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Thread: GSX for CP/M 2.2

  1. #1

    Default GSX for CP/M 2.2


    I am working with some small CP/M 2.2 systems and would like to find more info on the GSX graphics system.
    There is some information about programming and a few drivers but much seems to be missing.
    My ultimate goal is to write some terminal screen drivers for the 8080/Z-80 GSX system - not for CP/M-86.

    The latest version of GSX-80 seems to be version 1.1 from November 1983.
    So far I found scans of the "GSX-80 Programmers Guide" (2 versions) and some .PRL drivers for printers and plotters, but no example source code for driver development.

    What I would like to find is the GSX Programmers Toolkit for CP/M-80 with its software and documentation.
    A DR newsletter states "GSX Programmers ToolKit is available for 8-bit and 16-bit systems and includes ISV redistribution license, tailoring tools and documentation."

    Also it would be nice to find a copy of "DR Access 10 für CP/M-80" which may include more drivers.

    I found a copy of an "xterm-Tektronix" screen driver by Udo Munk from 2014, but no source code.

    • Does someone have a copy of the "GSX Programmers Toolkit for CP/M-80" which could be copied/scanned?
    • Any source code examples for CPM-80 GSX drivers? Maybe not in RATFOR but C or assembler?


  2. #2
    Join Date
    Jun 2016
    Guisborough, England


    Hello Martin,

    Firstly, a BIG thank-you for your work with the HX-20, I've noted your doc regarding this machine (which I also have, still just about working).

    Regarding your present enquiry, I don't think I have what you're looking for, but I'll note what I do have.

    I have one of the Amstrad PCW machines, still working, still used. This came with GSX, and I did do some playing with the DR-Draw package which used GSX, a LONG time ago. I still have the DR-Draw package, and I assume it would still work. BUT, this all relates to CP/M 3, and not 2.2.

    I understand that the GSX package that was supplied with the PCW is somewhat 'cut-down' from the full system, but I'm not sure by how much. I read that various Input aspects are not there, maybe it's more complete regarding Output. There are only a few drivers for devices, and printers.

    In 1986 DR released a set of CP/M manuals to cash in on the PCW market, and I boughht the set. The set includes the full (I assume) manual for GSX, this includes the 'User's Guide' and the 'Programmer's Guide'. The latter includes substantial details of the interface between any driver that a programmer might with to create, and the GDOS. This is referred to as the VDI (Virtual Device Interface) and Appendix C in the manual covers this in some detail, BUT there seems to be ZERO examples, or any code.

    Appendix A & B does give some details of the Calling Conventions for invoking a device driver, depending on system.

    NB the only software I have is that which was supplied on the PCW system disks.

    John Elliott (who produced the Joyce PCW emulator which I think does support GSX) may well know a lot more.

    If anything I have might be relevant, do let me know. The manual I have could be scannable, it's not too big.

    Geoff Barnard
    Vintage Devices: Epson HX-20/TF-20, Amstrad PCW 8256 (with extras), 386 and 486 PCs with 5.25 and 3.5 floppy drives, Pentium 75 with Roland LAPC-I midi card

  3. #3



    thank you for your reply. The HX-20 is an interesting machine and after looking into it I obtained a PX-8. I could easily adapt the disk drive emulator to this system - and the PX-8 uses CP/M which is more versatile than the HX-20. I like the quality of the keyboard of both.

    The manuals you mentioned are already available - no need to scan. I also found that two versions of the Programmers exist and one contains an incomplete skeleton driver, written in RATFOR (i.e. FORTRAN!).
    I will experiment a bit with driver writing, maybe by disassembling one of the .PRL files to identify the structure.

    The Amstrad CP/M and GSX drivers are more advanced and most of the documentation about GSX id for CP/M-86 and finally for GEM.


  4. #4


    To close this question:

    In the meantime I found some GSX driver collections on Udo Munk's web site
    He even provides his Tektronix driver source files in the GSX-1.0 archive.
    First I failed to extract the files .tar.gz because WinZip did not handle them correctly (it replaced CR characters with CR/LF in binary files...). So I had to use a Unix-like tool under Windows, in my case MSYS. CYGWIN and similar should work too (if you have no Linux system at hand).
    Next, I was struggling a while with the buggy MS-Fortran Compiler 3.4 and only after switching to version 3.44 I was able to build a working copy of his DDXTEK.PRL driver and to write my own DDHP2648.PRL driver.
    (Version 3.4 has a bug with indexing array elements in subroutines.)
    Finally, I learned that only the Digital Research linker LINK can produce the .PRL files - Microsoft L80 cannot do this.
    In terms of assembler RMAC as well as M80 can be used.

    So the key learning steps were:
    - go to Udo's web site to download the available GSX related files + get the GSX manuals from e.g.
    - use the proper archiver to unpack the files
    - use the proper compiler (avoid 3.4)
    - use the proper linker LINK 1.3



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