exxos's Atari, Amiga & retro forum

bfollowell wrote: 16 May 2021 21:52 Sooooo, kind of like MyTek's Atari 1088XEL design for the 8-bits?

More like X_Angel's own Atari ITX (8-bit) project, which he did years ago:

You're probably right.

MyTek's design incorporates many of the upgrades for the 8-bit line, whereas, with the exception of dual Pokeys, I think X_Angel's design is pretty much a stock 8-bit redesign.

From the looks of things, this ST in ATX format looks similar; not a lot of upgrades, just a motherboard redesign.

Personally, I'd be more interested if it were an STe in ATX format, but it's still a pretty cool project. I look forward to seeing how it progresses and where it goes.

Hello to everyone :)

I wouldn't say Atari ITX is stock. You have stereo Pokey, built-in SIO2SD, AKI interface and the board is designed for simple memory upgrade (130XE or 320k or 1MB). I will upload expansion board files on my site.

Also Atari ST ATX has some upgrades: Eiffel interface, 4MB memory, TOS switch, IDE interface, STGA1040 interface and DMA fix (newest version of mobo).

bfollowell wrote: 01 Jun 2021 14:38 Personally, I'd be more interested if it were an STe in ATX format,

I second that idea. Would be cool to have a new motherboard for the STE, and ATX with the ISA slot sounds cool.

Cyprian wrote: 01 Aug 2022 11:26

bfollowell wrote: 01 Jun 2021 14:38 Personally, I'd be more interested if it were an STe in ATX format,

I second that idea. Would be cool to have a new motherboard for the STE, and ATX with the ISA slot sounds cool.

I believe that ATX is a little bit too tight for the STe for placing components, especially when keeping the pal/ntsc encoder circuit, if the goal is to salvage a unit that have dead motherboard but still good components. And if one talks about redesign, I would add a DIP-64 socket to plug extensions.

With ditching the pal/ntsc encoder, replacing passive with hand-solderable cms (1206) and keeping other original component, I believe that it may be possible to reach B4-sized motherboard.

Anyway, anybody can start from my conversion of the STe motherboard into Kicad (shameless self promotion :twisted: ), clear the pcb file and start designing.

edit: don't forget to apply the mandatory fixes !! :D

sporniket wrote: 01 Aug 2022 11:49 I believe that ATX is a little bit too tight for the STe for placing components

How much stuff could be, in theory, offloaded to an ISA format card to give more working space?

Would be quite amusing to have an STE with the card in and and STM with it out. :lol:

BW

Badwolf wrote: 03 Aug 2022 10:16

sporniket wrote: 01 Aug 2022 11:49 I believe that ATX is a little bit too tight for the STe for placing components

How much stuff could be, in theory, offloaded to an ISA format card to give more working space?

Would be quite amusing to have an STE with the card in and and STM with it out. :lol:

BW

Tough question, the STe does not reuse the chipset of the ST. At one point I had theorized a "ReST(e) In Pieces" (pun obviously intended :twisted: ) with a core made of the DIP64 port + MCU + Shifter, DMA, RAM and some other pieces, the rest being pluggable extension. I had drafted the following diagram, with the green boxes being double rows of pin headers :


But there was no intention to implement a standard like ISA. Each interface would have the relevant part of databus (full width, lower byte, upper byte), relevant address lines and other control signal. The YM2149 is troubling because it is used for sound generation and its set of GPIO is used to implement the parallel port.

Going back to the ATX form factor, it could be more reachable by borrowing some space-saving ideas implemented on the H5 : replace the 4 SIMM32 by one SIMM-72, replace the RS-232 circuitry (lots of chips) for a modern all-in-one package chip. Use a DB9 instead of DB25 for the RS-232 port. Going down to 0805 size for passives, with a compact placement (forget references neatly placed beside each component on the silkscreen). Use plcc ROMS (with the benefit of having dual TOS). For standard 74xxx, 555/556 etc, use cms packages.

If you're going the STE route, the "source" of chips is even worse than the ST. You're at FPGA cores basically. Then by the time you bolted on various addons.. You're at the suska anyway.

We are moving to the STE FPGA cores for the H5. But we are building addons from the ground up as most ST addons are a bit hacky and tend to not work right. Take netusbee or PP IDE interface etc. All have many known issues / bugs. It's why we built TRUDIE,

Anyway. Wasn't trying to derail :)

exxos wrote: 03 Aug 2022 18:21 If you're going the STE route, the "source" of chips is even worse than the ST.

they should be available in B&C and Best Electronics