moshix.mvs/PC370_orig/Diskette/full/DOC/HELP.DOC

 
PC/370 help documentation

So you've successfully installed PC/370 using the BAT\INSTALL.BAT
command, have run the demo programs, and have read the documentation
files, but you still have some questions.  Well, here are some of the
most frequently asked questions and some answers which may help:

  1.  Where can I get more help?

      Send letter and/or diskette with problem to me at the address
      listed below and I will reply.  Subscribe to Compu-Serve
      electronic mail survice adn send me EASY mail message
      using ID# 73047,1113.

  2.  The A370.EXE cross assembler gets I/O error reading my source
      ALC program file?

      The file must be in ASCII text form with line feed (X'0A')
      character ending each line of text.  This is standard PC format
      used by most text editors including EDLIN and SEE.  If the ALC
      file was downloaded from an IBM mainframe, it may need to be
      translated from EBCDIC to ASCII.  Most mainframe to PC link
      facilities have this translation option as a default.

  3.  The A370.EXE cross assembler did not recognize some statements?

      See USER.DOC for OS/VS assembler features not supported by
      A370.EXE such as macros, and see the reference section for
      additional texts on OS/VS assembler and ASSIST.  If the program
      has macros, you must use the M370.COM macro preprocessor to
      expand macros into basic assembler first.  If the program has
      floating point E, D, or L type DC constants, an 80x87 math co-
      processor must be installed for the assembler to correctly
      assemble the floating point constants.

  4.  The L370.EXE linkage editor keeps getting unresolved external
      references even though I've checked that all subroutines have
      been added to system or program LIB file with correct /B option
      of MS-DOS copy command as shown in BAT\BLDLIB.BAT?

      The linkage editor scans the program LIB file first and then the
      system LIB file in sequential order attempting to resolve all
      external references in one pass.  If any module selected for
      inclusion calls a module previously scanned and not selected,
      then the link will fail as a result of the backward reference.
      You must sequence the libraries to eliminate backward references
      or force loading of required modules with explicit external
      address constants.  To allow unresolved references use option U.

  5.  My first program will not run.  How do I debug it?

      Specify an upper case T as only parameter when executing program
      to start in debug mode or link it with option D specified.  At
      the interactive debug prompt, type T to trace instructions up to
      point of failure.  You can stop trace at any point by hitting
      any key and then typing T again to restart.  If no entry point
      name was specified on END statement, the program will start at
      first byte of code.  If there are too many instructions before
      failure to trace, enter Q for quiet mode execution up to point
      of failure and then enter N for list of last 20 instructions
      executed.  See debug chapter of USER.DOC for more information.

  6.  My write to operator message printed garbage after message?.

      Add $ character to tell MS-DOS where end of text is.

  7.  My first file I/O operation caused an I/O error?

      Make sure that file is in current directory or that complete
      MS-DOS file path was specified in DCBDSN field of DCB with a
      trailing null character (X'00').  Make sure that record length
      (LRECL) includes room for carriage return and line feed
      characters in each text record.  Text record processing on the
      PC is quite different from the normal fixed length text record
      processing on an IBM mainframe.  Text records on the PC created
      by the SEE.COM full screen editor or most other PC editors such
      as EDLIN store text records in variable length ASCII form with a
      carriage return (X'0D') and line feed (X'0A') character
      indicating the end of each record and an end of file (X'1F')
      character after the last line feed.  If the file being read or
      written has 80 data characters, then the record length needs to
      be 82 bytes for text type files.  See SYSTEM.DOC for more
      information on file DCB options including translation between
      EBCDIC and ASCII.  The ASSIST extended instructions XREAD and
      XPRNT make the translation between ASCII text file format and
      EBCDIC fixed length record format automatically.  See the ASSIST
      demo programs DEMOAST1.ALC through DEMOAST4.ALC and the ASSIST
      section of USER.DOC for more information.

  8.  The records read from my input file appear to be in ASCII
      instead of EBCDIC as expected by the 370 program?

      The default for DCB text file processing is not to translate
      between ASCII and EBCDIC.  There is an option bit in the DCBFLG
      byte named DBTRAN which can be set prior to open to request that
      each record be translated such that file is in ASCII and record
      processed by program is in EBCDIC.  The ASSIST extended
      instructions XREAD and XPRNT automatically make this
      translation.

  9.  Why don't you have an option to let all character strings
      default to ASCII instead of EBCDIC code in an assembler program?

      Release 1 did have option E to specify either ASCII or EBCDIC
      for DC character strings and self defining character strings
      such as immediate data in CLI instruction.   This created non-
      standard 370 code by default when the ASCII mode was selected
      and was very confusing when mixing subprograms with different
      options.  Release 2 removed the E option and added option to
      define ASCII character strings using double quotes.   This
      solution also allows both types of character strings to be
      easily used in a single program.

 10.  Can I download and use the MVS, VM, or VSE macro's?

      No.  First they are copyright by IBM and licensed only on the
      mainframe they reside on.  Second, they would not work without
      changing them to use PC/370 supervisor calls and the limited
      syntax of the macro pre-processor.  The common MVS macros
      included such as DCB, OPEN, CLOSE, GET, and PUT have been coded
      from scratch for the PC environment.  Several different users
      are developing additional macros to provide compatible unit test
      environments for each of the above operating systems.

 11.  Can I download load modules from an IBM mainframe and run
      them using PC/370?

      Yes, but only if you also complete a PC/370 shell such as the
      MVS demo shell to intercept all SVC's and supervisor state
      instructions used.  The demo shell will support a native 370
      mainframe MVS load module that only uses problem state
      instructions and the WTO and WTOR svc's.  The actual load module
      file would have to be processed to remove all the extraneous
      fetch control records leaving just the 370 object code in a MOD
      type file which could be loaded and executed by the shell
      program.  The object code would have to be self relocating (i.e.
      no relocation records in the load module file).

 12.  Can I download fixed blocked files and read them directly with a
      PC/370 program?

      Yes, one of the DCB file processing options is fixed blocked.
      This mode assumes that the file contains fixed length binary
      and/or EBCDIC data records with no carriage returns or line
      feeds.  Text files are not normally stored in this format on
      PC's because it wastes so much space compared to the variable
      length ASCII text format.

 13.  Can I upload source, object, or load modules to the mainframe
      and execute them?

      Yes, with the following restrictions:

        a. Source code must be translated back to EBCDIC and any SVC's
           or macros used must be compatible with the mainframe
           operating system and macro assembler.

        b. Object code can be uploaded after it is converted from
           compressed bit stream format (OBJ) to OS/VS linkage editor
           80 byte fixed blocked format (370) using the utility
           T370.COM which is included in both object and source form.
           This is being used by some software developers who unit
           test code on a PC and then upload tested object code to
           mainframe.

        c. Load module code can be uploaded but with the following
           restrictions.  Only MOD format code would make sense to
           upload since the loader code in COM format files is unique
           to PC MS-DOS environments.  An application interface on
           the mainframe would have to be written to read the MOD
           file code into memory and link to it.  Of course, the
           supervisor instructions would have to be compatible with
           the mainframe operating environment.

Please send additional questions and answers you think would be
helpful to other users.  I will add them with appropriate credits.
This file was first added in release 4.2 at the suggestion of BIll
Earle.

Don Higgins
6365 - 32 Avenue North
St. Petersburg, Florida 33710