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Thread: Is 640KB TPA for CP/M-68K enough for all CP/M-68K applications?

  1. #1

    Default Is 640KB TPA for CP/M-68K enough for all CP/M-68K applications?

    I designed a CP/M-ready 68000 SBC for RC2014 bus. The SBC has 2 meg of memory. I like to partition the memory into TPA and RAMdisk. I'm thinking of 640KB for TPA and the remaining memory for RAMdisk but I don't know if 640KB TPA is sufficient for all known CP/M-68K applications. Does anyone know how much TPA the biggest CP/M-68K uses?

  2. #2
    Join Date
    Dec 2016
    New Jersey


    This is a very broad question that would be difficult to answer definitively. So little commercial software was released for CP/M 68K and it was largely abandoned by both its users and Digital Research. 68K enthusiasts preferred OS-9, Unix, or bought a Mac, Amiga, or Atari ST. Heck even the KaOS operating system was probably more successful.

    As a result CP/M 68K really only shipped with a handful of expensive systems as an option (SAGE, etc.)

    Of the commercial binaries I can find on the net and from memory none took more than ~300K. Binary size is not even a good indicator of memory usage, for example the Binary size of Pascal for CP/M 68K is 250K but it only requires 128K to run. It must use overlays.

    Maybe someone wrote some CAD software for the SAGE or similar that eats up more TPA than 300K, but my instinct tells me 640K would be memory than anyone would ever need for CP/M 68K.

  3. #3


    Thank you for the insight to CP/M 68K usage. It is indeed an unpopular version of CP/M. A shame, so much energy expended in maximizing the TPA of CP/M 3 can be easily solved with the 16-meg memory space of 68000. So then, I think it would be safe to assign 384K to TPA, 1.5 meg to RAM disk and the remains 128K to CP/M itself plus monitor/debugger/utilities outside of CP/M's domain. Thanks,


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