Forum etiquette

Our mission ...

This forum is part of our mission to promote the preservation of vintage computers through education and outreach. (In real life we also run events and have a museum.) We encourage you to join us, participate, share your knowledge, and enjoy.

This forum has been around in this format for over 15 years. These rules and guidelines help us maintain a healthy and active community, and we moderate the forum to keep things on track. Please familiarize yourself with these rules and guidelines.

Remain civil and respectful

There are several hundred people who actively participate here. People come from all different backgrounds and will have different ways of seeing things. You will not agree with everything you read here. Back-and-forth discussions are fine but do not cross the line into rude or disrespectful behavior.

Conduct yourself as you would at any other place where people come together in person to discuss their hobby. If you wouldn't say something to somebody in person, then you probably should not be writing it here.

This should be obvious but, just in case: profanity, threats, slurs against any group (sexual, racial, gender, etc.) will not be tolerated.

Stay close to the original topic being discussed
  • If you are starting a new thread choose a reasonable sub-forum to start your thread. (If you choose incorrectly don't worry, we can fix that.)
  • If you are responding to a thread, stay on topic - the original poster was trying to achieve something. You can always start a new thread instead of potentially "hijacking" an existing thread.

Contribute something meaningful

To put things in engineering terms, we value a high signal to noise ratio. Coming here should not be a waste of time.
  • This is not a chat room. If you are taking less than 30 seconds to make a post then you are probably doing something wrong. A post should be on topic, clear, and contribute something meaningful to the discussion. If people read your posts and feel that their time as been wasted, they will stop reading your posts. Worse yet, they will stop visiting and we'll lose their experience and contributions.
  • Do not bump threads.
  • Do not "necro-post" unless you are following up to a specific person on a specific thread. And even then, that person may have moved on. Just start a new thread for your related topic.
  • Use the Private Message system for posts that are targeted at a specific person.

"PM Sent!" messages (or, how to use the Private Message system)

This forum has a private message feature that we want people to use for messages that are not of general interest to other members.

In short, if you are going to reply to a thread and that reply is targeted to a specific individual and not of interest to anybody else (either now or in the future) then send a private message instead.

Here are some obvious examples of when you should not reply to a thread and use the PM system instead:
  • "PM Sent!": Do not tell the rest of us that you sent a PM ... the forum software will tell the other person that they have a PM waiting.
  • "How much is shipping to ....": This is a very specific and directed question that is not of interest to anybody else.

Why do we have this policy? Sending a "PM Sent!" type message basically wastes everybody else's time by making them having to scroll past a post in a thread that looks to be updated, when the update is not meaningful. And the person you are sending the PM to will be notified by the forum software that they have a message waiting for them. Look up at the top near the right edge where it says 'Notifications' ... if you have a PM waiting, it will tell you there.

Copyright and other legal issues

We are here to discuss vintage computing, so discussing software, books, and other intellectual property that is on-topic is fine. We don't want people using these forums to discuss or enable copyright violations or other things that are against the law; whether you agree with the law or not is irrelevant. Do not use our resources for something that is legally or morally questionable.

Our discussions here generally fall under "fair use." Telling people how to pirate a software title is an example of something that is not allowable here.

Reporting problematic posts

If you see spam, a wildly off-topic post, or something abusive or illegal please report the thread by clicking on the "Report Post" icon. (It looks like an exclamation point in a triangle and it is available under every post.) This send a notification to all of the moderators, so somebody will see it and deal with it.

If you are unsure you may consider sending a private message to a moderator instead.

New user moderation

New users are directly moderated so that we can weed spammers out early. This means that for your first 10 posts you will have some delay before they are seen. We understand this can be disruptive to the flow of conversation and we try to keep up with our new user moderation duties to avoid undue inconvenience. Please do not make duplicate posts, extra posts to bump your post count, or ask the moderators to expedite this process; 10 moderated posts will go by quickly.

New users also have a smaller personal message inbox limit and are rate limited when sending PMs to other users.

Other suggestions
  • Use Google, books, or other definitive sources. There is a lot of information out there.
  • Don't make people guess at what you are trying to say; we are not mind readers. Be clear and concise.
  • Spelling and grammar are not rated, but they do make a post easier to read.
See more
See less

GSX for CP/M 2.2

  • Filter
  • Time
  • Show
Clear All
new posts

    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?


    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



      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.



        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



          Finally I wrote some brand new drivers for GSX-80 under CP/M 2.2 to support my devices of interest:

          Some notes on these and other drivers in




            thanks for your work...