the  moment.  Any
exponentiation X^K where  K is a  positive integer constant  is compiled
inline using  the binary ("Russian  peasant") method, regardless  of the
type  of  X.   Other exponentiations  involving  LONG  REALs  are merely
translated into procedure calls on


depending on the type of the exponent.  The Sail runtime system does not
yet contain such procedures, so you will have to roll your own.

1.2 - Declarations and Scope

Sail declarations must occur before use.  For example, in  the following
program the argument to  PRINT is interpreted as  the K on line  2, even
though by the ALGOL60 notion of scope it should be interpreted as  the K
on line 5.

        BEGIN "FOO"
        INTEGER K;      COMMENT this is line 2;
          BEGIN "RUB"
          INTEGER K;    COMMENT this is line 5;
          END "RUB"
        END "FOO"

1.3 - Two-character Operators

The compiler now recognizes "**" for "^", ":=" for "_", "<="  for "LEQ",
and ">=" for "GEQ".

1.4 - Requires

REQUIRE  OVERLAP!OK;   will  suppress  the   message  which   occurs  at
initialization when two programs have declared items.

REQUIRE VERIFY!DATUMS; causes the compiler to generate  three additional
instructions for each DATUM reference, to make sure (dynamically, at run
time) that the type  of the item in the  DATUM construct is the  same as
the compiler expected.  This is similar to (the unimplimented effect of)
declaring all itemvars CHECKED.   It is planned that  VERIFY!DATUMS will
soon be a bit in the  /A switch and that the corresponding  REQUIRE will

REQUIRE   PROCESSES;  insures   that  MAINPR,   the  main   process,  is
initialized.  You  need not  specify this  REQUIRE if  you use  APPLY or
SPROUT, but if  the only use  of processes is  via INTSET then  you must

1.5 - CASE statement

In an explicitly numbered CASE statement the word ELSE can  appear where
a bracketed case number  is normally used.  The statement  following the
ELSE  is  a  catch-all  for any  case  number  not  mentioned, including
anything  which  would  otherwise  generate  a  CASE  index  error.  For

        CASE K OF BEGIN [3] J_3; ELSE J_4; [5] J_5 END

is another way of accomplishing

             IF K=3 THEN J_3
        ELSE IF K=5 THEN J_5
        ELSE J_4

A CASE statement containing an ELSE case does not generate a call to the
CSERR runtime routine, and  in addition the jump table  usually contains
only max_case - min_case +1 words (rather than max_case +1).

1.6 - Circular RECORD!CLASSes

To  define  two record  classes,  both of  which  contain RECORD!POINTER
fields refering to the other class, say


In general, declare one class to be FORWARD and list  its RECORD!POINTER
fields as pointers to ANY!CLASS.  This breaks the circularity and allows
maximum compile-time type checking.

                               SECTION  2

                          Support for Tops-20

The "Tenex" version of SAIL has been modified slightly to  support Tops-
20.  In  general SAIL  should work  the same  on Tops-20  as it  does on
Tenex.  In particular, both the compiler and compiled SAIL  programs can
be moved between vanilla Tenex  and Tops-20 sites and do  the equivalent
things.   This  is possible  because  all tests  for  Tops-20  or Tenex-
specific code are  made at run-time.  Code  for both will be  present in
all Tenex versions.

The one exception to this happy picture is with runtimes that  are named
after JSYS's and are documented  as simply doing that JSYS.   SAIL makes
no attempt  to insulate you  from subtle differences  in the  meaning of
bits, or the  fact that some of  the JSYS's do not  exist in one  of the
systems.  The  most infamous  of these  problems is  the removal  of the
STDIR JSYS in Tops-20.  That  means that SAIL programs using  STDIR will
blow up on Tops-20. (However  similar results may be obtained  using the
RCDIR  and RCUSR  routines, which  support the  corresponding  JSYS's in

