First - that's very interesting research and glad to read about it (esp. remember some switch/relay/light versions of the FoxHenCorn puzzle as well as Nim, and they remind me of the Claude Shannon maze solving mouse in SciAM. I almost had that schematic memorized but never built one. It had a 3 bit memory so it could 'learn' a 3 fork maze, and a rotating 'randomizer' for the one's the mouse didn't know. My 'first' personal computer then was made out of a piece of fence, 24 or so nails, a 'D'cell, 3 or 4 lamps and a lot of hookup wire) B_b_b_but Berkeley Ent. didn't really market it as a personal *home* computer, looks like the target audience they hope to sell into is advertising gimmicks, 'show stoppers'. Also, unlike other machines sold to academia or business uses, the Altair was marketed to people who buy or build their own HI-FI/Stereos, CB/Ham radios - i.e., the HOME hobbyist. For $60/ month. I can own my OWN computer, free and clear to do whatever I want with, not limited by the funding strings that dictate what I can do with one at work or at school. Free at last!! Again, without any further defining guidelines, other than the default Intel ('PC') lineage, and a tip of the hat to the unsuccessful Mark-8, I posit that the 'first PC's' are the abacus, knots on string, pushing stones around on tables, Napiers bones, slide rules - or does it have to include an 'active' element (relay, tube, transistor, IC)? I'm lost as far as what your qualifying criteria is. Of course, one can always custom tailor their list of criteria so that the machine you've already chosen as 'first' comes out as such, post facto, hehe. Chuck cswiger(a)widomaker.com