New project: ATX motherboard for the Atari ST

[Atari030]

I just dropped a ton of SMD resistors in tonight. Not many more to go. I think I'm going cross eyed.

[frank.lukas]

... back to Mega ST status :P

Mega ST Clock with RP5C15 without PAL/GAL from @czietz ...

You can buy the chip on ebay.

https://forum.atari-home.de/index.php/t ... #msg241952

TOS-Uhrenmodul_klein.jpg

No need from a driver you need only TOS 1.02 or greater or EmuTOS ...

[czietz]

Just to be clear: The design itself is not mine. I drew the schematic based on photos of the "Mega Clock" that were posted in the forum.atari-home.de thread. Frank made PCBs based on my schematic; so we know it works.

PS: There is a version of the schematic with less liquid spills in the forum.atari-home.de thread, too

[Mikerochip]

All those signals are available from the 68000 socket? Except 32mhz... So, a pcb should be easy enough to make. I think

[frank.lukas]

32Khz not Mhz ...

The Clock Modul has his place under a TOS ROM with two wires to the CPU (AS and VMA) ...


... but with it on the circuit board like the Mega ST would be nice as well as a ROMPORT. The ROMPORT buffer can sit near the STGA ISA slot.

[Mikerochip]

Why not under the CPU, out of curosity?

As you say, it could be combined with a cartridge port, and maybe blitter too??

[Atari030]

Troed's clock should work, should it not? It'll need a driver but it won't need a new PCB.

Got the bulk of SMD and through hole components in last night, working on sockets now. 1am before I looked at my watch. Finding a 64pin skt is a PITA. Most other stuff is available locally.

[Mikerochip]

I used round/precision pin strips. It's damn near impossible to find dual wipe 64 pin 2.54 / 23mm sockets
I built 3x boards together.
"I'll just solder the sockets ..." 8hrs and 2,200 odd solder points later, I was done!

[Atari030]

LOL, I know how that feels. Picked up a few more bits and pieces from Altronics today but those 64 pin and 32 pic sockets are an a$$ to find locally.

[Mikerochip]

Not just locally. Everywhere. It's really hard to find them, in 2.54mm pitch. Chinese suppliers have mountains of them, but they're all too narrow, and 1.77mm pitch. He said, looking at the "I swear they're 2.54mm" batch here

[kodak80]

Got my 3rd ATX board working over the weekend. I had a dead Glue chip and Yamaha chip. Once these were replaced, the board worked. This board has the CPU SIL resistors socket to allow me to test my CPU expansion adapter. I now need to re-test the CPU expansion adapter board again.

I did manage to get round to testing my ATX ISA Cartridge adapter board and this worked with my Cubase dongle. I ran 2 wires from the underside of the Glue chip, pins 17 and 18 to the ISA board.

IMG_8174 - Copy.JPG

IMG_8175 - Copy.JPG

Also, my parallel corrector adapter worked as I was able to print to an old dot matrix printer from 1st Word.

Screenshot 2022-09-25 094428.jpg

This adapter also corrects the 26 pin serial header pinout. I have not found a way to test serial yet to confirm.

Here is the 26 pin IDC fix PCB gerber:

26 pin Header Fix gerber 2.54mm.zip

I have also stopped using HDDriver for my IDE disk as this was proving too unreliable in the ATX system. I am now using PPetari's hard disk driver (purchased a few years ago) which works fine in the ATX system and I can also mount the CF card in my windows PC to copy files across to the drives.

[Mikerochip]

OUTSTANDING!!

[Cyprian]

well done

[Atari030]

Love your work, mate.

[kodak80]

Diag cart also now tested and working with the ATX ISA Cart adapter

IMG_8186 - Copy.jpg

IMG_8189 - Copy.jpg

IMG_8188 - Copy.jpg

And MV16 sound cart also connected and tested with Monkey Island 2 ScummST sound card set to MV16...worlds first Atari ST ISA sound card?

IMG_8190 - Copy.jpg

[Atari030]

Uber cool. Nice one.

[alexh]

Very nice work. I'd really like one.

[Badwolf]

Yes, fantastic stuff!

[Mikerochip]

Given that the pinout for the Serial and Parallel, are 'wrong', has anyone checked if the pinout for the ACSI pin header port is 'wrong' as well?

With Kodak80's working ROM port, only thing we're still "missing" is a blitter PCB
( *cough* any maybe a low profile ROM port too )

I take it, because of the increased colour palette, the STE combined MCU + blitter is incompatible?
(ie C302183 / MM9200C0C)

I'm guessing C101643 / I60611 / MM9092V should be fine though?


Actually, just checking it, the riser pcb for the RGBtoHDMI socket doesn't seem to fit either.
But that's a job for tomorrow

[kodak80]

My current tested and working ISA cartridge adapter has the cartridge connector flush with the ATX case ISA slots, so whilst it will work with cartridges that are not in a case, you would not be able to use any that are in cases. The current PCB gerbers are here for anyone wanting to get some made:

cart-routed.png

Cart Adapter-routed_2022-09-08.zip

Here is the next version I am working on which moves the cartridge port outside the ATX case and has allowed for cartridges that are cased to be inserted. I had to redesign this one in KiCad as the size is not allowed in te free version of Eagle:

Cart v1.1.jpg

[stormy]

Could you guys advise on where you can buy an ISA socket/slot for the motherboard? Are there any sellers on ebay? Cheers.

[kodak80]

Could you guys advise on where you can buy an ISA socket/slot for the motherboard? Are there any sellers on ebay? Cheers.

These are the ones I purchased:
https://www.aliexpress.com/item/1005001414139438.html

[Mikerochip]

Could you guys advise on where you can buy an ISA socket/slot for the motherboard? Are there any sellers on ebay? Cheers.

I bought Mouser parts: 571-2-5530843-7 and 571-7-5530843-0

[stormy]

Thx guys

[DoG]

Given that the pinout for the Serial and Parallel, are 'wrong', has anyone checked if the pinout for the ACSI pin header port is 'wrong' as well?

The pin numbers are correct on all of them. However. If you are using a ready made IDC26 to parallel port DB25 that exist on the market it doesn't work. That is since the DB25 has it numbering top row first and then the bottom, so press fitting a ribbon cable makes it "wrong" from IDC numbering so to speak. However, kodak80 adapter fixes that.

The same logic goes for ACSI I guess. But the pinout/numbers is right on the IDC on the MicroATX board.