The following  differences in  behavior follow from  the desire  to make
SAIL on Tops-20 look like a "real" Tops-20 system:

     The SAIL compiler's command scanner has been totally rewritten
          for  Tops-20.  The  old scanner  will still  be  used for
          Tenex.  The most important feature of the new  scanner is
          that it  links properly to  the EXEC's  commands COMPILE,
          EXECUTE, LOAD,  and DEBUG.   Note that  in order  to make
          DEBUG work, /BAIL:17 is forced for all  compilations done
          with the  EXEC commands.  The  DEBUG command  then causes
          the  program  to be  loaded  with BAIL  and  a breakpoint
          inserted at the start of the program.

     If you run SAIL  explicitly, you will find that  the top-level
          parser follows the conventions of recent  Tops-20 command
          interpreters.   It  will  expect a  list  of  source file
          names, just as the Tenex one did, but switches are on the
          same  line, rather  than appearing  as  subcommands.  The
          switch names have been lengthened for readability, but we
          trust no  one will  have trouble  matching the  new names
          with the manual.  Arguments are now put after  the switch
          name and  a colon,  as usual.   Instead of  ^R and  ^L to
          select  the  output  file  names,  the  switches /BINARY,
          /LIST,  and  /CREF  can  optionally  take  file  names as
          arguments.   To  suppress  creation  of  an  output file,
          specify /NOBINARY, /NOLIST,  or /NOCREF.  The  default is
          /BINARY/NOLIST, as with Tenex.  Switches that  took octal
          numbers  to specify  sets of  features now  allow keyword
          arguments.   If  you  do  not  find  the  new  form self-
          explanatory with a bit of  usage of ?, you can  still use
          the old octal numbers.

     On  Tenex,  certain files  are  expected to  be  on  <SAIL> or

          <SUBSYS>.   The  most important  examples  are <SAIL>T-6-
          SAISG8.SAV  and  <SUBSYS>LOADER.SAV.   On  Tops-20,  such
          files are  looked for  on logical  devices SAI:  and SYS:
          respectively.   It is  assumed that  any site  using SAIL
          will  define  SAI:  as  a  system-wide   logical  device,
          probably referring to  PS:<SAIL>.  By using  SAI: instead
          of <SAIL>, we allow  users to redefine SAI:,  for testing
          private versions of  the sharable segment, etc.   It also
          means that it is not necessary to have a  separate <SAIL>
          directory on each mountable structure, as would be needed
          if <SAIL>  were used.  Also,  files having  the extension
          .SAV on Tenex are assumed to have .EXE on  Tops-20.  E.g.
          the sharable  segment is gotten  from SAI:T-6-SAISG8.EXE,
          and the loader from SYS:LINK.EXE.

     On Tops-20,  the default  line-editors for  TTY input  use the
          RDTTY  JSYS.   RDTTY  will  be  used  whether   the  user
          specifies  the  "Tenex-style"  or  "Tops-10  style"  line
          editor, since RDTTY is  sort of a merging of  features of
          both.   The RDTTY  JSYS implements  the  standard Tops-20
          editing characters, for which we refer you to DEC's Tops-
          20 User's Guide.

In  some cases,  user  programs may  wish to  determine  which operating
system they are running on.  At startup time, the SAIL  runtimes execute
a special GETTAB  UUO that is supposed  to return a code  indicating the
operating system.   This GETTAB  is implemented  on all  known operating
systems  that use  PDP-10  hardware, except  for the  Stanford  A.I. Lab
monitor, and  possible certain  out-of-date Tenex  systems.  It  is even
implemented on ITS!  The value returned by this UUO is put in a variable
$OS, which may be declared as an EXTERNAL INTEGER by your program so you
can look at it.  The codes are returned in bits 18-23:

        1 - Tops-10
        2 - ITS
        3 - Tenex
        4 - Tops-20
        5 - Stanford A.I. Lab monitor

The other bits in this  word are reserved for indicating  subversions of
these various operating systems.

