PDA

View Full Version : Another Z80 SBC running CP/M



Chuck(G)
August 16th, 2011, 08:59 AM
For those of the perfboard persuasion, this Z80 computer (http://hackaday.com/2011/08/16/easy-to-build-z80-single-board-computer/) on Hackaday might prove interesting.

http://kaput.retroarchive.org/Z80SBC/z80sbc.jpg

Eudimorphodon
August 16th, 2011, 03:20 PM
I'm impressed how low the parts count is on that, considering it's not using any microcontrollers/CPLDs/FPGAs/etc. I've been optimistically pondering trying to make a PET-on-Perfboard as a computer project, which I think could be close to that sparse except for the memory-mapped video display circuitry. (I'm sure these days there must be a low-parts-count solution to that I don't know about. I know it's relatively trivial to generate NTSC or VGA with any number of microcontrollers but the host interface is generally byte-at-a-time, not DMA.)

RickNel
October 12th, 2011, 07:29 PM
Nice schematics, too, at the maker's site. Plus earlier 8080 versions cobbled together from scrap.

Two 8080 versions are built on a 50-pin bus. Is that the maker's original, or some long-lost standard?

Later Z80 version has IDE, but without spare I/O ports it's limited to floppy-swapping for any external I/O.

Rick

glitch
October 12th, 2011, 07:41 PM
Nice schematics, too, at the maker's site. Plus earlier 8080 versions cobbled together from scrap.

Two 8080 versions are built on a 50-pin bus. Is that the maker's original, or some long-lost standard?

Looks like the maker's own. It's definitely within reason to limit yourself to 50 bus lines, especially with modern higher-integration 7400 series devices available. Ohio Scientific used a 48-pin bus carrying three voltages (with two redundant pins each for +5 and GND) and still had at least one spare on the bus!

I've got a good bit of a 50-line bus spec written up, as well as a few boards laid out for it. I'm not sure it's worth the effort/cost to get small-run prototypes made though, with all of the other established (or at least existing) 8-bit bus architectures out there!