exxos's Atari, Amiga & retro forum

Hi folks,
I'm trying to upgrade 1040st C070523-001 Rev.C 6-chip to 2.06 TOS but facing problems. I'm experienced in electronics and expected it to go straight forward, however can't get board to boot with new chips.
Here is what I did.
1. 1040st is with TOS 1.00 from factory. It also has some interesting daughter board in HI2 EPROM socket. I don't know the purpose of this, but it also boots without it with factory chip straight in the socket.
2. I've already upgraded to HxC, downloaded the atari split program and 2.06US, 2.06UK, 1.04US TOS images.
3. I moved files with "floimg94". There is probably a better way to do this nowadays, but it seems to work.
4. moved extracted files back and burnt on ST M27C256B-10F1. (EPROMs are fine and programmer too, I'm using it a lot).
5. I populated chips in the order on the photo, but none of TOS images worked.

What am I missing?
Is there a jumper or some other rework that I'm missing?
Can someone please share guaranteed to work binaries?
Thank you!

Not sure what the board is unless it's parts of a 206 decoder. You can only use up to TOS104 on a stock ST anyway.

The adapter looks like a Realtime clock adapter and would only be needed if you want the clock to keep running when the computer is turned off. You would need the software to update the date/time into/from it as well.

As noted, TOS 2.06 boots differently and without additional hardware modifications you are limited to TOS 1.04.