The SIMM Card

    The ALR docs are a bit confusing about the type of RAM that this card requires:

"An interleave in this system requires a minimum of two 36-bit SIMMs (1 row/72-bit wide) containing a total of 64 data bits plus 8 bits of ECC RAM."

    Well, 36-bit SIMMs are parity, not ECC, right?  I found this little tidbit on the Kingston site, which pretty much clears it up.  The board needs parity SIMMs and uses groups of two to create enough spare bits for ECC.  Pretty cunning, really. 

    So the next question we have, is parity really required?   The answer is yes from our testing.  We have tried regular fast page RAM with no success.

   There are two banks on this board, each with 8 SIMM slots.  What this means is that you must have the same size RAM in each bank.  In our testing, we used four 16 Meg SIMMS in bank one, and four 8 Meg SIMMS in bank two.  We also had no problem with 2 SIMM configurations.  We did notice that some 70ns SIMMS won't work in the first two slots.  Seems that if 60ns SIMMS are in the first two, the board will run the rest of them at 60.

Update:  For the heck of it, I tried some PS/2 parity SIMMs out of an RS/6000 I had lying around.  They don't work either.