It's in French but today I'll learn to read
I can explain now. Great that we've got this page, i hope we'll get the others soon.But even with the doc I did not understand exactly how SW1-1 and SW1-2 worked.
According to that and Fred's book, i can say for sure that i have standard BM45, you have BM45 with upgrade (and someone else may have BM45V).
SIMM banks are arranged as labeled pairs: 0,1,2
In my case, first two SIMM banks (0,1) are limited to give 640k of base memory, in fact they are pre-configured for 2x256k (and 2x64k?) simms, not 2x1M. Only the last bank (2) gives extended memory, it was not an error. There were only 1Mb and 256kb SIMMs available these days, so I can choose between 512Kb and 2048k only.
Our SW1 block action differs.
I couldn't get any EMS with SW1 #1 = ON because it disables last bank (2) on my board.
That's why in this case there wasn't any activity on Z322 input connected to SIMM A9 data line (it's common for all slots, but only 1Mb simm needs that, therefore <=256Kb will be still available in each slot) and got errors when it was enabled (0/0, 0/1 combination) when last bank was unpopulated (2x1, 4x1 config).
On your board, 0-bank is always enabled, SW1 #1 = ON simply enables middle bank (1) and SW1 #2 enables last bank (2). Also, your board doesn't give error for unpopulated banks, and each bank is configured to accept 2x1Mb only (it can't auto-detect 256/1M so they've locked that to 1M and used 2 switches for better purposes, that's why you can't install any 256kb - it thinks that it's 1M). Remember, i've described same situation with 2x64k in the very first bank (0). It only counts to 128k and then hangs - so my first bank is locked to 512k like yours to 2M, only difference is that 256k is electrically closer to 64k than to 1Mb module, so I get picture and you don't get any, because significant lines for 256 are grounded.
You can't install less but maybe more? If you have any 4Mb 30-pins, you could try that in last slot, maybe that's the way to get 13Mb from the manual.
My board doesn't have proper lines for them to work, maybe yours has. Up to now, i haven't understood that 13Mb origin.
I will continue reading other pages and think more.
I hope that only Z322 PAL logics makes that difference, but we have to investigate that more, that's why i need photos of that area and maybe not only the photos.
I am going to make turbo-switch with a help of remaining switches of SW1 block, since we are sure that they're unused.