Oh man, OS/2! Was so proud when i was finally able to afford 8MB RAM to get Warp 3 run smoothly...
Ah, memory lane (pun most definitely intended). My second computer, and first IBM-compatible, was a 486 DX/2 66MHz with a whopping 640KB of RAM. Yep, it had a single stick of 72-pin SIMM RAM with 640KB on it. Not sure who designed that frankenstein of a RAM stick, but it worked. I still have it on my keychain, to this day.