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Trailing-Edge - PDP-10 Archives - tops10and20_integ_tools_v9_3-aug-86 - tools/casestdy/case3ici.mem
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               T H E    C O N V E R S I O N     O F     P M S



                        A    C A S E     S T U D Y



























       Trevor Moore                                           Chris Bond
       John Morris                                           Jacky Quinn

       ICI Petrochemicals Division           Large Systems Skills Centre
       Wilton                                                  DEC Leeds
       Cleveland                                               Yorkshire
       ENGLAND                                                   ENGLAND

















                                    
                                    ABSTRACT

            +--------------------------------------------------------+
            !                                                        !
            !   This paper  describes  the  conversion of a  large   !
            !   production data base  and program from a  DEC 2060   !
            !   to a VAX 780.  The data base is a DBMS20 data base   !
            !   and the program is written in  COBOL using TRAFFIC   !
            !   for its screen handling.     The converted product   !
            !   uses DBMS32, COBOL and TDMS.                         !
            !                                                        !
            !   The paper concludes that in this instance the con-   !
            !   version was achieved with relative ease.  The pen-   !
            !   ultimate section makes some suggestions about  how   !
            !   future integration requirements might be met while   !
            !   the final section draws some general conclusions.    !
            !                                                        !
            +--------------------------------------------------------+
                                                           Page 1


     1.0  INTRODUCTION

          This PAPER describes the  process  of  taking  a  large
     program  suite  written to run under TOPS20 on a DEC2060 and
     converting it to run under VMS on  a  VAX780.   Because  the
     program  uses  DBMS20  this  conversion  also  involved  the
     transfer of the whole database structure  and  most  of  the
     data  for  the  DEC20  to the VAX.  Because it describes the
     conversion of one specific program to do a specific job this
     note  should  not  necessarily  be  taken  as describing the
     process by which other  conversion  exercises  are  tackled;
     rather  it  is  a  case  study  and as such will provide the
     reader with guidelines should he wish to  tackle  a  similar
     exercise.    The   main  body  of  the  note  describes  the
     conversion in general terms;  specific  and  more  technical
     examples  refered  to  in  the  main  body  of  the text are
     included as appendices.

          The reader is assumed to have a  working  knowledge  of
     TOPS20, COBOL-20, DBMS20 and TRAFFIC20 but is not assumed to
     have  more  than  a  passing  acquaintance  with   the   VAX
     equivalents.



     2.0  OBJECTIVES OF EXERCISE

          The objective of the exercise  was  to  do  a  straight
     conversion  from  the  one  system to the other.  This means
     that no redesign was to be done (in fact some was  done  for
     reasons  which  will be explained) and that existing bugs on
     the 20 version would not be deliberately  fixed  (indeed  in
     porting  the  software  we  did  actually  port  the bugs as
     well!).  One corollary of this is that no attempt  has  been
     made to tune the converted product;  the database design for
     example more or less reflects the strucure on the DEC20.



     3.0  BACKGROUND

          ICI is one of the largest  chemical  companies  in  the
     world.   Petrochemicals  and Plastics Division is one of its
     divisions;   the  Division  employs   15000   people.    The
     Division's   major   manufacturing  base  is  at  Wilton  in
     Cleveland, England and comprises a number  of  very  capital
     intensive  continuous  process  chemical  plants.   Chemical
     plants cost a lot to run and in order to improve efficiency,
     productivity,  energy  consumption  etc operating parameters
     are continually monitored.  Critical parameters are measured
     in  real  time  by  a  wide variety of machines (mainly DEC)
     including 2 VAX780s.  The Production Management System (PMS)
     is  designed  to store and allow the rapid retrieval of data
     associated with the operation of the chemical  plants.   The
     system  runs  on  a 2060 and collects its data from the real
                                                           Page 2


     time  machines,  from  manual   input   and   from   regular
     calculations.   Data  can  be retrieved either directly from
     the data base or can be transferred - using Robins  (VT180s)
     and  a  COBOL-callable KERMIT - to floppy disks and examined
     using CP/M software.

          The program suite which was converted is called  PLNTIN
     and  is the major input facility in PMS.  It is also the one
     which has absorbed  the  most  effort  both  in  design  and
     performance  terms.   Appendix  A  describes  in outline the
     function of the program and the design  of  the  data  base.
     Appendix  B describes the structure of the program suite and
     its component modules and describes  the  functions  of  the
     major modules.



     4.0  ORIGINS OF EXERCISE

          In mid-1983 ICI began to evaluate  its  options  for  a
     continuing  computing  strategy.   ICI recognised that there
     were three distinct types of production system:

          1.  Established systems

              ICI has many systems which are in  maintenance
              mode  running  on  2060's.   These systems can
              satisfactorily remain  where  they  are  since
              hardware and software support for the KL is to
              continue.

          2.  New systems

              ICI felt that new systems  with  a  long  life
              expectancy  could  not  reasonably be put on a
              machine whose  future  was  obviously  finite.
              They  would  be  designed  and  implemented on
              other hardware - possibly the VAX.

          3.  Developing systems

              These systems were the problem.  Clearly there
              was little point in continuing to develop long
              term a system which was 40 man  years  into  a
              100 man year development cycle.


          It was in addressing the developing  systems  that  the
     conversion  feasibility  study emerged.  One of the problems
     that ICI was worried about  was  the  amount  of  retraining
     which  might  be necessary both for programmers and analysts
     and also - most importantly - for users.  ICI wanted ideally
     to  have  a  system  on  the  VAX which was identical to the
     system on the 20 in every respect.  In fact  the  conversion
     came very close to achieving that ideal and without too much
                                                           Page 3


     difficulty.



     5.0  EARLY CONSIDERATIONS

          Early on in the process - before Digital was involved -
     ICI identified 6 areas of concern

          1.  Languages

              PLNTIN is written in COBOL Version 12b.  Since
              ANSI  standards  for  COBOL are fairly rigidly
              enforced few  if  any  compatibility  problems
              were  envisaged  in this area.  (COBOL Version
              13 will provide the programming  constructs  -
              such  as  in-line  PERFORMS, END-IF etc - that
              are missing from Version 12b  but  present  in
              VAX COBOL.)

          2.  Databases and Files

              ICI quickly discovered  that  although  DBMS32
              was  a  CODASYL database it was different from
              DBMS20.   At   the   programmer   level   some
              retraining  would  be  necessary.   It was not
              felt that sequential and relative files  would
              present  a  problem.   PMS  does  not use ISAM
              files.

          3.  Screens

              This  was  rapidly  identified  as  being  the
              potential  trouble spot.  Screen handling uses
              TRAFFIC Version 4.0.  This  is  different  and
              more   powerful  in  some  important  respects
              (notably  data  input  validation)  than  TDMS
              (and, in fact, than TRAFFIC version 2.0).  The
              decision was made to use TDMS as this  follows
              Digital's     mainstream     screen    product
              development direction.   It  might  have  been
              easier to use FMS but in fact TDMS can be made
              to emulate TRAFFIC and FMS.

          4.  IPCF  -  Interprocess  Communication  Facility
              (IP20)

              Much communication between processes  is  done
              by  sharing  memory and due to virtual address
              space restrictions on the 2060  (we  only  use
              section  0 of course) considerable use is made
              of IPRUNI (ie CFORK%, SFRKV% and WFORK%).   It
              was  quickly  demonstrated  that VMS mailboxes
              handle   this   aspect   nicely    and    that
              subprocesses can be spawned on the VAX.
                                                           Page 4


          5.  Assembler

              ICI has many  assembler  routines  written  in
              MACRO36  but  fortunately these are all small.
              In general these  routines  just  implement  a
              couple  of  JSYSes  or  activate the interrupt
              system.  As it happened  all  these  could  be
              handled by VMS system services called directly
              from COBOL.  In fact since the conversion  ICI
              has   worked  on  converting  its  only  large
              MACRO36  program  to  MACRO32   and   'C'   in
              parallel.   While  the  conversion  to  'C' is
              relatively straightforward (although  actually
              a  rewrite)  the  conversion to MACRO32 is not
              difficult;  for instance  JSYS  calls  can  be
              replaced  by subroutines, SETZM by CLRL and so
              on.

          6.  Operating System

              ICI felt there are some mainly operational and
              administrative    shortcomings    within   VMS
              compared with TOPS20.  For example queuing  of
              mount  requests,  archiving  and retrieval are
              things which one might expect  to  find  in  a
              large time-sharing operating system.  However,
              consideration is being given to the  inclusion
              of   these  and  other  facilities  in  future
              versions of VMS.


          These considerations - together with the  formation  of
     Digital's  UK Large Systems Skills Centre at Leeds (70 miles
     away from ICI Wilton) - led rapidly to a team being  set  up
     to do the conversion.



     6.0  METHOD OF APPROACH

          The method of approach was to tackle the conversion  in
     two separate but overlapping stages.

     Stage I  - To convert and implement the data-base structure on the VAX
                and to transfer data out of the 20 data base and into the 
                VAX data base.

     Stage II - To convert, compile and test the programs on the VAX.
                                                           Page 5


     7.0  CONVERSION OF THE DATA BASE

          As it turned  out  conversion  of  the  data  base  was
     accomplished   with   relative   ease.   There  are  several
     conceptual differences between DBMS32 and DBMS20.   Specific
     examples   include  the  different  implementation  of  CALC
     records.  On the VAX every CALC record must be the member of
     a set whose owner is the SYSTEM record.  The VAX maintains a
     system record on every page of the physical data  base.   In
     this  sense  the  SYSTEM  record  behaves  like a CALC CHAIN
     HEADER in DBMS20.  Another  example  is  that  there  is  no
     concept  of  a  REALM in DBMS20.  In designing the data base
     for the 2060 ICI had taken full advantage  of  the  physical
     record  placement  clauses allowable in the DDL description.
     These cannot  be  completely  mirrored  in  DBMS32  although
     shadow  clustering  allows some physical design flexibility.
     These differences (and this is not an exhaustive  list)  had
     to be learnt by the ICI people.

          The next stage was to redesign the data base in  DBMS32
     terms.   This  was done with DEC Valbonne confirming the ICI
     suggestions.  The result was a converted  data  base  schema
     description  which  at  this stage was in source form on the
     2060.  (It is worth saying that in the early stages  of  the
     exercise  all source was written on the 2060 and compiled on
     the VAX!!) The schema was moved to the VAX by tape transfer.
     Initially CHANGE was used but this resulted in difficulties.
     We actually ended up using the  method  recommended  in  the
     TOPS20  manuals (see Tape Processing Manual ref AA-H180A-TM,
     Chapter 6).  Appendices C and D describe this method in more
     detail than the manual.

          The standard PMS unload program was modified  to  allow
     data  to  be  unloaded  in  ASCII  form  eg COMP fields were
     unloaded as DISPLAY and a VAX reload program was written  to
     load  the  data  into the VAX.  Again data was transfered by
     tape.  As it happened the loading of the data  base  on  the
     VAX  worked first time!  The only difficulty we did have was
     that the VAX is  more  stringent  in  its  data  conversion,
     typing and checking than the 2060.  For example it would get
     upset by embedded nulls in packed decimal fields.

          Writing the unload programs brought out the differences
     in  DML between DBMS20 and DBMS32.  These are few;  the main
     ones are  the  different  way  in  which  a  transaction  is
     delimited  and the way in which currency is handled.  Record
     currency was the  main  area  of  difficulty  in  converting
     PLNTIN  itself.   The action of KEEPLISTs in DBMS32 does not
     mirror exactly the action and effect of the MOVE STATUS  DML
     command  in DBMS20.  The VAX COBOL COMMIT statement releases
     currency under version 2.  (Under version 3 COMMIT RETAINING
     [currency]  is implemented but this may affect lock status.)
     Appendix  E  lists  one  or  two  of  these  examples  in  a
     comparitive way.
                                                           Page 6


          At this stage the importance of  DBQ  became  apparent.
     Although  we  had  no  programs we could still look at - and
     modify - the data in the data base.  There is  no  supported
     utility  equivalent  to DBQ on the 2060.  There is a utility
     called XDML which does what  DBQ  does  which  ought  to  be
     released  as DBQ20.  This, of course, supports recognition -
     including recognition on data names!!  This would have  been
     useful   in   this   exercise   as   one   record   name   -
     OPERATIONAL-BDY-RECORD  -  is  unique  in  the   first   two
     characters!!   We  now understand that XDML is to be bundled
     with version 6.1 of DBMS20.

          The exercise to this stage was  very  much  a  learning
     exercise.   It  was  also  one  off;   once  the  data  base
     conversion is done and the lessons learned there is no  need
     to go through it again.



     8.0  CONVERSION OF THE PROGRAMS

          We split the various modules which comprise  PLNTIN  up
     into 3 categories as follows:

          1.  modules which do not use DBMS and do no screen i/o

          2.  modules which do use DBMS but do no screen i/o

          3.  modules which do use DBMS and do screen i/o


          The first step we took to convert COBOL code was to run
     a  raw  COBOL20  program  of  category 1 above (ie no DML or
     screen calls) through the VAX COBOL compiler.  This  pointed
     up  basic  syntactic differences such as VAX COBOL's dislike
     of ID for IDENTIFICATION.  In addition to the information we
     got from this we had gathered much information from the data
     base conversion.  At about this time a  Digital  integration
     document was issued which listed differences between the two
     COBOLs.   A  selection  of  the  differences  we  found   is
     contained in Appendix F.

          For the next stage we set as a target  the  achievement
     of  a  clean compilation of everything.  This we achieved by
     the rote replacement of syntactic differences  the  one  for
     the  other.   This  is  probably  not the way one would do a
     conversion in practice - more thought is  advisable.   Calls
     to  assembler routines - like TRAFFIC calls - were commented
     out.  We very  quickly  ended  up  with  a  set  of  cleanly
     compilable   programs  most  of  which  were  non-functional
     because we had done nothing about screen i-o.

