#1: (~1981)
Sinclair ZX81. Z80 CPU, 1K RAM, and I got the 16K RAM module. Stored BASIC programs on any audiocassette recorder.

#2: (~1983)
Atari 800XL. 6502C CPU, 64K RAM, and I also got an Indus GT "dual density" floppy drive. Did a lot of stuff with this box. I learned 6502 assembly language, and still have many manuals on that subject. Awesome game selection for this machine.

#3: (~1985?)
Texas Instruments TI-994A. See Vid\'s post above. Even when it was discontinued and with a reduced price, it was still a waste of money.
A bunch of other crap until I bought my first x86 based PC:
(~1993)
Zeos 486/66 w/win 3.11. A piece of crap before the Pentium existed, but it ran DOS games like Civilization, Doom, and X-Com pretty well. I remember I used to think the 486 was so incredibly fast compared to the 386s we used at work…:laughing: