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.<p>The thing was, that upper memory wasn't just for TSRs. Anything one can shove there, would happily stay there and run just fine.<p>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.<p>637k. So proud, much wow!<p>Good times!
I remember playing at least one game without the mouse, to save those precious KBs…
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.
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.