          One point worth making here  is  that  we  had  been  a
     little  worried  about the effect of the different word size
     on the two machines.  In this particular exercise we had two
                                                           Page 7


     reasons  for  concern (neither of which were justified as it
     happened).  First much use had been made of  the  fact  that
     PIC  9(10)  COMP  fits  into  36  bits.  So on the 2060 many
     numeric codes were based on, say, the concatenation of two 5
     digit  numbers.   We  had to convert to DISPLAY to get round
     this (you can only get PIC 9(9) COMP into  a  32-bit  word!)
     which  uses  more  space  on  disk  (and  insignificantly in
     memory) but which doesn't cause  any  technical  difficulty.
     Since  data  type  conversion  is  all microcoded on the VAX
     there may not be any significant performance  penalty.   The
     second area of concern was that PLNTIN actually set the bits
     in a word and used the bits as flags.   To  set  bit  0  the
     program  would add 1 to a variable to set bit 4 it would add
     16 and so on.  In fact this rather primitive idea  converted
     as it stood to the VAX.

          On reflection,a number of  lessons  were  learned  from
     this  process.   The quality of the code being converted was
     variable and we found that well structured code  was  easier
     to  convert than poorly structured code.  Poorly written and
     poorly structured code is more  difficult  to  convert  than
     good   code.   This  is  particularly  true  in  the  screen
     conversion area where some restructuring may be necessary.

          The  act  of  conversion  does,  however,  present   an
     opportunity  to look at program structure and content.  When
     converting it is important to examine  the  code.   This  is
     partly  to  gain  some  insight  into  the  way the original
     programmer  worked  and  thought  but  also  to  assess  any
     potential difficulty.  Code with neither screen or data base
     calls presents little or no difficulty.  Code with only  DML
     -  and  no  screen  calls  -  becomes straightforward once a
     standard error handling procedure is decided.

          It is possible to break the screen conversion procedure
     down.   When  examining  the  nature  of  the  screens it is
     important to consider:

          1.  how much input and output of fields is required

          2.  whether the forms access more than one record

          3.  what use is made of special function keys

          4.  how much and what sort of help is  presently  given
              at run-time
                                                           Page 8


     9.0  SCREEN CONVERSION

          As remarked above we had anticpated  that  the  screens
     would cause us the most trouble.  They did;  but not as much
     as we had feared.

          PLNTIN  uses   TRAFFIC20   (the   new   version   4.0).
     Unfortunately  it does no TRAFFIC section reads but gets all
     its data by reading a field at a time.  On the  face  of  it
     replacing  a  section  read  in TRAFFIC by a request in TDMS
     would have worked.  But the way PLNTIN is  written  it  gets
     information a field at a time.  So for example consider this
     screen:


                     +---------------------------------------+
                     !                                       !
                     !             SAMPLE SCREEN             !
                     !                                       !
                     !            Enter name: ______         !
                     !             Enter age: ___            !
                     !  Enter marital status: _              !
                     !                                       !
                     !                    OK? _              !
                     !                                       !
                     +---------------------------------------+



          TRAFFIC would enable you to set this up  as  a  section
     and  read  it  in one fell swoop (go).  TDMS works like that
     and such a use of TRAFFIC might  have  made  the  conversion
     easier.   Unfortunately  PLNTIN  would  read the screen like
     this:


                               Paint screen

             +->  not  +-----> Read name
             !    OK   +-----  Validate name   ---------+
             !                                          !
             !    not  +-----> Read age                 !
        try  !    OK   +-----  Validate age    ---------+
             !                                          !     allow panic
       again !    not  +-----> Read status              !---->exit on
             !    OK   +-----  Validate status ---------+     <UPARROW>
             !                                          !
             !    not  +-----> Read OK                  !
             !    OK   +-----  Validate OK     ---------+
             !
             +---------------  Act on OK
                                   !
                                   !
                                   V
                               continue
                                                           Page 9





          where the read statements were not  contiguous  in  the
     soure file.  TDMS would want to say:

                   not  +----->  Do request
                   OK   +-----   Validate data


          There are a number of problems here.  TRAFFIC version 4
     allows  the  inclusion  of  field validation (vet) routines.
     These are like the User Action Routines available in FMS and
     allow  validation  of the input to a field at the time it is
     input.  So, for example, as soon as the  name  is  read  the
     data  base can be checked for existence and the field reread
     as necessary.  ICI feel that TDMS would be a  much  stronger
     product  if  it  had  the  ability  to  perform user-defined
     field-level  validation  checks.   Since  TRAFFIC  validates
     field  by  field,  the  user  gets feedback (when necessary)
     immediately he has completed a field.  With a  TDMS  request
     he  must  type in the whole screen (request).  This can mean
     that he types a lot of data in that he would not have  typed
     in had he had a response earlier.

          This would not have met our  criterion  of  having  the
     converted  product  look  and  feel  like the original.  The
     obvious way round this is to generate  a  request  for  each
     field read.  Since requests are stored in a run-time library
     we thought that there would  be  a  significant  performance
     penalty  in doing this.  As it happens TDMS has the facility
     of acting on data items  that  it  calls  'control  fields'.
     These  enable  a  single  request  to  do  different  things
     according to how the control field is set at the outset.  We
     mapped  the  TRAFFIC  section  numbers  onto a control field
     which caused  the  TDMS  request  to  mimic  the  action  of
     TRAFFIC.   Appendix  H  describes in detail how this is done
     and gives coding examples.

          This  method,  although  an  elegant  solution  to  the
     problem  of  a  rapid  conversion,  is  still not as runtime
     efficient as using TDMS as it was designed to be used.  This
     solution was applied to the INPUTR module which is where the
     data is actually input.  The PLNTIN module  was  tackled  by
     using  TDMS  as  it  was designed to be used.  This actually
     resulted in some  fairly  difficult  restructuring  but  the
     result  was screens which painted more smoothly.  Appendix G
     describes the different approaches in more detail.
                                                          Page 10


     10.0  TESTING THE PROGRAMS

          Testing the programs fell into two stages:  testing the
     screen flow and testing the data updates.

          Screen flow testing (ie testing the superficial program
     flow  logic)  was  done  as  the  screens  and requests were
     developed.  This proved to be relatively time  consuming  if
     not  particularly  difficult.   The  major difficulty was in
     understanding the original code rather than in  implementing
     it.   An  example  of  the sort of problem at this stage was
     where a field was not rewritten in reverse video when it had
     failed validation.

          We had to give some thought  to  the  use  of  function
     keys.   TRAFFIC  allows  the  programmer  to  pick  up,  for
     example, the arrow keys.  TDMS does not recognise arrow keys
     but  uses  the GOLD (PF1) key followed by another key.  This
     is the only significant  difference  between  the  converted
     program and the original product .  As an example, GOLD-X on
     the VAX replaces UP-ARROW on the 2060 as the  program  abort
     key.   Appendix I describes the use of special function keys
     in more detail.

          Testing that  data  base  updates  have  been  properly
     processed  is  most  important.   By  and large because this
     involved no restructuring  of  code  the  conversion  worked
     first time.  It turned out that the one or two bugs we found
     here were present on the 2060 version.  But here  again  DBQ
     proved an invaluable aid.



     11.0  ASSEMBLER ROUTINES

          All assembler routines  were  replaced  by  VMS  System
     Services  which  means that the VAX version uses no assembly
     level code.  In particular a MACRO20 routine to submit a job
     to  the  batch  queue  is replaced by a call to LIB$SPAWN to
     execute a DCL command which submits  the  job.   Appendix  J
     gives one or two examples.



