exxos's Atari, Amiga & retro forum

FYI, there is also the similar 68k-MBC board with a 68008 CPU. I unofficially ported EmuTOS to it, it works like a charm. It is able to run any textmode Atari program, provided that it only uses TOS system calls (no direct hardware access).

Is this expected that someone has edited my post above?

BlankVector wrote: 10 Nov 2024 00:18 Is this expected that someone has edited my post above?

Sorry my error and one of the problems of posting using my phone. I edited rather than quoted, but don't worry I have fixed it and it was only because I am an admin that I could do this, normal users can't.

BlankVector wrote: 09 Nov 2024 22:22 FYI, there is also the similar 68k-MBC board with a 68008 CPU. I unofficially ported EmuTOS to it, it works like a charm. It is able to run any textmode Atari program, provided that it only uses TOS system calls (no direct hardware access).

I'd seen that too :)

Nice job porting EmuTOS over :)

rubber_jonnie wrote: 10 Nov 2024 09:26 Sorry my error and one of the problems of posting using my phone...

Nothing beats a good ol' keyboard...

;)

HigashiJun wrote: 10 Nov 2024 10:52

rubber_jonnie wrote: 10 Nov 2024 09:26 Sorry my error and one of the problems of posting using my phone...

Nothing beats a good ol' keyboard...

;)

Indeed!

I have that board as well.
And it can even run at 10Mhz.
You can overclock the Atmel, provided it has the correct firmware on board.
This is described with the article at Hackaday.

As for running with the other Z80, it should work fine if you set the clock frequency to 4Mhz.

I've also made a PCB with this setup, but with all important signals connected to an Edge connector.
This way, extensions can be made to the setup.
I've used the SBC-8085 buss setup for this.

BR/
Guus

guus.assmann wrote: 10 Nov 2024 15:03 I have that board as well.
And it can even run at 10Mhz.
You can overclock the Atmel, provided it has the correct firmware on board.
This is described with the article at Hackaday.

As for running with the other Z80, it should work fine if you set the clock frequency to 4Mhz.

I've also made a PCB with this setup, but with all important signals connected to an Edge connector.
This way, extensions can be made to the setup.
I've used the SBC-8085 buss setup for this.

BR/
Guus

Thanks Guus, I did see over on Hackaday that the CPU I have should work at 4Mhz, but the bottom line is that it doesn't despite the seller on eBay stating that it was tested fine. I guess we'll see when the CMOS CPU arrives in the week.

I guess the bottom line states it needs a CMOS version of the Z80, and I just don't have one, though the CPU supplied with the kit does work just fine in my Spectrum.

It did boot just the once to CP/M which suggests to me that that side is OK, but the CPU isn't. Clock is fine at the CPU and address/data lines look ok BTW.

I did also read about overclocking the Atmel so long as you have the right firmware, but I guess you need a CPU that'll handle it too.

OK, so I got a CMOS Z80 and it still doesn't work.

The boot process works like this: after the reset, the Atmega "feeds" the necessary instructions to the CPU to load the binary into the RAM, then it resets the Z80 CPU and let it run.

What I'm seeing is that when I reset, the BIN file loads from SD card and at the point the Atmega hands over to the Z80, the data lines go from looking normal to some sort of sawtooth type affair and the whole things hangs.

I discovered that my TL866II Pro can test Static ram, and doing that shows data bus errors for the IC, so I now have some replacement memory on the way.

How annoying. I ordered memory from a trusted supplier on eBay (By trusted I mean their parts have always been good) and it's taken 4 days to post them :(

Fingers crossed they'll be here soon, but I really do hope they don't take another 4 days to arrive...