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  1. Default TRSDOS/LSDOS 7x

    I wanted to ask here in this forum if there would be any interest in a new version of DOS for eZ80 that makes use of available legacy software.

    Many long hours led to a kernel similar to LOWCORE/SYSRES/SYS0 for TRS80 series of computers which I hope will allow SYS1-13 to execute unchanged using a eZ80 (or with minor patching).

    It is my goal of no reassembly of SYS1-13 but yet execute unchanged as much TRSDOS 6.x software as possible. This is accomplished thru very careful design details of this low memory kernel.

    I want to open up as much new modern hardware to older legacy software as possible. At the same time we must realize that we need to be open to new hardware that has not even been developed yet (like could they imagined CF storage cards in 1970's?).

    TRSDOS/LSDOS version 6 was to my knowledge the 1st time on TRS80 line they achieved near 100% hardware independence (or very near 100% was goal) between hardware and software.

    As it tells you in TRS80 programming manuals for version 6, use only OS service calls to communicate with hardware, never communicate directly between application and hardware.

    Programs and even sections of O/S code that followed this rule is then more easily portable to new hardware platforms.

    Remember, I don't care what computer it is or what language or compiler you have on this planet, you only see two things, memory & I/O.

    I said version 7x in subject line because well 6 is already taken and x for experimental. At this point I am experimenting and testing code I wrote for FLASH DRIVES, RAM DRIVES and what will and will not run. Video memory is simulated and pumped out serial port to a terminal. Networking software was developed and being developed which allows multiple CPU's executing LSDOS to share disk drives.

    Myself, I call this NeXTDOS. I feel its the 'next step' in all this evolution, an attempt to take TRSXXX to 24bit level.

    Only software developed using device independence will easily port over, no attempt to run model III software has been attempted in this project. It is my hope that all compilers and compiler generated code will execute unchanged.

    What ideas does this spark if any?

  2. #2


    Well behaving TRSDOS 6 applications should be portable across Model 4 and Model II, so this seems to be an attainable goal.

    In short, you are proposing a way of running legacy TRSDOS 6 applications on new modern Z80 based platforms. And also providing new APIs used to access modern accessories like flash drives and network adapters. Correct?

    This is very cool. Will you be open sourcing the software?

  3. Default

    Pete, generally what you are saying is correct.

    When I started out I wanted to be able to run my legacy software on a new modern eZ80 SBC. Looking around there was not one that was well suited for LS/TRSDOS 6.

    I started a rewrite anyway and at some point I realized LS/TRSDOS is very modular. Sys1-13 has very little connection directly to hardware but does have a direct connection to lowcore by calling absolute addresses in lowcore.

    At this point I am trying to develop a new BIOS/LOWCORE that has same entry points hoping perhaps we can run sys1-13 unchanged or minor patches. If it will not work out then it will only be a simple matter of reassembly of sys1-13 using updated lowcore entry points.

    Most all applications are already hardware independent. I was reading on one website where they recommended LS/TRSDOS 6 programmers to avoid using system supervisor calls (SVC) and just call routines directly in lowcore. This is not only the worst advise I have ever read about TRS80s but perhaps worst programming advice on web.

    I wonder if they have ever wrote what Roy Soltoff wrote about programming this machine or if they understand what it means?

    Follow rules for portability and all that hard work those folks put into it. Write portable software and we will try to see that it has something to run on in future.

    LSDOS 6 was superior to all other home O/S (CP/M MSDOS etc), so good in fact they killed it.

    Now that O/Ss such as Lunix is popular and more people are exposed/educated in Unix type O/S, they can see compressions of LS/TRSDOS to Unix (routing, linking, device independent etc). With their advanced overlay feature LS/TRSDOS was getting a lot of work out of an 8 bit machine.

    Yes with time I will publish source. Testing now of what works and don't work. I am looking for someone who is developing a eZ80 based SBC with banked memory.

    I simulate bank memory now with block moves which is slow but does allow bank memory.
    Video memory is simulated and blocked moved, all old video routines run and draws screens in this simulated memory.
    Adding a scheduler that allows you to run jobs unattended on a schedule.

    Mainly just trying to get a model working that allows for as much legacy code as possible to run.

