I still love the old 8-bit CPUs like the Zilog Z80. The fact that it's survived so long and become used as a secondary processor for disk controllers, keyboards, etc. just shows what a great CPU it was. Full credit to the 8080 for starting it (the Z80 was designed as an "extended 8080" and will run 8080 code).

The Acorn machines I mentioned above were based on the 6502, which was also used in a lot of the Commodore machines of the time. A teacher at my old school had a homebrew 6800-based system which I played around with sometimes as well. Each of these CPUs had slightly different register combinations and addressing modes.

Lance, you mentioned the XT and AT. The original IBM PC (model 5150) was launched in 1981 with the 8088 processor. The XT (eXtended Technology) came out a little later and I believe had a hard disk fitted as standard. There were many clones of course, and some of these used the 8086 CPU. The later AT (about 1984?) went to the 80286 processor with its full 16-bit data lines.

I have a Pentium system loaded with WWW browsers etc., but I still have an old Tandon XT clone that I use for simple word processing, accounts, and so on. It has MDA video and I run it with an original green-phosphor IBM monitor. For hours working on documents, I still believe that today's Super-VGA color displays can't hold a candle to that old mono system for clarity.

It has only a 20MB hard disk (remember when they were commonly called Winchesters? [Linked Image]), yet with word processor, accounts software, SuperCalc, Turbo Pascal, assembler/debugger, and a whole load of other things it still has only half of the disk in use most of the time.

The installation routine of some modern software wouldn't even load into that space. [Linked Image]