For  the  Tenex SAIL  system  only, there  is  another  EXTERNAL INTEGER
variable, $OSTYP.  This is set to  0 for Tenex and 2 for  anything else.
This is the variable actually used by the runtimes to  determine whether
to execute Tenex or Tops-20 code.

2.1 - New runtimes for Tops-20

In an effort to  support programming on Tops-20, the  following runtimes
have been added.   Note that they will  result in errors if  executed on
Tenex systems, since  they call JSYS's that  do not exist on  Tenex.  No
attempt is made to prevent  these errors, on the theory that  some Tenex
system might  decide to  implement one  of them.   So we  recommend that
these  be used  only in  programs that  test $OS  or $OSTYP  and provide
special code for both Tenex and Tops-20.

*******************************  ACCES  ******************************;


This runtime calls the ACCES JSYS. It gives the specified job  access to
the requested directory.  Only the first argument is required.  Defaults

     Password null

     Flags    '400 000 000 000 (Connect)

     Jobno    the current job.

Note that because of the  implementation of defaults in SAIL, it  is not
possible to specify a jobno of  0.  However on Tops-20 job 0 is  part of
the operating system, so this does not seem to be a  serious limitation.
(A SAIL  program running as  part of job  0 would of  course be  able to
specify the current job.)

FLAGS are:

     '400 000 000 000   Equivalent to CONNECT monitor command

     '200 000 000 000   Equivalent to ACCESS monitor command

     '100 000 000 000   Equivalent to END-ACCESS monitor command

JOBNO  is the  number of  the  job, or  -1 for  current  job.  (Requires
privileges to set for other jobs).

On success, returns  true; on failure, false,  with TENEX error  code in

*******************************  RCDIR  ******************************;


This  procedure calls  the  RCDIR JSYS.   A 36-bit  directory  number is
returned  as  the  value of  the  call  and also  put  in  the reference
parameter  DIRNO   (useful  for   stepping  through   directories).   If
recognition is not specifically disabled, the reference string DIRECTORY
is updated.

Input FLAGS are:

     '10 000 000   Allow partial recognition

      '4 000 000   Step  to  next  directory  in   group  (Previous
                    directory   number   is  in   DIRNO,   and  the
                    "wildcard" bit must be set)

      '2 000 000   Allow wildcards in "DIRECTORY"

      '1 000 000   Match    given   string    exactly   (suppresses

The flags  returned by the  monitor are put  in the  reference parameter

On failure, zero is returned with !SKIP! set to:

     1   string does not match

     2   string is ambiguous

     3   no more in this group (while stepping)

On error,  zero is  returned with !SKIP!  set to  the TENEX  error code.
(Note the subtle difference  here:  an error involves an  illegal format
for a  directory name, or  some other invalid  argument.  Such  an error
generates a Tenex error code of the usual sort.  A directory  name which
is valid,  but just does  not happen  to exist on  this system  does not
generate a Tenex error code, but is simply called a failure.)

*******************************  RCUSR  ******************************;


This translates a user name  string to its corresponding user  number in
the identical manner as RCDIR does for directory strings.  See RCDIR for
details.  Note  that a valid  directory name always  has < >  around it,
while a user name does not.

*******************************  RSCAN  ******************************;


This procedure calls the RSCAN JSYS.  This allows the program to replace
the string in the rescan buffer, set input to come from that  buffer, or
determine how many characters are still to be read from that buffer.

Both arguments are optional.  If omitted, the values used are

     function 0

     string null

The values of FUNCTION mean:

     0   Set input to come from the rescan buffer.

     1   Return number  of characters  still to  be read  from that

The value returned by the call is the number of characters in the buffer
for FUNCTION 0, and number of characters left for FUNCTION 1.

If STRING is non-null, FUNCTION is ignored, the string is placed  in the
rescan  buffer, and  the value  returned  by the  call will  be  true on

On failure or  error, zero is  returned and !SKIP!  is set to  the TENEX
error code.