  4. Default

    My experiments shows I can start up more that one instance of LS/TRSDOS running in multiple eZ80 64k memory banks. Each one thinks it is a dos running on its own machine.
    I want to now write code that allows them to network together.

    Like we did in old days on MVS. We had VM partitions and each partition was its own machine networked with others all inside same CPU.

  5. Default

    Many or several library commands will be purged from sys6, 7 and 8.

    New commands will need developed and replace these commands.

    New commands can be written in and language that compiles to a load module [fortran, compiled basic, C, etc]. Hopefully some of our C community will give us things like grep.

    In addition i am exploring adding ability to add additional user customizable library. This will allow special commands to be added depending on job dos is being used for [in a soda machine, gas pump, solar farm controller etc].

    Possibilities are everything with lsdos.

  6. #6
    Join Date
    Jan 2014
    Western North Carolina, USA


    I really like this idea. I've wanted to see an LS-DOS at the next level for a long time; I'm looking forward to this developing and to help out as I can. I'm more of a hardware guy, and so I'm going to put on the front burner an eZ80 design that will be a bit more LS-DOS friendly.

    The banked RAM isn't too hard, and, as long as we're willing to leave some of the older parts of the Model 4 design behind (memory-mapped keyboard, for instance, although mapping a USB keyboard to the TRS-80 memory map has been done, and done well) we could have a killer LS-DOS machine. I wouldn't even bother supporting floppies, but floppy and hard drive images on SD card would be something that I would think would be required. eZ80 has SPI in hardware, and there's a CP/M port for eZ80 that can drive an SD card on SPI.

    The eZ80's chip selects could be used to map the memory two ways, with linear memory on one chip select and 32K shadowed banked RAM on another chip select, with the hardware that does the mapping of the 32K lower bank paying attention to which chip select is in use, making it possible to run in ADL mode without polluting the memory space with extra 32K lower banks every 64K.... I've got some ideas on to get them into KiCAD.

    I guess the question is simply 'how much backwards compatibility is required' of such an eZ80 device. Hmmm, sounds like a poll in the making....
    Thus spake Tandy Xenix System III version 3.2: "Bughlt: Sckmud Shut her down Scotty, she's sucking mud again!"

  7. Default

    I was very happy to find this site because some time ago I started downsizing do to medical issues. Not only downsize but I have had an itch to finish some lifelong project dreams.

    Not to diverge from computers but in last few years I have had many surgeries and I do OK but, anesthesia always messes with me and sometimes I mix things up. For example I am afraid until I joined this forum I gave Tim Mann credit for wrong emulator. I even wrote him an email thanking him for job well done. I wondered why I didn't hear back LOL, I am sure he thought what a mixed up guy. OK, now I have it straight.

    What I wanted to say is that I see great interest here in retro side of trs80 but in as far as picking up and going forward from model 4 left off, its not a big interest. I have my reasons for wanting to go forward such as embedded controllers and educational etc.

    That being said I am preparing to publish source files so you yourself can boot my lowcore and run a partial LSDOS.

    What do I mean by partial? It loads lowcore and does all functions not needing overlays at this point. It then loads and runs a diagnostic to test RAM resident SVC functions. If they all pass it then tries to load sys1 from FLASH DRIVE starting at a specific location of flash memory but there is nothing in memory to load. From that point OS is scrolling disk error which it should and further proves its running correctly.

    Idea will be I only provide lowcore, you provide your own sys1-13.

    But for now its just a demonstration of how this could work. I can release a version of source files of when it worked as I described above and people can play with it and think about it.

    It is source revision that is several revisions back from where I am currently, but it is a good demonstration level.

    Also at this revision it runs using Zilog simulator software so you don't need actual hardware. This way everyone can try it no hardware needed but your own PC!

    Video is dumped to console screen and you can also examine video memory with debug monitor.

    Will update this post when it is ready and I think best way to distribute will be for me to email you project file after you download development software from Zilog.

    I need to get a technical description/ read me file made to go with source so I need some time. To complicate my medical life further I fell and fractured two bones in left wrist requiring surgery, 11 screws and plate. Sure makes typing hard.

    I will post again when I make some progress on read me for source. In mean time if you plan to run this project, download from Zilog their latest free software development system.

    Thanks for all the great conversations on this site, I have really enjoyed it.

    Daniel Martin

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