DEC 3000 model 400 memory

Cody Swanson lists at
Wed Oct 5 22:26:59 CDT 2016

> Assuming this DEC 3000 is the model with the memory daughter boards
> populated with endless rows of (expensive and hard to find) proprietary
> 100 pin SIMMs,yes I have some extra memory and daughter boards.
> Though wikipedia tells me that the 400 model only has two such daughter
> boards, for a total of 8 sticks.

Yes, it does have the proprietary unobtainium ram which is why I came to cctalk. :-) It has 4 long daughter boards, each with two rows of two modules. I was lucky enough to get the manuals with the system. The manuals state that the bottom rows of slots combine to form memory bank 1 and the top rows combine to form bank two. The memory test was failing after a considerable amount of time with an ECC error so I took a gamble and removed the memory from bank 2 (8x100 pin dimms) and now the machine boots to OpenVMS and appears to be stable. This has reduced the total memory to 32MB which I'd like to at least double. I gather these systems can hold up to 512MB. 

> For comparison, inside my 3000 700:

Yours looks exactly like what the layout of my 400 looks like except I have a framebuffer card.
> A couple of fully populated daughter boards:
> I have to grab them from the garage, but I'm pretty sure I have a couple
> fully populated daughter boards ready to go, though I don't remember the
> capacty of the sticks that are in there.  I do remember, that the way the
> SIMMs are banked is counter-intuitive, so be sure to read the
> docs as you swap memory round.
> Anyway, I'm happy to send them to you for testing.  If they solve your problem,
>  we can work something out.

Excellent, thank you. I will mail you off-list. 

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