******************************  ERSTRING  ****************************;


This is similar to ERSTR.   It will get the error  message corresponding
to  the  given error  number  on  the given  fork.   However  instead of
printing it on the terminal, as  ERSTR does, it returns it as  a string.
!SKIP! will  be set if  the error  number is illegal.   In that  case no
guarantee is  made about what  is returned.  ERRNO  and FORKNO  are both
optional.  The default values are the most recent error (-1)  for ERRNO,
and the current fork for FORKNO.

2.2 - Changes to existing procedures to support Tops-20

*******************************  CLOSF  ******************************;

CLOSF  now takes  an  optional extra  argument,  CLOSF(chan,bits).  This
argument is an integer.  Its left  half will be put in the left  half of
AC1 in the  CLOSF jsys.  The most  useful option is  bit '4 000 000 000.
This  specifies that  the  file is  to  be aborted,  rather  than closed
normally.  If the  file is on  disk, it will  not appear (unless  it has
been closed and reopened).   If it is on tape,  the 2 EOF's will  not be

Note  that  the  SAIL  runtimes have  a  strange  habit  of  closing and
reopenning files, to try to get read/write mode.  If you want to be able
to abort creation of a file, you will have to open it "RW".  If  you do,

then CLOSF with bit '4000000000 set will cause it not to show up on disk
at all.   If you  had specified only  "W", SAIL  would have  created the
file, closed it, and reopened it, in order to get it in "RW" mode, which
the runtimes  prefer to  use.  Then it  would not  be possible  to abort
creation of the file by doing an abort close, since it has  already been
closed normally.

Note that  CLOSF always  sets bit '400 000 000 000  (do not  release the
jfn).  To release the jfn, you  can do a RLJFN after the CLOSF.   If the
extra argument is omitted, no bits other than '400 000 000 000 are set.

********************************  DELF  ******************************;

DELF  now  takes  an  extra  optional  argument,  DELF(chan,bits).  This
argument specifies bits to go in the left half of AC1 in the  DELF jsys.
The most useful  bit is '200 000 000 000.   Setting this bit  will cause
the file to be expunged as well as deleted.  Note that DELF  always sets
bit '400 000 000 000 (do not release the jfn).  To release the  jfn, you
can do a  RLJFN after the  DELF.  If the  extra argument is  omitted, no
bits other than '400 000 000 000 are set.

*******************************  IDTIM  ******************************;

IDTIM now  takes an extra  optional argument,  IDTIM(datime,bits).  This
argument specifies certain details  of the format expected by  the jsys.
The default value if this argument is omitted is 0.

******************************  OPENFILE  ****************************;

Openfile uses a somewhat  obscure algorithm to determine the  setting of
bit '400 000 000 000 in the GTJFN jsys.  This is the bit that determines
whether an existing version will be used if there is one, or whether the
next higher  version number will  be used.  If  you specify "O"  or "N",
this  bit  is  never  used,  since  it  is  meaningless  in  that  case.
Otherwise, the next higher version  is always used when "W" is  set, and
the highest existing version when "W" is not set.  (The one exception is
that  "W" with  "A"  will still  use  an existing  version,  for obvious
reasons.)  This causes problems for people who wish to open  an existing
file for "RW" access, since "RW" will cause the bit to be set that moves
one  to a  new version.   "ORW"  will cause  you to  update  an existing
version, but it will then give an error if there is no existing version.
In many cases you want to use the existing version if there is one, else
create a new file.  This  corresponds to setting no special bits  in the
GTJFN at all.

To  allow this  useful case,  we have  added an  option "U"  (Update) to
OPENFILE.   This is  like "RW",  except  that it  does not  set  the bit

causing the version number to  be advanced.  So it will use  an existing
version if there is one, else create a new file.

