There were plenty of hobbyist computers before the IBM PC (1981), but your timeline's a little off. Sure there were interesting things like the Altair and Heath-kit and other stuff before the PC, and the Apple I and II, 8 bit Ataris and VIC-20 predated it, but the real explosion of variety came after. The C=64 came out in '82, the Amiga in '85. Most notably, the Macintosh in 1984, of course. The Atari 1200 and successors came out in the early 80s. And if it weren't for Compaq making a widely available IBM work-alike around '83, the DOS (and then Windows) empire might never have risen with just Big Blue's hardware supporting it. (BTW, that Compaq "luggable" was quite a revolutionary computer at the time, being not only DOS compatible but portable in the sense that it had a handle and case.) And that's just the US: the Sinclair and BBC computers were popular in the UK, for instance. (An incredibly crappy but amazingly cheap version of the Sinclair -- $19.99 at my local drugstore!! -- appeared briefly in the US in a joint venture with Timex.)