I bet your z80 didn't do this...

[JimS]

That does look like a fun project...
Back in the Elder Days, i.e. before the Z80 was retro, I built a homebrew Z80 computer. Mostly I used magazine plans, but pretty much dropped the project once I got my Atari 800. Fun while it lasted though. ;-)

[JimS]

The Exidy Sorcerer used a Z-80. It also used  the plastic shells of 8-track tape carts to hold it's ROM carts.
I got my Z80 chip off a fried card from a printer at work.. a nice "mil-spec" ;-) ceramic package rated at a blazing 4mHz!

[JimS]

InTheSand wrote:

JimS wrote:
Back in the Elder Days, i.e. before the Z80 was retro, I built a homebrew Z80 computer.

Ah, well hello from another former "homebrewer"! I have two Z80-based home systems, one cannibalised from an ancient multi-user CP/M system and the other based on the innards of a 3.5" RS232-interfaced floppy drive (briefly on the market in the UK in the 1990s).

Hi, fellow former-homebrewer.

My system was built from some magazine articles in Kilobaud (the CPU, RAM, and front panel) There was a 64x16 text display, memory mapped, built from a Byte article, and altered  from the original 32x16. An EPROM card, and parallel keyboard port were my own designs. I also modded the original 4K RAM design from the Kilobaud article into 16K by changing the 2102 RAMS to 2114s.

The original Kilobaud article was written by a guy who went on to become a space shuttle astronaut, which I always thought was cool. :-)

At the time, I worked for Burroughs, and could get junked parts. I had a whole bunch of wire-wrapped boards pulled from failing mainframes. I unwired several of these, and built my boards on them. I was able to swap for a compatible backplane that held these cards. Some surplus DEC paddle switches (probably from a PDP?) made the front panel. It kinda reminds me of the pictures of the Amiga Lorraine prototype, much simpler though.

Anyway, it was a fun project, even if it never went much further. After I bought the Atari, I was too busy to write an OS for the homebrew. Still have it though. :-)

I don't know about other cores for the minimig.. there's a 68000 (a real one) on there that would have to be shut down for some stuff... Hmmm I wonder if you could make it into an Atari ST/Falcon, or a classic Mac? Or would the PPC Macs be "classic", and the 68K macs be "classic classics"?

-Jim

[JimS]

The fun thing about the display was that it used a TV camera sync generator for it's basic timing. The dot clock and H & V blanking were independent and adjustable. So I could adjust it to fit the monitor or the TV. Even record it properly on the VCR.... no genlock though. :-)

The next plan was to put some routines in EPROM... but thats where it ended. Now and then I think about using that eeprom kickstart hack to burn a ROM for it. :-)

On the minimig, I believe there already are cores for many of the old 8-bit machines free for the asking on places like opencores.org or fpgaarcade. I don't see why someone couldn't port one of those to minimig. Personally, I think a 'hacker friendly' approach to minimig would be to replicate Dennis' 68000 and I/O boards and attach them to a stock Spartan III dev board. Xilinx has a dev board for $149 that ought to be suitable. Still, we'll have to see what happens with minimig, if someone puts out a kit or what..

-Jim