32-bit acorn hardware • RISC PC SIMM Slot Problem

I have a RISC PC (running 3.7) with an annoying issue. Anything fitted in SIMM slot 0 (SK6, the one nearest the VRAM) works fine. However, fitting another SIMM in SIMM Slot 1 (SK7) gets the RISC OS banner, with total memory, immediately followed by :
"Error: Internal error: abort on data transfer at &03820E48 {Error number &80000002)"
and that's it.

Remove the SIMM from Slot 1 and everything is fine, boots to the desktop etc. etc.

So, I've cleaned Slot 1 (although the board doesn't seem much affected by any battery rot) with vinegar, IPA and Deoxit in that order, using a toothbrush to get into the socket. The socket and SIMMs look fine (although it's gold plated socket pins and tinned SIMM edges). My next step is to check continuity to the socket (not looking forward to that).

My question is, does the error message give any more precise indication as to where I should be looking ?

SIMM 0 is 32MB, I've tried a few 8MB and 16MB sticks in SIMM 1, all with the same results (not sure the data transfer address is the same each time). I'm assuming it's some kind of DMA type failure as the machine tries to boot off the IDE disk.

Statistics: Posted by cjed — Tue Jan 21, 2025 7:02 pm

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