Due to some recent interest in the Steem mailing list, I decided to post whatever info I have on the Atari ROM module I own. In the mailing list it was noted that the german magazine c't once had such a module, but I'm not sure whether this is the one or not. I did, however, win it in an auction on ebay.de, so it just might be it. If Matthias Arndt can scan the schematics from the ancient magazine we could confirm it...

The board plugs into the side cartridge slot of the Atari ST. It is not pass-through, i.e. it is the last device you can plug in the cartridge slot chain. The design is very, very simple, as you can see. It holds an EPROM labeled "ROMOS4 v.8.0" but I'm not sure about its contents, as I can't find my STe right now (gee, I really wonder where it went).

There's a small red switch on the side which can be used to turn the board off without removing it from the cartridge slot.

The maximum memory size it can hold is, AFAIK, 128kB, since there's only 128k od address space in the ST memory map. I do guess there's the possibility of bank switching, but you'd need some bank switching software.

The EPROM is, of course, read-only, so the whole thing can only be used to quickly access frequently-used, small programs. I'm not sure if you can autorun its contents, in which case you could run accessories of it, but anyhow. The module does have a booting sector, however, so maybe something could be done with it.

The only way to write onto the EPROM is first erase it (remove the small silver sticker at the middle; expose the chip to UV light for approximately 10 minutes) and then use an EPROM burner.

There's a driver that comes with the module, ROMDSK. However you can make it auto-loadable by injecting it into the first 512 bytes of the file that is to be burned onto the EPROM.

The module's contents, once loaded, are mapperd into the $00FA0000-$00FBFFFF (decimal 16384000 - 16515071) Atari memory area.

That's about it, if you need any more info, lemme know...