snarkdluG

You can create blank/formatted ST files under floppy menu in Hatari. Otherwise just format with F-Copy or something similar if you already have stuff on it.

Glad to hear it worked out.

If you remove the Shifter chip (large chip in the middle) what does it say on the board? If its for a Mega 2 then all the wires should attach to another board which fit over the MMU. So the ram upgrade has been modified for a ST instead. Look here: https://docs.dev-docs.org/htm/search.php?find=Z-RAM

2 computers without modems needs a null modem cable to be able to talk to each other. It flips some wires in the cable, for example the send is connected to receive in the other end, handshaking, carrie detect and so on.

It' still a DS1307Z just marked on top as a DS1307:

Key caps sold in Germany by RTS I believe. Came with new rubber domes apparently. Called "RTS Tastenkappen / Tasturkappen".

TOS images can be found at http://www.avtandil.narod.ru/tose.html for example. You have to split them though. Use http://atari.8bitchip.info/ROMSPLIT.ZIP

Atari Mania got both the preview version you want and a full version.

Great work!

You can use on board memory with the Marpet if you want to. Usually you disable one or both banks on the board and just use simms in the Marpet simm holder. I'm not sure if it would help in this case since a whole bank is gone. The Marpet board just connect on top of the mmu and the shifter. So if either of those two chips is bad it would not solve it.

US is a hard disk drive replacement. ST and MSA are floppy disc drive images as you know. Use a Gotek or a HxC to replace a floppy disc drive for a more modern usage.

You don't have to, but it's easier. Use a small screwdriver or something similar hard tool. The pry the chip up with the screwdriver in the small slit on opposite end from each other, in the corners. Just pry a little each time. Do it equal amount on each end until it pops out. Don't just pry on one end. Otherwise you can use a plcc extractor like the black ones from ebay.

Should be labeled U56 on the silkscreen on the board next to the socket. Later revisions have surface mount chip soldered to the board. See different STfm revisions here.

You can switch the PSU to test. Even MMU chip can be switched to test if it is socketed.

Open the connectors om the cable and check solderjoints there. Floppy problem seem like another problem. Edit: Sorry. You had already checked The cable. Totally missed that

Pics of different boards can be found at exxos site. You should also check out Atari doc archive.

You can't move the floppy cable. It is attached to the motherboard. You have to desolder it if you want to try that.

In what languages is it available? Only English?

YAART - (Yet Another Atari RAM Test)