     12.0  REFLECTIONS

          At the end of the conversion exercise ICI were relieved
     to  discover  that  it  had  been less painful than they had
     anticipated.  But there are a number of comments  one  might
     make  both  in  terms  of establishing forward compatibility
     standards and in terms of tools and  utilities  which  might
     help  the  movement  of data and programs between the 20 and
     the VAX.
                                                          Page 11


          1.  VMS  help  is  very  good  but  it  involves   more
              keystrokes  than the 20.  The in-line help facility
              ('?')was sorely missed.

          2.  TDMS would be stronger if user-defined, field-level
              could  be set up.  Form definition and modification
              within TDMS is easier than within TRAFFIC.

          3.  VMS needs some convenient - and supported - way  of
              handling   standard  administrative  and  operating
              tasks such as  tape  and  disk  mounts,  archiving,
              retrieval etc.

          4.  XDML should be finished and released  as  DBQ20  as
              soon as practicable.

          5.  In the light of the recent release  of  the  DBMS32
              load/unload  facility,  a  useful  tool would be an
              unload program on  the  20  which  would  unload  a
              DBMS20 data base into a format suitable for the VAX
              load program.

          6.  The ability to set breakpoints  in  the  VAX  COBOL
              source  debugger  at  lines is a significant aid to
              debugging.  The same feature in the 20  COBOL  (and
              other) debuggers should be incorporated.




     13.0  CONCLUSIONS


          1.  The  conversion  used  no  assembler.    This   was
              important to ICI who have no systems programmers as
              such.

          2.  It is possible to mimic TRAFFIC with TDMS.

          3.  The COBOL and DBMS software is sufficiently similar
              to make conversion fairly straightforward.

          4.  An exercise like this gives an opportunity  to  ask
              anew  questions about program structure, design and
              content.

          5.  At the outset  ICI  thought  they  would  not  miss
              recognition - they did!

          6.  Quality of code is important.

          7.  The second method of screen conversion was  quicker
              and more simple to implement.  (See Appendix G.)
                                                          Page 12


          8.  VMS is a good operating system to work with;  it is
              just different from TOPS20.

          9.  But the bottom line is that the  conversion  worked
              and it worked well.











                              APPENDIX A

             FUNCTION OF PMS DATA BASE AND PLNTIN PROGRAM



          PMS is the Production Management System.  It is used to
     monitor  the  performance  and  operation  of large chemical
     plants.  PLNTIN is possibly the most important  of  all  the
     PMS  programs.   It  is by using this (or one of a number of
     flavours of the same thing) that PMS collects  most  of  its
     data.   The other method of data collection is via a link to
     two PDP-11's which get information from the data loggers and
     real-time VAX780's on the plants.

          At  its  heart  the  data   structures   of   PMS   are
     straightforward.   It  is  only  the detail which clouds the
     issue.  A chemical manufacturing complex  (called  a  WORKS)
     can  be  considered  as  a  hierarchy of smaller components.
     These components are known as OPERATIONAL  BOUNDARIES  (more
     usually  OB's).   The hierarchy of OB's is refered to as the
     BOOB (Bill Of Operational Boundaries).  An OB may be a whole
     plant  or  it may be a single pump.  But in general an OB is
     composed of a number of smaller OB's.  For example the NYLON
     OB  has  component  OB's  called  SOLVENTS  and ACIDS (among
     others).  At the bottom of the heap are some 'element'  OB's
     which   have   no   components.    These   have  no  special
     significance.

          The most important attribute an OB may possess is  that
     it  may  have associated with it a number (possibly zero) of
     MEASUREMENTS.  A measurement  is  something  that  can  have
     associated with it a time series of VALUES or READINGS.  The
     terms 'VALUE' and 'READING' are used interchangeably.

          So for example the SOLVENTS OB  has  some  measurements
     called, say, YIELD and MAKE.  Each of these measurements has
     a value for a series of times - there is a January  YIELD  a
     February YIELD and so on.

          Values can be of one of two types - CALCULATED or  RAW.
     Raw  data is read by PLNTIN (or one of its flavours) or read
     from a data logger.  Calculated  values  are  calculated  by
     CALCNS.
     FUNCTION OF PMS DATA BASE AND PLNTIN PROGRAM        Page A-2


          The reading of certain raw data  is  the  objective  of
     PLNTIN.   PLNTIN  needs  to  know  for which measurements it
     needs to get  values.   There  are  LISTS  of  measurements.
     Everyone who uses PMS is registered within the data base and
     some users may have INPUT LISTS.  An INPUT LIST is a set  of
     measurements  which  is  to  be  read.  An input list may be
     SCHEDULED - in which case there is a specific time at  which
     it  must  be  read  -  or  UNSCHEDULED - in which case there
     isn't.

          In CODASYL network data base terms because one LIST can
     have  many MEASUREMENTS and one MEASUREMENT could be on many
     LISTS we need a  link  record.   This  record  is  called  a
     MEASUREMENT  LIST  ENTRY  (MLE or more affectionately Emily)
     and is central to the PMS data base.  There are also  OUTPUT
     LISTs  but  these  are  used  by  other  reporting programs.
     Figure 1 below describes a much simplified view of the  data
     base structure.



            +---------+        +---------+                   +---------+
            | OB      |------->| BOOB    |                   | USER    |
            |         |------->| LINK    |                   |         |
            +----+----+        +---------+                   +----+----+
                 !                                                !
                 !                                                !
            +----V----+                                      +----V----+
            | MEAS    |                                      | LIST    |
            |         |                                      |         |
            +--+---+--+                                      +----+----+
               !   !                                              !
               !   !                                              !
               !   !                                              !
               !   !                   +---------+                !
               !   +------------------>|  MLE    |<---------------+
               !                       |         |
               !                       +---------+
          +---------+
          | READING |
          |         |
          +---------+


                               Figure 1



          Every reading (raw or  calculated)  must  be  validated
     before  it  is  stored on the data base.  The results of the
     validation tests are  stored  in  a  coded  fashion  in  the
     READING-RECORD  for  the reading concerned.  The tests which
     are to be carried out on a reading  are  attributes  of  the
     measurement.   So for each measurement there is a collection
     of validation tests.  These are stored as a set  of  records
     FUNCTION OF PMS DATA BASE AND PLNTIN PROGRAM        Page A-3


     owned  by  the  measurement record.  They are duplicated for
     reasons of performance in the MLE record.  Validation can be
     straightforward  -  such  as maximum and minimum checks - or
     more complex -  such  as  trend  checking.   The  validation
     program  -  VALTWO  -  is a fairly large and complex program
     which reflects the nature of the validation that is  carried
     out at data input time.

          There is also a set of COMMENT-RECORDs (possibly empty)
     owned by a reading record.

          Finally there are a couple of records designed to  keep
     track of amendments to values.  PLNTIN can be used to change
     values  which  have  been  entered   (subject   to   certain
     restrictions).   If  this  is  done  the  old  value and any
     comments are moved to two other records.











