exxos's Atari, Amiga & retro forum

Since you have installed sockets for the ROM chips you might want to consider getting a SidecarTridge TOS Emulator: https://sidecartridge.com/products/side ... -atari-st/

This makes it a lot easier to switch between different TOS versions or even to use EmuTOS.

don_apple wrote: 10 Mar 2025 15:20 Since you have installed sockets for the ROM chips you might want to consider getting a SidecarTridge TOS Emulator: https://sidecartridge.com/products/side ... -atari-st/

This makes it a lot easier to switch between different TOS versions or even to use EmuTOS.

No need for that, the TwiSTEr has an onboard FlashROM that allows four different TOS versions to be switched by software, besides the one on the main board to be used which can be enabled using a jumper:
There's an advantage to using the TwiSTEr's onboard ROM, though: it runs at the same speed as the processor. Using the mainboard ROM's would slow down the 020. Overall, this is a pretty nifty kit!

Ah, OK. Wasn't aware that this is already included on the TwiSTEr.

Progress with the 68000 CPU: reinstalling the original CPU runs perfectly at 8MHz (but not at 16MHz, for obvious reasons). I was using a 68HC000FN20 sent to me with the TwiSTEr. Matthias recommended trying to clean the contacts, but unless the two CPU's are sitting differently on the socket, I don't think that's the issue. Will try doing it anyway. I think I have another FN20 lying around so I'll try that one as soon as I find it.

Overall, not a big deal, as I'm more likely to run with the 020, as the speed bump is very noticeable, and only revert to the 68000 for games, in which case running in 8MHz will likely be required for compatibility anyway.

Next step is coming up with a permanent solution to deliver power to the CF card, but that's for next week.