Without an ICE-T I have been tracing using a DSLogic Pro on the 16 address channels, and comparing with the F000 disassemble , Atomulator, a generic memeory map and a calculator.
What I basically have is an EPROM with C000 to FFFF ATOS MOS, and a large piece of SRAM taking up the rest of the lower address space.
Tracing it through and it just gets to checking the VIAs before printing the first character of the POST message. And then just loops forever at waiting for &B801 (Data Reg A) to respond. So bearing in mind what is actually at B801 is SRAM can I just fudge it into thinking it has responded? And then pull the data from 8000 and stick down a serial connection?
From my understanding B800 is the optional 6522, and I dont actually want to use it, now I remember reading somewhere these are tied low or high with resisters when not used.
So D1-D3 are tied low with 4k7 resistors.Roland's New ATOM ThreadWhat about the 'mystery' resistors R39/40/41 -> D1/D2/D3
In my Atom-in-PC board I left them out as these resistors are only relevant if there is no 6522 via installed. On the Atom-in-PC the 6522 is always installed so the resistors are not needed. I used this design philosophy with my new Atom design. But now I realize that in this Atom the 6522 might be left out, so yes, it's better to add these resistors
What are D0,D4-D7 are they NC when no 6522 fitted? Thining about it B800-B80F are they are SRAM are probably not initailed so could be any old rubbish in there. According to Atomic Manual they should be set to 0. I am asusming that is true regardless of whether it is fitted or not. It is certianly set to 0 on Atomulator, but assume that is emulating a 6522 anyway.
ATOMIC manual OCR a bit up the creak, will add a screenshot instead
I am assuming as people have built complete ATOMs and GODIL replacements there are probably some other sources I havent come across yet. Explaining this. (I havent tried to work out what the ATOM in FPGA code does!)
Might have to stick the Saleae 8ch only the data line to try to grab what value &B801 is actually set to.