                              APPENDIX B

                         COMPONENTS OF PLNTIN



     B.1  OUTLINE OF STRUCTURE OF PLNTIN

          PLNTIN is composed of a number of modules as follows:


               +---------+                                Response to TTY of
               |PLNTIN   |                                requestor (TERTLK)
               |         |                                        ^
               +----+----+   (call to SUBMIT)                     !
                    !---------------------------------+           !
                    !                                 !           !
               +----+----+                    +-------+--------+  !
               |INPUTR   |                    |Batch .CTL file |  !
               |         |                    |----------------|  !
               +----+----+                    | MMDATR         |  !
           _________!_________                |  (*.RCD,*.DAT) |  !
          !                   !               | EXPTER         |  !
          !                   !               |  (IPRUNI'd from|  !
     +----+----+         +----+----+          |     MMDATR)    |  !
     |ICOMNT   |         |PLTSHF   |          |                |  !
     |         |         |         |          |                |  !
     +---------+         +---------+          |        !       |--+
                                              |        !       |
                                              +--------!-------+
                                                       !
                                                       !
                                                       V
                                            SUBMIT to PRINT/DELETE
                                            *.HLD of errors to LPT







     Each of the modules on the left  side  of  this  figure  are
     composed of further submodules.  The conversion exercise did
     not  tackle  the  ICOMNT  and  PLTSHF  modules.   PLTSHF  is
     essentially  a  callable  version  of  another  PMS program.
     COMPONENTS OF PLNTIN                                Page B-2


     ICOMNT is used to put comments into the data base.



     B.2  OUTLINE OF FUNCTIONS OF MAJOR MODULES

          B.2.1  PLNTIN


               1.  determines which is the next list to be input.
                   It  may  be  passed  this  by a top level menu
                   program through the  TOPS20  process  argument
                   block.  If the user has not specified the list
                   at the higher level then PLNTIN checks to  see
                   if  the  user has scheduled lists.  If he does
                   then PLNTIN works out which is the  next  list
                   that  should  be input.  The user may select a
                   list whose values have already been entered in
                   which case PLNTIN goes into amend mode.

               2.  gets the information  about  the  measurements
                   associated  with  this list and puts them in a
                   big array.  If the values are already  entered
                   they are put in the array as well.

               3.  PLNTIN calls INPUTR passing the big array

               4.  when INPUTR is finished PLNTIN  sets  off  the
                   batch   job  to  run  MMDATR  and  immediately
                   returns control to the higher level




          B.2.2  INPUTR


               1.  displays the data received in the big array on
                   the screen

               2.  reads data from each  field  validating  input
                   using  VALTWO as it is input.  Also allows the
                   user to get more validation information and to
                   run PLTSHF (qv)

               3.  allows the user to input  comments  associated
                   with  any  number  of readings (call to ICOMNT
                   (qv))

               4.  reading values are written  to  a  *.DAT  file
                   which  is  read  by  MMDATR (qv) to update the
                   data base
     COMPONENTS OF PLNTIN                                Page B-3


               5.  returns control to PLNTIN when user wishes  to
                   process data




          B.2.3  ICOMNT


               1.  accepts the user comment via EDITPM and allows
                   this  comment  to  be copied to apply to other
                   entries

               2.  comments are written to a *.RCD file.  This is
                   used by MMDATR (qv) to update the data base

               3.  returns control to INPUTR




          B.2.4  PLTSHF


               1.  lets the user  view  up  to  the  previous  50
                   values of a given measurement

               2.  returns control to INPUTR

                      Note: MMDATR is run as a batch job so that the user may
                            continue  using PMS while the data  base is being
                            updated. MMDATR may take several minutes to run.





          B.2.5  MMDATR


               1.  actually updates the data base using
                        (a) *.DAT which holds the  data  for  the
                   while transaction
                        (b) *.RCD which holds  comments  for  the
                   readings
                   The value of * is determined by  the  time  at
                   which the files are created so these files are
                   unique.  They are deleted at the  end  of  the
                   run.

               2.  IPRUNI's EXPTER which updates the history data
                   base.   EXPTER only runs if there is exception
                   information from the user's input.   If  there
                   is  then  EXPTER  runs RUNPRT to print out any
                   processing   error   information.    Otherwise
     COMPONENTS OF PLNTIN                                Page B-4


                   RUNPRT is run by MMDATR.

               3.  sends a message to the TTY which requested the
                   job  (via  TERTLK)  saying  that  the  run has
                   completed ok or not

               4.  sends  a  message  to  WAYTER  reporting   its
                   completion.  (WAYTER collects information from
                   different runs of PLNTIN during  a  shift  and
                   then  runs the calculation program CALCNS when
                   all the information is in.)

               5.  tidies up and exits











                              APPENDIX C

                 TRANSFER OF FILES FROM DEC20 TO VAX



     C.1  TRANSFER OF FILES FROM DEC20 TO TAPE


     @ENABLE (CAPABILITIES)
     $
     $;  Run OPR and initialise a tape with ANSI labels.....
     $
     $OPR
     OPR>SET TAPE-DRIVE MTA1: INITIALISE /LABEL-TYPE:ANSI-
     /VOLUME-ID:TREVOR
     OPR>
     14:11:12          -- MTA1: Volume TREVOR Initialised --
                     Label type: ANSI        Density: 1600

     14:11:13          -- INITIALISE Completed --
                     MTA1: available for user tape requests
     OPR>EX
     $
     $;   Now mount the tape.....
     $
     $MOUNT TAPE (NAME) TREVOR: /WRITE-ENABLED
     [Mount request TREVOR queued, request #1452]

     [Tape set TREVOR, volume TREVOR mounted]
     [TREVOR: defined as MT1:]
     $
     $;   Now we can copy all the files onto the tape....
     $
     $COP *.* TREVOR:,
     $$ASCII NOPARITY
     $$; Noparity is the default
     $$
      PMSPLN.TXT.1 => MT1:PMSPLN.TXT.131071 [OK]
      VAX.MEM.1 => MT1:VAX.MEM.131071 [OK]
      VAXPLN.MEM.1 => MT1:VAXPLN.MEM.131071 [OK]
      VAXPMS.TXT.1 => MT1:VAXPMS.TXT.131071 [OK]
      VAXPOS.TXT.1 => MT1:VAXPOS.TXT.131071 [OK]
     $
     $;    and dismount the tape....
     $
     TRANSFER OF FILES FROM DEC20 TO VAX                 Page C-2


     $DISMOUNT TAPE (NAME) TREVOR:
     [Tape dismounted, logical name TREVOR: deleted]
     $
     TRANSFER OF FILES FROM DEC20 TO VAX                 Page C-3


     C.2  TRANSFER FROM TAPE TO VAX


     $
     $ !    get where we want to be....(like TOPS20 CONNECT)
     $
     $ SET DEFAULT  [MOORE.US]
     $
     $ !    now mount the tape.....
     $
     $ MOUNT MSA0: TREVOR
     volume is write locked
     TREVOR mounted on _MSA0:
     $
     $ !    receive cheery VMS message.
     $ !    we check that it is all there with the DIRECTORY command
     $
     $ DIR MSA0:

     Directory MSA0:[]