*******************************  RUNPRG  *****************************;

RUNPRG will now supply  a default extension if  you leave it out  in the
string.  This  is to allow  people to write  programs that will  work on
both Tenex and Tops-20 without changing the file name, since  the normal
extensions for executable files are different on these two systems.  The
default extension supplied will be .SAV for Tenex and .EXE for Tops-20.

                               SECTION  3

                          New Tops-10 Features

Current versions of SAIL  now support standard DEC Tops-10  systems more
fully than in the past.  Tops-10 is no longer treated as a poor relation
of Stanford  WAITS.  Descriptions  of the  features specific  to Tops-10

3.1 - SFD's

Any routine that  accepts a file  spec will allow  SFD's as part  of the
directory.  Note that CVFIL has a problem in this regard, as it tries to
return  the PPN  in a  reference integer  parameter.  If  the  file spec
includes SFD's, there is no obvious place to put them.  I have taken the
quick and dirty route of returning a pointer to the path block  in place
of a PPN.  This strategy  is reasonable because the monitor  will accept
such  a  pointer in  any  context where  it  wants a  PPN.   Because old
programs may  be expecting a  real PPN,  I do set  !SKIP! in  this case.
However I set  it to +1 for  SFD's, and -1 for  a real error.   Thus new
programs can be written to accept SFD's.

The project and  programmer numbers can be  omitted, as with  PIP.  Thus
[,,FOO] is the  SFD FOO in your  area.  [,] is your  area. But []  is 0,
i.e. your default path.

3.2 - Using SAIL from batch jobs

SAIL knows  whether your  job is  a batch job  or not.   (It looks  at a
GETTAB  bit set  up by  the batch  job controller.)   This  is desirable
because of SAIL's error handling.  It normally goes into  an interactive
error  handler  that  asks  the user  what  to  do.   This  is obviously
undesirable in a batch job, because the error handler is liable  to read
characters intended  as input or  commands.  Thus the  interactive error
handler is not called for  batch jobs.  In the compiler, SAIL  assumes a
line  feed  response  to  the  error  handler.   I.e.   the  compilation
continues.  This allows you to  see the maximum number of errors.   In a
user program, SAIL aborts the program on the first error.

3.3 - USETI and USETO

There  has been  a  problem previously  with  using USETI  and  USETO in
buffered I/O modes.  The problem is that the corresponding monitor calls
do not clear your I/O buffers.   Thus you can do a USETI, but  you won't
see  any data  from the  new block  until you  exhaust the  data  in you
current buffer ring.  (Of course there  is no easy way to know  how much

data you would  have to skip over.)   Similarly, after a  USETO, nothing
will  go out  to the  block  you specified  until the  current  block is
filled.  Under the new version  of SAIL, USETI and USETO both  clear the
buffer ring.  USETI clears the  input ring.  USETI and USETO  both force
out anything in the output ring that hasn't gone out yet, if  any.  Thus
the  next SAIL  I/O call  will use  the block  you specified.   Do USETI
before input and USETO before output.

Note that at Stanford the monitor clears the buffers as described above.
Thus this  change is  mostly simulating what  would happen  at Stanford.
However there output is only forced by a USETO.  Thus I am not  sure how
one  would switch  from output  to input  at Stanford.   Here  one would
simply do  USETI to  the desired block,  but at  Stanford that  will not

USETI -1 is a  special case.  It gets you  to the end of the  file under
TOPS-10.  (At Stanford  another method must be  used for this.)   If the
normal buffer clearing were done, USETI -1 would set your  EOF variable.
Since it is normally  used as a prelude to  output, you do not  want EOF
set, probably.   Thus USETI -1,  as a special  case, does not  clear the
buffer ring.

Mag tape positioning commands  (MTAPE) have a problem with  buffers that
is  exactly  the same  as  the problem  solved  by the  USETI  and USETO
patches.  Nothing has been done  about this, however.  Should you  be in
the middle of reading  a tape and do a  rewind, the next read  would get
the next buffer in  the ring, rather than  the first thing on  the tape.
This  can apparently  be  solved by  closing and  reopening  the device,
however, so it  did not seem to  be worth troubling about.   (That would
not work  for USETI and  USETO because closing  the disk also  loses the
file one is working with.)

3.4 - Changes to buffering

It was discovered that SAIL gave a different interpretation to  the byte
count in the routines intended for ASCII files (INPUT, OUT, NUMIN, etc.)
and those intended for binary files (WORDIN, ARRYIN, INOUT, etc.).  This
meant that  one could not  mix those routines.   E.g. one could  not use
both INPUT and WORDIN  for the same file.   Trying to do so  resulted in
losing characters from the file.  This problem has been fixed, so  it is
now  OK  to  use WORDIN  with  ASCII  files.  It  will  return  the next
character from the  file, as an integer.   Be warned that  under TOPS-20
WORDIN will always return the next 36 bits, even for ASCII files, so use
of WORDIN to  get a character will  make your program  incompatible with
TOPS-20 SAIL.  (There  is another function  under TOPS-20 to  return the
next character, however, so the incompatibility is not serious.)

3.5 - Non-blocking I/O

It  should now  be possible  to do  non-blocking I/O.  The  only problem
before  was  that you  couldn't  tell  when an  I/O  operation  had been
prematurely terminated  due to no  input being available.   The runtimes
would think  they had set  EOF, but input  failures in  non-blocking I/O
don't set any error bits.  Thus the runtimes carefully set EOF  to zero!
I have fixed the runtimes to guarantee that EOF will be non-zero when an
I/O function takes the error return.  If all of the error bits  are zero
(bits 760000), I  set bit 010000,  which previously the  runtimes always
cleared.  Thus bit 010000 will always be set for a non-blocking failure.
Probably this will be the only case when it is set, though  physical end
of tape may also do it.   Note that it is perfectly possible for  EOF to
be set in this way and for  you to still have valid data.  All  it means
is that the operation was terminated prematurely (before your  count was
exhausted) because an input failure occurred.  You should save  how much
you got and try to get the rest when the next input  available interrupt
comes along.

3.6 - TMPIN and TMPOUT

TMPIN now deletes  nulls and line numbers  from the tempcore  file being
read.  TMPOUT has been fixed so it no longer randomly sets bit 35 in the
words outputted.

3.7 - /A

The default value of /A is /0A.  This gives you the  linkage appropriate
for F40  for FORTRAN PROCEDURES,  and does  not use KI  or KL  op codes.
This  is  probably   wrong  for  most   places,  but  is   retained  for
compatibility with  the manual.   An individual user  can reset  this by
specifying /nA  in a  REQUIRE COMPILER!SWITCHES  statement.  A  site can
change  the  default  by  patching the  compiler.   To  do  this without
recompiling, just look  at XINI4+7.  You  will find MOVEI  TEMP,0; MOVEM
TEMP,ASWITCH.  You can change the MOVEI TEMP,0 to use whatever value you
want as default.  To change this in the source, see the file SAIL.

Users should consider  setting /26A.  In  addition to F10  linkage, this
causes KI-10 instructions to be used for converting between  integer and
real numbers.  However it causes rounding to be used, while  the default
is trucation (FLOOR).

3.8 - COMPIL

We are supplying a .COR file for COMPIL, to improve the handling of SAIL
by  COMPILE-class commands.   The following  assumes that  these changes
have been made.

*******************************  /BAIL  ******************************;

You may use the  switch /BAIL:nn  It will  pass /nnB to the  compiler in
the appropriate  place.  It will  also cause COMPIL  to look for  a .SM1
file rather than a .REL  file.  Thus your program will be  recompiled if
it had not originally been compiled with BAIL.  If you use  /BAIL alone,
i.e. without an argument, /BAIL:17 will be assumed.

