exxos's Atari, Amiga & retro forum

Hi all,

I've got a late STE with soldered on components, I believe the CA401177 motherboard revision.

I've replaced with Exxos components:
EXXOS PSU STF/M/E/030,
4MB STE RAM SET,
STE DUAL TOS 1.62/2.06 KIT (with TOS162 / TOS206 in English).

Bit of work, but that's all working so far. Floppy games seem to work fine (Frontier and Chaos Engine have been fun).

I'm now attempting to get an UltraSatan Mini working.

Long story short, on any operation, the write operation trashes the drive. Reading seems fine.

The list of mandatory fixes starts to get murky with this board, since the chips are a little different. I'd appreciate some advice on which ones need tackling:

1. PSU - Replaced.
2. SIMMS - Replaced with Exxos.
3. DMA Pullup on databus needed -> Does this still apply on this motherboard? And if so, how do I apply it since the chip is somewhat different?
4. Using original Epson floppy drive - Think it's ok?
5. Can't easily change CPU.
6. Video ghosting fix - applied, but suspect I need better quality caps.
7. Floppy clean - Done.
8. Reset fix - Done.
9. Bus resistors - Not done - open to being done, if it will make an impact (and can identify them on this board revision).

Many thanks to the support of Exxos and those on this forum.

I'd suggest that you look at doing this fix:


Which is on the WDC1772 chip, it helped for my STEs, though I do have a separate DMA controller.

Also the swap to a HC type 68K cpu and replace the databus resistor packs for 2.2k if they haven't already been done, all as per the mandatory fixes page.

kianryan wrote: 11 May 2021 09:25
12) Bus resistors - Not done - open to being done, if it will make an impact (and can identify them on this board revision).

I posted detailed pictures of this board revision : https://www.exxosforum.co.uk/forum/view ... 141#p62876

You will find the resistors P100 to P105 around the CPU

Thanks folks.

Will take all that on board. I've got another bunch of parts on order from Exxos and will give those a try at the weekend.

kianryan wrote: 11 May 2021 16:06 Thanks folks.

Will take all that on board. I've got another bunch of parts on order from Exxos and will give those a try at the weekend.

Just wondering if you followed this up since?