If you mean the most archeologically fascinating machine, well, I (and other here as well) had machines based on the
8080,
Z80, the
6502, and the
6510, all with tiny memory spaces (my smallest was 5KB total -- 4K in ROM and 1KB in RAM) and running at a then-standard 1MHz. For some of us, that would be represented by a hobby board with a hex keypad (if you were lucky -- many had nothing put a panel of toggle switches) for input and a series of LEDs for output. If you wanted more, like a keyboard or alphanumeric output, you needed to build an interface. For others, that machine would have been a Radio Shack
TRS-80, a
Timex/Sinclair/BBC unit, an
Apple ][, a
Heathkit/Zenith, or a Commodore
PET,
VIC-20 or
64. They weren't good for much except gaming (including some great educational games, which is why the Apple ][ family made good inroads in schools) and spreadsheets (
VisiCalc made a huge impact in the small-to-medium business space). Oh, and they were
great for learning about the technology and programming.
If you mean the most out-of-date machine I ever used compared to the ambient technology, well that would be the 4MB 486SX25 "grey box" I was running while the rest of the world was running Windows 95 on Pentium II MMX technology with 16 or 32 MB and 10x faster clock speeds. Writing code on that machine was no slower than it is today, but compiling it could literally take days. And I do remember doing a ray-traced 3D rendering (800x600 pixels, 24-bit colour with shadows) that took more than two weeks. Computing required a little more patience in those days...