*******************************  DEBUG  ******************************;

The DEBUG command  now uses BAIL as  its debugger by default.   You need
not have any declarations or  calls for BAIL in your program.   My magic
linkage will automatically put a call to BAIL in your program before the
first executable instruction.  When you get in this BAIL  breakpoint you
can then set any other breakpoints you want.  That breakpoint that I set
up is immediately removed, by the way.  DEBUG forces /BAIL:17,  which in
turn  forces  recompilation  if your  program  had  not  originally been
compiled with /BAIL.   To debug with  DDT, specify DEBUG/DDT.  Note that
the linkage to  BAIL used by DEBUG  causes the descriptors to  be loaded
for all SAIL runtimes.  Thus it  simulates the 20 bit in the  /B switch.
However, these  descriptors are  loaded only when  the DEBUG  command is
used, whereas /20b would have them in your core image even during normal
executions.  Thus our implementation saves some core.

*********************************  /Y  *******************************;

Using /Y  will cause your  program to be  loaded with the  SAIL sharable
high segment  (SAISG8).  Note that  /Y must appear  before or  after the
first program name in the command.  Any later and it will not  work.  /Y
may be used with DEBUG as  well as LOAD and EXECUTE.  (It has  no effect
for COMPILE, of course.)

                               SECTION  4

                          Documentation Errors

This is a list of known bugs in the August 1976 Sail manual, AIM-289.

PAGE                    DESCRIPTION
abstr.  "varaiables" is a misspelling   [JFR 10-22-76]

iiiL    no period after LEAP (line 6 of paragraph)      [LES 10-22-76]

162L    "i.e" in the line "2. Recursive entry"  [JFR 10-23-76]

1R      "Nauer" for "Naur" (also References)    [JFR 11-2-76]

22L,26L "disjunct" -> "conjunct"                [JMC 11-12-76]

31L     line -9 "its" -> "it's"                 [JMC 11-12-76]

162R    The word PDA+'13 contains something other than indicated.
        The parameter descriptor words actually start at PDA+'14,
        but the way to find them is to follow the pointer in
        the right half of PDA+7.                [JFR 12-9-76]

9L      Another restriction on SIMPLE procedures: They should not do
        up-level addressing themselves (in addition to point 4.) unless
        the user really understands what is going on with the stack.
        It is possible to "screw up" without complaints from the
        compiler. SIMPLE ought to mean "I know what I am doing, so let
        me do it.". [JFR/DON 12-xx-76]

56L     CRLF="('15 & '12)", not '12 & '15       [JFR 1-15-77]

10R     It should be made clear that  LET A=B;  works even if
        A is a reserved word.  In particular, LET DEFINE=REDEFINE;
        Also note that B can be any reserved
        word except COMMENT. [COMMENT ALWAYS means "ignore through
        the next semicolon".]

4R      POLLING!POINTS is not a valid <require!spec>    [WFW 1-21-77]

50R     In FILEINFO, hidate2 occupies 3 bits    [JFR 2-3-77]

152L    CHNCDB and FILEINFO are defined everywhere except TENEX.
        [JFR 2-3-77]

65R     A better way of getting around the array problem is as follows:

        REQUIRE "<><>" DELIMITERS;

        DEFINE NewArray(type,name,bounds)=<
                type ARRAY proxy bounds;
                MEMORY[LOCATION(name)] _ MEMORY[LOCATION(proxy)];
                MEMORY[LOCATION(proxy)] _ 0;

        which hides all the hair of a poor facility and is perfectly
        general. unlike the present scheme in the manual. A typical
        call would be:

        RECORD!POINTER (RC) rp;

        rp _ NEW!RECORD(RC);
        NewArray(STRING,RC:SA[rp],[0:1,-2:3]); [MWK for KS 01-13-77]

27L     DIV and MOD use integer divide and are meant as a "integer
        divide" and "integer divide and remainder". This is NOT the
        real mod as written in Knuth volume 1. In fact, MOD would
        better have been named REM. [MWK 01-13-77]