     PMSPLN.TXT;32767  VAX.MEM;32767   VAXPLN.MEM;32767  VAXPMS.TXT;1
     VAXPOS.TXT;32767

     Total of 5 files.
     $
     $ !    VMS rewinds for you so we can
     $ !    now copy the files
     $
     $ COPY MSA0:*.*;* [MOORE.US]*.*;*
     $
     $ !    VMS' default is not to tell you unless it fails
     $ !    so we check....
     $
     $ DIR

     Directory US1:[MOORE.US]

     MYNOTE.MEM;1      MYNOTE.RNO;3      PMSPLN.TXT;32767  VAX.MEM;1
     VAXPLN.MEM;32767  VAXPMS.TXT;32767  VAXPOS.TXT;32767

     Total of 7 files.
     $
     $ !    now change these silly generation numbers....
     $
     $ REN *.*;32767 *.*;1
     $
     $ !    RENAME is like TOPS20 but agin default is no confirmation.
     $











                              APPENDIX D

                     STAGES OF PROGRAM CONVERSION



     D.1  SUMMARY

          This appendix deals with the stages in  converting  the
     program code as distinct from the data base conversion which
     is discussed in Section 8 and Appendix E.  There were  three
     distinct stages to the conversion which are discussed below.
     These were firstly the straight conversion  of  COBOL  code,
     secondly  the  conversion of the screen handling and finally
     testing and bug fixing.



     D.2  STRAIGHT COBOL CONVERSION

          This involved the removal of all Macro  calls  and  the
     conversion of all DML statements to achieve a clean compile.
     All the database error handling that used  declaratives  was
     amended  and  tests  for  success status after each database
     access were inserted.

          Transactions (OPEN/CLOSE) which exist  in  DBMS20  were
     replaced  by  READY  and  COMMIT/ROLLBACK  on the VAX.  (See
     Appendix E.)



     D.3  SCREEN CONVERSION.

          There were three general problem  areas  that  required
     consideration.  These were

          1.  retaining special functions keys,

          2.  providing user help and

          3.  limiting the size of the TDMS libraries.
     STAGES OF PROGRAM CONVERSION                        Page D-2


     D.3.1  Special Function Keys

          The functionality of these keys had to remain, although
     the actual keys were replaced with meaningful Gold keys.

     The following function keys were used:

          KEY            FUNCTION               REPLACING        RETURN 
                                                                INDICATOR 
                                                                  VALUE
          ---------------------------------------------------------------
          GOLD U-p       step up a field        Line Feed           3
          GOLD D-own     step down a field      CR/normal input     5 
          GOLD X-exit    abort/exit             Down Arrow          6
          GOLD B-ack     step back a page/form  Up Arrow            7 
          GOLD F-orward  step forward           Not applicable      8

     NB: A return indicator of 5 is always returned from a request
         unless one of the functions keys is used




     D.3.2  Providing User Help

          As one of the modules required full screen  help  on  a
     per  field  basis  which was implemented directly within the
     program code, we retained this  help  text  including  VT100
     cursor  control  sequences,  since this caused no problem to
     TDMS.  TRAFFIC users will recall that this is a problem when
     using  version  2.0 of TRAFFIC.  It is, however, unfortunate
     that there is  no  way  of  forcing  a  CONTROL-W  (re-paint
     screen)  from  within  the  code,  so  it  was  necessary to
     redisplay after each help request,  which  of  course  takes
     time.



     D.3.3  TDMS Library Size

          The two main screen i/o  modules  (PLNTIN  and  INPUTR)
     were converted using a different method for each.  Initially
     it was thought that it would be necessary  to  replace  each
     individual  TRAFFIC  call  by one TDMS request.  The problem
     with this would have been a request library which  contained
     a  large  number  of requests.  Since the request library is
     searched  sequentially   at   run-time   there   were   some
     unattractive   performance   implications   with  this.   As
     competence with TDMS increased it was possible to avoid  the
     large libraries which it was feared would result from taking
     this approach.  (See Appendix G.)
     STAGES OF PROGRAM CONVERSION                        Page D-3


     D.4  TESTING AND BUG FIXING

          Testing and bug fixing constituted a fairly large  part
     of  the  program conversion effort.  This was mainly because
     of the lack of functional and in-program documentation,  and
     the  relatively  poor  quality  of  the  code  itself.   The
     conversion brought  to  light  some  existing  bugs  in  the
     original  program suite (which were of course also converted
     because the exercise was to achieve an identical, or  nearly
     identical, copy!!).

          The small Cobol only or Cobol with DML modules required
     simple testing and the very few bugs that came to light were
     to do with either the difference in data  structure  or  the
     difference between initialising variables on the 20 and Vax.

          The major screen modules required  the  most  time  and
     effort to test and debug.



     D.4.1  PLNTIN

          This module probably  took  the  longest  to  obtain  a
     satisfactory working copy for the following reasons:

           o  it was the first screen module to be  converted  so
              inevitable mistakes using TDMS were made.

           o  the degree of re-structuring made it  necessary  to
              understand in detail the function of the module.

           o  testing of the function/logic of the module as well
              as conversion changes was required.




     D.4.2  INPUTR

          The second method of screen conversion was  applied  to
     this  module.   As  this  method  requires  no change to the
     fundamental  program  logic  and  structure,   testing   and
     debugging  was  simpler  than with PLNTIN (see above).  Some
     time was wasted due to errors with the database conversion -
     when  unloading  and  reloading  the data base some data was
     lost.  Time was also lost  chasing  after  bugs  which  also
     existed in the original 20 version.











                              APPENDIX E

                     EXAMPLES OF DBMS DIFFERENCES



     E.1  DEFINITION OF SCHEMA AND STORAGE SCHEMA

     E.2  SELECTED DML EXAMPLES


     SCHEMA SECTION.
             INVOKE SUB-SCHEMA plntss OF SCHEMA pms.                 20

     SUB-SCHEMA SECTION.
             DB nysub WITHIN pms.                                    VAX

     OPEN TRANSACTION modify-list.                                   20
     READY list-area CONCURRENT UPDATE.                              VAX


     FIND NEXT RECORD OF list-mle-set SET.                           20
     FETCH NEXT WITHIN list-mle-set.                                 VAX


     FIND list-record VIA CURRENT OF list-set USING list-key.        20
     FETCH FIRST list-record WITHIN list-set USING list-key.         VAX


     FIND NEXT input-list-record RECORD OF list-set SET.             20
     FETCH NEXT list-record WITHIN list-set.                         VAX


     CLOSE TRANSACTION modify-list.                                  20
     COMMIT.                                                         VAX




     E.2.1  DBMS Error Handling


     *************
     DECLARATIVES.
     *************
     EXAMPLES OF DBMS DIFFERENCES                        Page E-2


     FIND-END SECTION.
     *****************
             USE FOR DB-EXCEPTION ON dbm$_end.

     FE-01.
             SET no-record TO true.

     FE-END.
             EXIT.


     OWNER-ERROR SECTION.
     ********************
             USE FOR DB-EXCEPTION ON dbm$_cstyp_null.

     OE-01.
             SET no-owner TO true.

     OE-END.
             EXIT.











                              APPENDIX F

                    EXAMPLES OF COBOL DIFFERENCES



     F.1  SELECTED COBOL EXAMPLES


     Example 1.

