A4000 RAM problem

[tonyw]

Do you mean that it recognises Chip RAM but not Fast RAM? If the SIMMs are not faulty, it would have to be one of the custom chips, like Ramsey.

ton

[tonyw]

I don't know how the RAM on the CSII is addressed, but the RAM on the mobo is addressed by Ramsey. Ramsey provides the addresses, RAS and CAS lines, so I'd guess that would be the most likely culprit.

tony

Edit: Have you tried swapping the Chip and Fast SIMMs? Just to prove the Fast SIMMs are OK.

[tonyw]

Yes, that's right with the internal/external clocks - they have to be changed for each CPU board.

You can plug in bigger SIMMs (eg 16 or 32 MB), but they will only address 4 MB each. You can use 32 or 36 bit SIMMs too, any parity bits will be ignored.

Did you try swapping the SIMMs into the Chip RAM slot to test them?

tony

[tonyw]

There is one jumper for the Fast RAM - it's J852. According to my book, it's just to the right of the vertical backplane (under the CPU board).
It selects whether you have 1 M or 4 M SIMMs in the Fast RAM slots. Select "256k" for 1 M SIMMs, "1 M" for 4 M SIMMs.

tony