New project: ATX motherboard for the Atari ST

[Neurotoxic]

The only thing it's actually missing, is the cartridge port. If someone designs one of those for the ISA slot, it'd be perfect

That was already done for the Milan. I'm not sure if there are any circuit diagrams avaiable for that ISA card?

[Mikerochip]

Interesting. Who would know, I wonder?

I'm in the middle of building one of these ATX motherboards atm. (Just gathering bits).

[gstoll]

The only thing it's actually missing, is the cartridge port. If someone designs one of those for the ISA slot, it'd be perfect

That was already done for the Milan. I'm not sure if there are any circuit diagrams avaiable for that ISA card?

https://github.com/mschwingen/milan/tree/main/RoPoCop

[kodak80]

Interesting. Who would know, I wonder?

I'm in the middle of building one of these ATX motherboards atm. (Just gathering bits).

Also in the middle of building one here as well. Just placed an order for the components I don't have atm.

I am wondering what the inductors L1, L2 and L4 values should be? The schematic and BOM does not show values for these components.

[Mikerochip]

They're not filled, but they are filled in on his photo, so, might be worth giving him a rattle and asking?!

I've just got the PALs and PIC I think to source still. (And I need to figure out some way of writing them still)
Oh, and the W27c020's too.

I would really like to install a precision socket for the 68K processor, but, build a small pcb that has dual wipe contants on it, for the actual 68K processor.

Just means I can easily and quickly swap out the 68k, without damage, for a tf536 or Pistorm etc, but, still have the benefit of using a dual wipe socket.

I was wondering if 2x half size sockets would fit...

https://github.com/mschwingen/milan/tree/main/RoPoCop

Interesting. Not sure what I was expecting, really

I guess, I need to look and see what data lines are connected to the isa socket, and if we can build a dumb 'straight through' cartridge socket.

[kodak80]

x_angel has shared a video showing some progress with the ISA video graphics card working but resetting shortly afterwards.

[youtube=https://www.youtube.com/watch?v=3K0PB-fKflc]

Also he confirmed that L1, L2 and L4 inductors are small ferrite beads. He advises to use small ones.

[Mikerochip]

Excellent, thanks!

Looking at the Cartridge slot, from sporniket STE, since I have it open in front of me, it's got D0-D15, and A1-A14, plus 4 other pins, power and gnd. And the ATX PCB has those data and address lines. Now we just need to possibly patch in 4 other lines, and see about the power.

That would make quite a simple cartridge ISA card easy to make.

He's listed XROM3, XROM4, XUDS and XLDS. I wonder if the ATX UDS and LDS lines are the same...
And then! Where do I get a cartridge slot!!

[DoG]

ROM3 and ROM4 are not routed to anything on the ATX board. But they are available on the GLUE chip (pin 18-17).

[Mikerochip]

Interesting, thanks. So, a handful of patch wires then should sort it. Slightly messy, but! Pretty good. Now, we just need an ISA card

The pin header above the Eiffel PIC is just for the eiffel? Is that right? I don't see pins to use a standard ST keyboard.
(Useful is you have a spare Mega ST etc keyb lying around) Aaand, the rgbtohdmi riser board is still needed, too it looks like.
(I thought the VGA header might have the signals, but, I guess not!)

[Arne]

ROM3 & ROM4 can be generated from /AS, R/W and the upper 8 bit of the address bus

Code: Select all

/ROM3 := /AS & A23 & A22 & A21 & A20 & A19 & /A18 & A17 &  A16 & RW
/ROM4 := /AS & A23 & A22 & A21 & A20 & A19 & /A18 & A17 & /A16 & RW;

or the corresponding ISA bus signals.
But the STGA GAL does not support the ROM port address range:
http://harbaum.org/till/atari/stga/stga.gal

[Mikerochip]

I was thinking of running it without the STGA gal, for just the cartridge port...

[DoG]

The pin header above the Eiffel PIC is just for the eiffel? Is that right? I don't see pins to use a standard ST keyboard.
(Useful is you have a spare Mega ST etc keyb lying around)...

Yes. Master Clear for the PIC, +5V, GND, Mouse Activity LED (GND), Keyboard Activity LED (GND). There is no pins on the board for Mega/TT keyboard. But you can get the Tx/Rx signal on ACIA chip (IC1) pin 6 and 2.

... Aaand, the rgbtohdmi riser board is still needed, too it looks like.
(I thought the VGA header might have the signals, but, I guess not!)

Not a lot of signals there nope.

I would just do a adapter board on the 68000 socket instead of taking up the whole ISA slot if you want a cartridge port. You could also have a place on it for an EPROM that can be activated on or off via a jumper/switch. Or a bigger EPROM for 4 different roms for that matter. This board could also be used in a normal Atari with 68K socket.