     WORKING-STORAGE SECTION.
     ************************
     01      ACTION-FLAG             PIC S9(10)      COMP.
             88      GET-OUT-NOW             VALUE 1.
             88      WILL-EXIT               VALUE 2.
             88      PREVIOUS-MENU           VALUE 3.
             88      CONTINUE-PROCESS        VALUE 4.

     PROCESSING-SECTION.
     *******************
             SET action-flag TO 1.                   20

             MOVE 1 TO action-flag.                  VAX
             SET get-out-now TO true.                VAX

     Example 2.

     ID DIVISION.                                    20

     IDENTIFICATION DIVISION.                        VAX

     Example 3.

     FILE-CONTROL.

             SELECT updater-file ASSIGN TO dsk1
                     RECORDING MODE ASCII
                     file-status IS fs-1,fs-2,fs-3.          20



             SELECT updater-file ASSIGN TO dsk1
                     file status IS fs-1.                    VAX
     EXAMPLES OF COBOL DIFFERENCES                       Page F-2











                              APPENDIX G

                      SCREEN CONVERSION OPTIONS



          Two methods of screen conversion were used.



     G.1  METHOD 1

          This method made use of TDMS in more like the  way  the
     designers  had  probably  intended  it  to  be  used.   This
     required  a  limited  amount  of  restructuring   and   used
     multi-function  TDMS  requests.  A multi-function request is
     one which can itself clear the screen, display a form,  read
     fields  and  make  decisions  from  within a single request.
     This method,  although  providing  a  cosmetically  pleasing
     finished module, proved to be more difficult to achieve than
     anticipated.



     G.2  METHOD 2

          This method replaces TRAFFIC  call  for  call  by  TDMS
     requests.   It  defines  a  TDMS  control  field in a single
     program-wide request which is then mapped one  to  one  with
     TRAFFIC section or field numbers.











                              APPENDIX H

                     SCREEN HANDLING COMPARISONS



     H.1  REPLACING TFRERR


     *       ENTER MACRO tfrerr USING "Incorrect use of function key." 
                                       error-status error-code.

             CALL "tss$write_msg_line" USING BY REFERENCE channel,
                                             BY DESCRIPTOR "Incorrect use of function key." 




     H.2  EXAMPLE OF MULTI-FUNCTION REQUEST

     H.2.1  COBOL CODE


     *       ********************************************************
     *       * move formatted lines to the screen display variables *
     *       ********************************************************
             PERFORM VARYING wk_count FROM 1 BY 1 UNTIL wk_count > 20
                     MOVE list_line(wk_count) TO plntin_list_line(wk_count)
             END-PERFORM.

             SET unfinished TO true.
             MOVE spaces TO plntin_list_choice.
             MOVE "1" TO plntin_list_page_no.
             MOVE total_lists TO list_val.
             
     FULL-04.
             SET unfinished TO true.

             PERFORM UNTIL finished

                     IF plntin_list_page_no = "1"
                     THEN    MOVE "F forward page" TO list_page
                     ELSE    MOVE "B back page" TO list_page
                     END-IF

                     MOVE list_message TO plntin_list_message
     SCREEN HANDLING COMPARISONS                         Page H-2



     *               **********************************
     *               * display page and accept choice *
     *               **********************************
                     CALL "TSS$REQUEST" USING BY REFERENCE channel,
                                              BY REFERENCE library-id,
                                              BY DESCRIPTOR request-list(2),
                                              BY REFERENCE plntin_work
                                        GIVING status-result

                     PERFORM CHECK

                     PERFORM read-list-choice

             END-PERFORM.

             IF get-out-now OR will-exit OR previous-menu
                     GO TO full-exit.




     H.2.2  TDMS REQUEST


     FORM IS PLNTIN_LIST_SCREEN;
     RECORD IS PLNTIN_WORK;

     RETURN "5" TO PLNTIN_END_IND;

     PROGRAM KEY IS GOLD "X"
             NO CHECK;
             RETURN "6" TO PLNTIN_END_IND;
     END PROGRAM KEY;

     PROGRAM KEY IS GOLD "B"
             NO CHECK;
             RETURN "7" TO PLNTIN_END_IND;
     END PROGRAM KEY;

             USE FORM PLNTIN_LIST_SCREEN;

             CONTROL FIELD IS PLNTIN_LIST_PAGE_NO
                     "1":
                     OUTPUT PLNTIN_LIST_LINE[1 TO 10] TO PLNTIN_LIST_DETAIL[1 TO 10];

                     "2":
                     OUTPUT PLNTIN_LIST_LINE[11 TO 20] TO PLNTIN_LIST_DETAIL[1 TO 10];
             END CONTROL FIELD;

             OUTPUT "  " TO PLNTIN_LIST_CHOICE;
             OUTPUT PLNTIN_LIST_MESSAGE TO PLNTIN_LIST_MESSAGE;
             INPUT PLNTIN_LIST_CHOICE TO PLNTIN_LIST_CHOICE;

             RETURN "L" TO PLNTIN_SCREEN;
     SCREEN HANDLING COMPARISONS                         Page H-3



     END DEFINITION;




     H.3  REPLACING TFRRD

     H.3.1  COBOL CODE


     STANDARD-READER SECTION.
     ************************
     SR-1.

     *       ENTER MACRO tfrrd USING fieldz end-ind error-code.

             MOVE spaces TO inputr_reading.
             MOVE fieldz TO inputr_field_no.

             CALL "tss$request"
                     USING BY REFERENCE channel,
                     BY REFERENCE library-id,
                     BY DESCRIPTOR request-list(1),
                     BY REFERENCE inputr_work,
                     GIVING status-result.
             PERFORM check.

     *       *************************************************
     *       * move data read to the 'old' traffic variables *
     *       *************************************************
             EVALUATE fieldz

             WHEN 25 thru 38
                     MOVE inputr_reading TO value-array(fieldz - 24)

             WHEN 81
                     MOVE inputr_choice TO inp-choice

             WHEN 122
                     MOVE inputr_page_choice TO pag_choice

             WHEN 90
                     MOVE inputr_reading TO inp-inf-value

             WHEN 132
                     MOVE inputr_choice TO inp-inf-choice

             END-EVALUATE.

             MOVE inputr_end_ind to end-ind.

