Indigo2: populating memory banks - Printable Version
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Indigo2: populating memory banks - synthetix - 08-10-2020
It turns out the Indigo2 I recently bought has some damaged memory slots in Bank A (closest to CPU). The machine still works, but two memory banks have the metal tabs missing that hold the memory in the slot. So, they're only being held in by one metal clip on one side.
Seems like the options are 1.) pay to have this repaired or get another motherboard, 2.) move all the memory to banks A and B, or 3.) leave it alone and hope it works reliably.
What's the downside of option 2, populating banks A and B? Is there a performance penalty from doing this?
RE: Indigo2: populating memory banks - Raion - 08-10-2020
You have to populate the banks in order, with 4 SIMMS in each bank. The reason is each SIMM is 16-bits wide, so you need 4 for a 64-bit wide memory bus.
So yeah, desolder/replace is the only proper way.
RE: Indigo2: populating memory banks - synthetix - 08-10-2020
The 4 module requirement makes perfect sense. But why would it matter which bank? If you're populating in 64 bit groups (4 modules), shouldn't it work in any bank as long as you've got 4 modules installed? I would test this myself, but I'm honestly hesitant to mess with anything in there until I have a clear plan.
RE: Indigo2: populating memory banks - Raion - 08-10-2020
Generally my experience has been that you can't skip banks. The system will refuse to boot if you skip. My assumption would be that it's because they're all treated as part of a flat memory map but that would be just a hypothesis from what I know about how hw functions.
RE: Indigo2: populating memory banks - drmadison - 08-10-2020
Pretty sure the machine stops looking for ram once it finds an empty bank.
So if bank A has nothing it, it won't even look at ram in bank B.
RE: Indigo2: populating memory banks - synthetix - 08-10-2020
Ah, okay. Got it. I'll just leave it alone for now. At least it's still working!
RE: Indigo2: populating memory banks - 02girl - 08-11-2020
I run my Indy with board 0 empty, but that's the Indy.
RE: Indigo2: populating memory banks - synthetix - 08-13-2020
Just an update on this. I found a possible replacement motherboard, but I saw a photo and the layout of the board is different from mine. Mine is the IP28 195MHz R10K, part number 030-0978-001. The board I'm looking at is the 175MHz R10K version. Does anyone know if it's possible to install the 195MHz CPU into the 175MHz board?
RE: Indigo2: populating memory banks - Raion - 08-13-2020
Should be possible but you might have issues if you're an impact system.
Honestly though I wouldn't replace the motherboard over this. while it is tedious anybody with a hot air gun should be able to do this for you so I would ask around either here or on other retrocomputing boards for somebody to do this. To compare this is a little bit like throwing away an entire car because a radiator mount broke.
RE: Indigo2: populating memory banks - synthetix - 08-13-2020
I agree it's definitely worth repairing vs replacing, but the question comes down to cost. If I can find a replacement for less than it would cost (assuming I can't find a generous person willing to donate their time), then there you go.
I am a software developer, and I bought the machine to write 3D graphics demos for (I already wrote some for my O2), so I could share my graphics demo binaries in return for repair labor!