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DOS Memory Management

DOS Memory Management

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Comments (25)

  • 5o1ecist
    I remember UMB. I remember that, as a teenager, I was obsessed with figuring out how to squeeze the most free conventional memory out of MS-DOS 6+ ... or 7+? I was stuck at around 615k, maybe 620ish. It annoyed me greatly, because I knew there was still headroom left.The thing was, that upper memory wasn't just for TSRs. Anything one can shove there, would happily stay there and run just fine.My journey towards the most free, conventional memory ended at 637k on my 386 DX-33 with 8megs of RAM and a SoundBlaster card, with everything possible being shoved to high memory. Mouse driver, MSCDEX and even COMMAND.COM.637k. So proud, much wow!Good times!
  • markus_zhang
    I have to admit, DOS memory management is very fascinating to me as a very amateur kernel investigator. I have a book called “DOS beyond 640k” which describes all sorts of extensions people back in the 80s invented to get as much free memory as possible. The contents of course are irrelevant nowadays, but it is still interesting to read as a tech book.
  • sqldba
    There's a retail tool that lets you get a lot more memory below 1MB. 639K (625K free) conventional, 262K upper (177K free).If you remember seeing how, you'll get a free virtual cookie.
  • throw0101c
    No discussion on the topic would be complete without QEMM:* https://en.wikipedia.org/wiki/QEMM
  • nnevatie
    Good times. Our DOS game PaybackTime 2 was only capable of using conventional memory. That was a major reason for the game really not having any proper animations for its player characters.
  • gschizas
    'MZ' has been confirmed to be the initials of Mark Zbikowski, there's no question about it. It's not "Memory" + "Last".
  • esafak
    Lacking a discussion on protected mode; the means to access the 1MB+ area (up to 16MB in 286, and 4GB in 386 and later).https://en.wikipedia.org/wiki/DOS_Protected_Mode_Interface https://en.wikipedia.org/wiki/Virtual_Control_Program_Interf...I remember toying with DPMI in assembler.
  • ubermonkey
    Mmmm, flashbacks of complex sets of AUTOEXEC.BAT & CONFIG.SYS files that we'd swap in and out using batch files to support different memory configurations...
  • mlvljr
    [dead]