             IF end-ind = 1 
                     GO TO sr-2.
     SCREEN HANDLING COMPARISONS                         Page H-4


     H.3.2  TDMS REQUEST


     FORM IS INPUTR;
     FORM IS INPUTR_VALIDN_SCREEN;
     RECORD IS INPUTR_WORK;

     RETURN "5" TO INPUTR_END_IND;

     PROGRAM KEY IS GOLD "X"
             NO CHECK;
             RETURN "6" TO INPUTR_END_IND;
     END PROGRAM KEY;

     PROGRAM KEY IS GOLD "B"
             NO CHECK;
             RETURN "7" TO INPUTR_END_IND;
     END PROGRAM KEY;

     PROGRAM KEY IS GOLD "F"
             NO CHECK;
             RETURN "8" TO INPUTR_END_IND;
     END PROGRAM KEY;

     PROGRAM KEY IS GOLD "U"
             NO CHECK;
             RETURN "3" TO INPUTR_END_IND;
     END PROGRAM KEY;

             CONTROL FIELD IS INPUTR_FIELD_NO

             "025":  USE FORM INPUTR;
                     INPUT READING[1] TO INPUTR_READING;
             "026":  USE FORM INPUTR;
                     INPUT READING[2] TO INPUTR_READING;
             "027":  USE FORM INPUTR;
                     INPUT READING[3] TO INPUTR_READING;
             "028":  USE FORM INPUTR;
                     INPUT READING[4] TO INPUTR_READING;
             "029":  USE FORM INPUTR;
                     INPUT READING[5] TO INPUTR_READING;
             "030":  USE FORM INPUTR;
                     INPUT READING[6] TO INPUTR_READING;
             "031":  USE FORM INPUTR;
                     INPUT READING[7] TO INPUTR_READING;
             "032":  USE FORM INPUTR;
                     INPUT READING[8] TO INPUTR_READING;
             "033":  USE FORM INPUTR;
                     INPUT READING[9] TO INPUTR_READING;
             "034":  USE FORM INPUTR;
                     INPUT READING[10] TO INPUTR_READING;
             "035":  USE FORM INPUTR;
                     INPUT READING[11] TO INPUTR_READING;
             "036":  USE FORM INPUTR;
                     INPUT READING[12] TO INPUTR_READING;
     SCREEN HANDLING COMPARISONS                         Page H-5


             "037":  USE FORM INPUTR;
                     INPUT READING[13] TO INPUTR_READING;
             "038":  USE FORM INPUTR;
                     INPUT READING[14] TO INPUTR_READING;
             "081":  USE FORM INPUTR;
                     OUTPUT " " TO CHOICE;
                     INPUT CHOICE TO INPUTR_CHOICE;
             "122":  USE FORM INPUTR;
                     INPUT PAGE_CHOICE TO INPUTR_PAGE_CHOICE;
             "132":  USE FORM INPUTR_VALIDN_SCREEN;
                     OUTPUT " " TO VALIDN_CHOICE;
                     INPUT VALIDN_CHOICE TO INPUTR_CHOICE;
             "090":  USE FORM INPUTR_VALIDN_SCREEN;
                     INPUT VALIDN_READING TO INPUTR_READING;

             END CONTROL FIELD;

     END DEFINITION;




     H.4  REPLACING TFRWRT

     H.4.1  COBOL CODE


     *               MOVE inp-last-value TO data-val(page-no,line-no),
     *                               value-array(line-no)
     *               enter macro tfrwrt using field-no error-code

                     MOVE inp-last-value TO data-val(page-no,line-no),
                                     value-array(line-no),inputr_reading
                     MOVE field-no TO inputr_field_no
                     CALL "tss$request" USING BY REFERENCE channel,
                                              BY REFERENCE library-id,
                                              BY DESCRIPTOR request-list(3),
                                              BY REFERENCE inputr_work,
                                        GIVING status-result
                     PERFORM check




     H.4.2  TDMS REQUEST


     FORM IS INPUTR;
     RECORD IS INPUTR_WORK;

     USE FORM INPUTR;

             CONTROL FIELD IS INPUTR_FIELD_NO

             "025":  OUTPUT "          " TO READING[1];
     SCREEN HANDLING COMPARISONS                         Page H-6


                     OUTPUT INPUTR_READING TO READING[1];
             "026":  OUTPUT "          " TO READING[2];
                     OUTPUT INPUTR_READING TO READING[2];
             "027":  OUTPUT "          " TO READING[3];
                     OUTPUT INPUTR_READING TO READING[3];
             "028":  OUTPUT "          " TO READING[4];
                     OUTPUT INPUTR_READING TO READING[4];
             "029":  OUTPUT "          " TO READING[5];
                     OUTPUT INPUTR_READING TO READING[5];
             "030":  OUTPUT "          " TO READING[6];
                     OUTPUT INPUTR_READING TO READING[6];
             "031":  OUTPUT "          " TO READING[7];
                     OUTPUT INPUTR_READING TO READING[7];
             "032":  OUTPUT "          " TO READING[8];
                     OUTPUT INPUTR_READING TO READING[8];
             "033":  OUTPUT "          " TO READING[9];
                     OUTPUT INPUTR_READING TO READING[9];
             "034":  OUTPUT "          " TO READING[10];
                     OUTPUT INPUTR_READING TO READING[10];
             "035":  OUTPUT "          " TO READING[11];
                     OUTPUT INPUTR_READING TO READING[11];
             "036":  OUTPUT "          " TO READING[12];
                     OUTPUT INPUTR_READING TO READING[12];
             "037":  OUTPUT "          " TO READING[13];
                     OUTPUT INPUTR_READING TO READING[13];
             "038":  OUTPUT "          " TO READING[14];
                     OUTPUT INPUTR_READING TO READING[14];

             END CONTROL FIELD;

     END DEFINITION;




     H.5  REPLACING TFRCHG

     H.5.1  CDD Work Area


             INPUTR_VIDEO_ATTRIBUTES STRUCTURE.
                     INPUTR_VIDEO    DATATYPE TEXT 1 OCCURS 14 TIMES.
             END INPUTR_VIDEO_ATTRIBUTES STRUCTURE.




     H.5.2  COBOL CODE


     *       enter macro tfrchg using field-no 'NORMAL' error-code.
             MOVE spaces TO inputr_video_attributes.
             MOVE "7" TO inputr_video(field-no - 24).
             CALL "tss$request" USING BY REFERENCE channel,
                                      BY REFERENCE library-id,
     SCREEN HANDLING COMPARISONS                         Page H-7


                                      BY DESCRIPTOR request-list(5),
                                      BY REFERENCE inputr_work,
                                GIVING status-result.
             PERFORM check.


     *               ENTER MACRO TFRCHG USING COL-5 'REVERSE-VIDEO' ERROR-CODE
     *               ENTER MACRO TFRCHG USING COL-5 'BOLD' ERROR-CODE.
                     MOVE spaces TO inputr_video_attributes
                     MOVE "5" TO inputr_video(col-5 - 24)
                     CALL "tss$request" USING BY REFERENCE channel,
                                              BY REFERENCE library-id,
                                              BY DESCRIPTOR request-list(5),
                                              BY REFERENCE inputr_work,
                                        GIVING status-result
                     PERFORM check.




     H.5.3  TDMS REQUEST


     FORM IS INPUTR;
     RECORD IS INPUTR_WORK;

     USE FORM INPUTR;

             CONTROL FIELD IS INPUTR_VIDEO[1 TO 14]
                     "1":    BLINK FIELD READING[%LINE];
                     
                     "2":    REVERSE FIELD READING[%LINE];
                             BLINK FIELD READING[%LINE];

                     "3":    BLINK FIELD READING[%LINE];
                             REVERSE FIELD READING[%LINE];
                             BOLD FIELD READING[%LINE];

                     "4":    BLINK FIELD READING[%LINE];
                             BOLD FIELD READING[%LINE];

                     "5":    REVERSE FIELD READING[%LINE];
                             BOLD FIELD READING[%LINE];

                     "6":    REVERSE FIELD READING[%LINE];
             
                     "7":    RESET FIELD READING[%LINE];
             
             END CONTROL FIELD;

     END DEFINITION;