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

[LoadWB]

I used several different CP/M language compilers, like Small C, Pascal, and COBOL on my 128.  I had a highly customized boot disk and am planning to get back involved with one of the newer Z80-specific Kernals (IIRC, the original CP/M+ v3 is actually 8080.)

[InTheSand]

Interesting to know!

And you're right about the 8080 - all original CP/M versions were designed to run on that and don't use the additional features the Z80 provides...

 - Ali

P.S. I'm glad Zilog changed the assembly language opcodes when the Z80 was produced... 8080 assembler is just plain nasty! Familiar-ish, but just... wrong....!!!

[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

[InTheSand]

Sounds like your homebrew project was a good one! Nice to have a real display rather than slow and boring RS232 terminals or emulators to display any output!

I created the rudimentary parts of a basic OS for my machines - usual BIOS/BDOS-type functionality, plus a command interpreter with monitor-like functions (dump/fill areas of RAM, show/change registers, upload code, etc) but haven't done anything with it for years.

As for MiniMig cores... If the 68K can be shunted out of the way, the FPGA core itself is probably more than capable of emulating an entire basic 8-bitter like the Spectrum... Or perhaps the 68000 could be used to run the Z80 code with the FPGA emulating the rest of the hardware? I guess there'd then be synchronisation issues though... But I'm sure someone will have a go!

 - Ali

[Karlos]

InTheSand wrote:
P.S. @Karlos: nice pic! :-)

Cheers. Pity it wasn't a genuine Zilog though :-(

[InTheSand]

Yeah, bloomin' clone rubbish!!!  :-)

 - Ali

[Agafaster]

Mmmm Z80! top CPU!

I toyed with the idea of a homebrew computer based on one of those. ever since my GCSE Electronics project in 1988!
(I had to do something less ambitious - an Audio ADA for my speccy - didnt work!)
I am now going to resurrect the idea (as far as possible with 3 kids, a wife :roll:, two amigas to play with, and sorting the wimmins' problems with the house PC!)
I kinda got stuck on getting the RAM interface between CPU and Video sorted out (trying to prevent these from clashing), but I have ideas there...

[koaftder]

People can say what they want about Amiga, but the reality is that the comunity is chock full of real hackers.

[Karlos]

Pity the homebrew guys don't use one of these... you can get a linear 16MB address space on those and they are z80 code compatible.

I was toying with the idea of using a Z180 as an expansion/upgrade experiment for a spectrum. It has a builtin paged MMU for up to 1MB of external memory and other enhancements.

Only problem is, no time :-(

[Agafaster]

Karlos wrote:
Pity the homebrew guys don't use one of these... you can get a linear 16MB address space on those and they are z80 code compatible.

I saw that ! (I've been furtling too ;-) )
kinda nice - not having to fart around with paging protocols and memory maps!

I was toying with the idea of using a Z180 as an expansion/upgrade experiment for a spectrum. It has a builtin paged MMU for up to 1MB of external memory and other enhancements.

I've had those what if... moments meself.

can you imagine Centipede on a 50MHz speccy ? :-o :lol: :crazy:

Only problem is, no time :-(

me neither :shrug:

[bhoggett]

I used to program a Z8 in assembler for an embedded security surveillance device many years ago, and I remember it was fun - though perhaps not the most productive way of doing things, particularly since the devices were meant to be small cost effective alternatives to a more complex model we were selling. I remember that afterwards when people saw that in my resume they kept saying "You mean a Z80, don't you?".   :lol:

[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

[CLS2086]

Gaps, I'm the only fan of these :



http://vg5k.free.fr/index.php?lng=EN

The missing link between Odysse2/Videopac+ Basic module and the MSX  :-)

[kvasir]

I thought the game boy color also used a z80, but its been awhile since I looked into it.

[InTheSand]

The eZ80 does look like a nice CPU to base a project on... As Karlos says though, time is always a problem!

If this project goes anywhere, I'd be very interested in getting one if they ever became available for sale... A 40MHz 1Mb Speccy-ish machine sounds fun!!!

@kvasir - yes, the original Gameboy and the colour version use Z80 derivatives but they're not 100% compatible due to some differences in the instruction set.

 - Ali

[rzookol]

Have You seen this:

http://en.wikipedia.org/wiki/SymbOS