[Mikerochip]

Ah! ISA appears to be working! https://www.youtube.com/watch?v=_1TZPUahaW8

I would just do a adapter board on the 68000 socket instead of taking up the whole ISA slot if you want a cartridge port. You could also have a place on it for an EPROM that can be activated on or off via a jumper/switch. Or a bigger EPROM for 4 different roms for that matter. This board could also be used in a normal Atari with 68K socket.

Interesting. But the atx board already has a switcher for 2x tos images, 1.4 and 2.6. I imagine that's going to be enough for me!

Finding cartridge ports will be the next biggest problem.

I don't actually need a cartridge port, I would just like one, is all

I bought a cartridge RTC and, well, it'd be a shame not to use it...

[kodak80]

ISA video now shown as working and stable:

https://www.youtube.com/watch?v=_1TZPUahaW8

RDY signal needs separating from GLUE-DMA by cutting track between DMA to IC12 (GAL) so RDY becomes separate RDY2 signal/track between IC12 and ISA slot.

[TheNameOfTheGame]

Fantastic!

[Atari030]

Troed's Battery backed clock idea should work nice with this too.

[Arne]

I would just do a adapter board on the 68000 socket instead of taking up the whole ISA slot if you want a cartridge port.

That's what I thought, too. But the schematic has even more quirks: why generate -12V with a TL497 when the ATX PSU delivers -12V on pin 11 (14 for 24pin connector). And: why use 1488/1489 when there is a simpler, cheaper MAX232? I don't get it!

[stormy]

I would just do a adapter board on the 68000 socket instead of taking up the whole ISA slot if you want a cartridge port.

That's what I thought, too. But the schematic has even more quirks: why generate -12V with a TL497 when the ATX PSU delivers -12V on pin 11 (14 for 24pin connector). And: why use 1488/1489 when there is a simpler, cheaper MAX232? I don't get it!

If you read his website he does explain that these are his first projects and therefore is a beginner, although he has large projects, perhaps these are just gaps in his knowledge.

[sporniket]

for the 1488/1489, it means reusing chips from the donor board I guess ?

[DoG]

Interesting. But the atx board already has a switcher for 2x tos images, 1.4 and 2.6. I imagine that's going to be enough for me!

I was thinking of those cart that only has an eprom on it and nothing else. Not tos roms. Then you can make it internally. But, probably not needed any way.

[Mikerochip]

How .... do I make my own TOS roms?

Join 2 roms, byte swap, then split in 2?

[stormy]

How .... do I make my own TOS roms?

Join 2 roms, byte swap, then split in 2?

Some forum posts with good info for you:
viewtopic.php?f=15&t=23459
https://exxosforum.co.uk/forum/viewtopi ... 37&p=38447

And some of my own personal notes:

About TOS burning EPROMS/EEPROMS:
Atari STFM:
6 ROM
EPROMs needed: 27C256 x6 (200 or less speed. 150 recommended).
Be sure they are erased or erase them using an UV Eprom eraser (40 min.).

Using Flash ROMs is the same but you need 29C256' 32kx8 ATMEL (28pin) FLASH ROMS instead of 27C256 ones. This options is better because flash roms are newer technology.

Atari STe and Mega STe
2 ROMS
EPROMs needed: 27C010 x2 (less than 200 speed. 120-150 recommended)
27C1000, or with some more hassle with 27C010.27C1001
Or EEPROMS: W27C010
----------------------------------------------
Byte swapping:
dd conv=swab if=source.img of=dest.img
---------------------------------------------

PPutniks ROMSPLIT.PRG:
https://atari.8bitchip.info/astopensw.php
Badwolf's Python script for rom splitting:
https://github.com/dh219/Hi-Lo-Byte-Split
Another rom splitter:
https://github.com/freem/romwak

[Mikerochip]

Thanks!

It's for this ATX board though, specifically, I'd like to know about!

It's got 2x SST 39SF020 (256K) roms, and supports 2 TOS images.
(I wonder if I can use one 512K rom, too)

ROMWak actually looks like it'll do what I want: I'm guessing I just join 2 files, byte swap, then split on the high/low bytes

So,

Code: Select all

romwak /c TOS1.img TOS2.img combined.img

romwak /f combined.img swapped.img

romwak /b swapped.img Lo.img Hi.img

Which, I think, should give me two images ready to burn.

I'm guessing, too, I'll have to pad the 192K TOS images to 256K first, before I join?

Code: Select all

romwak /p TOS1.img TOS1.256K.img 256 0

romwak /p TOS2.img TOS2.256K.img 256 0

[Mikerochip]

I would like to be able to try out different sets:
TOS 1.4 / 2.6
but also MagiC / EmuTOS

[Mikerochip]

Anyone else, besides myself and Kodak80 building some of these?