I have a '4A in a box upstairs.

Post #434,825 by static 6/26/20 6:05:10 AM 6/26/20 6:05:10 AM Reply	I have a '4A in a box upstairs. I also have a hobbyist Z80 dev board somewhere (from outfit in Melbourne called Talking Electronics). I used to know how to hand-assemble Z80 code... This was the sort of thing that predated the Arduino by several decades but attempted to teach much the same thing. Wade.
Post #434,845 by Another Scott 6/27/20 12:26:46 AM 6/27/20 12:26:46 AM Reply	My grad school prof had an S-100 bus computer... (This was in the mid-80s.) He often talked like he was eventually going get back to it, but I doubt that he ever did. https://en.wikipedia.org/wiki/S-100_bus He managed to get a few HP Integral PCs for his lab. Neat machines, but ungodly expensive at the time (~ $4000, IIRC). Cheers, Scott.
Post #434,846 by Andrew Grygus 6/27/20 2:01:48 AM 6/27/20 2:01:48 AM Reply	Yes, I still have my S100 machine . . . . . taking up space in the garage. Mine was an 8/16 (bits, that is).
Post #434,848 by crazy 6/27/20 7:30:52 AM 6/27/20 7:30:52 AM Reply	So did I Multiuser turbodos which ran cp/m programs. Each s100 bus board drove a single Televideo 910 terminal over serial line. Single 20mb Minnie Winnie hard disk that everyone shares. Ran wordstar, multiplan, and dbase, as well as a variety of language compilers. My simple favorite was pilot. Multiplan had linked spreadsheets 10 years before lotus 123. https://en.m.wikipedia.org/wiki/PILOT
Post #434,886 by a6l6e6x 6/28/20 11:45:36 PM 6/28/20 11:45:36 PM Reply	I built one in part from scratch. Well at least the control panel and CPU board. That included laying out and etching the circuit cards and soldering on chip sockets. The CPU board had Z-80 processor and the EPROM with a "borrowed" 4 KB BASIC interpreter and what is in effect a BIOS. As I recall, besides the S-100 board which has nothing but connectors, I bought an 8 KB memory card and a display card which attached to a TV. The control board had umpteen switches for setting up addresses and loading data into memory. It was possible to step through one CPU instruction at a time. Also, I had circuitry to write and read data to an audio tape recorder. Biggest problem was it was extremely noisy RF wise. You could not watch a TV anywhere in the house. I bought a TR-80 and retired the S-100. But, I even modified the TRS-80 so it could display lower case characters. Alex "There is a cult of ignorance in the United States, and there has always been. The strain of anti-intellectualism has been a constant thread winding its way through our political and cultural life, nurtured by the false notion that democracy means that "my ignorance is just as good as your knowledge." -- Isaac Asimov
Post #434,896 by crazy 6/29/20 8:19:14 AM 6/29/20 8:19:14 AM Reply	You win Hell, you beat Mel

Welcome to IWETHEY!