DOS Memory Management

3 days ago (os2museum.com)

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!

  • I remember playing at least one game without the mouse, to save those precious KBs…

  • 637k is pretty good! There was an automated command in later DOS versions that would try to optimise memory, but I don't think it got results as good.

    • MEMMAKER. It was okay, but it was so invasive in modifying your CONFIG.SYS and AUTOEXEC.BAT that I never really trusted it. I preferred hand-optimizing.

      1 reply →

  • I don't remember the exact number, but I remember that using memmaker and some manual fine-tuning, was on the 620-63X range of conventional RAM.

  • We did special boot disks to strip out everything but what was needed for the game, but sometimes we still couldn’t make it One day I went to a friends house and he had like way more conventional memory in memtest! What the hell I spent hours and days getting 620kb

    He was running Dr -dos

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.

'MZ' has been confirmed to be the initials of Mark Zbikowski, there's no question about it. It's not "Memory" + "Last".