SUMMARY: memory upgrades on IPC and SLC

From: Walter F. Hartheimer (
Date: Mon Jan 20 1992 - 05:02:21 CST

Thanks to all who responded (total of 40!).

Original posting:

        Is it really true that to upgrade factory shipped IPC's and
        SLC's beyond 8 megabytes, the existing memory becomes useless
        $ilicon (sic)? Must they be removed to accomodate only 4MB

        Please share your experiences with me.


        SLC has 4 slots that can only accomodate special 36bit 4mb

        bernards@ECN.NL (Marcel Bernards) says:

                An SLC uses special 36*4 Mbit Simm's (4 parity chips
                and 32 bits data) So an SLC which has 4 slots can
                contain a maximum of 4*4 Mbyte = 16 Mbyte Memory.

        So the only way to upgrade from 8 mb is to add up to two more
        of these special SIMMS for up to 16Mb total.

        IPC has a total of 12 slots divided up 3 banks of 4 slots. It
        uses industry standard PC and MAC compatible 1 and 4 MB SIMM

        Each bank of 4 slots must contain the same type of memory
        (either 4MB or 1MB). Each of the three banks may have either 1
        or 4 MB SIMMS (not mixed within a bank of four slots).

        The 4 MB SIMMS must occupy the lower memory bank addresses.

        So, this is what I am going to do with my two IPC with 8 1MB

                I will buy only 4 4MB SIMMS.

                I will remove the 4 1MB SIMMs from the first bank and
                replace them with 4 4MB SIMMs.

                IPC #1 now has 20 MB.

                I will take 4 1MB SIMMS and place them in the last bank
                of IPC #2.

                IPC #2 now has 12 MB.

        And, this is what I am going to do with my SLC.

                I will buy 2 special 36bit 4MB SIMMS

                I will add 1 SIMM to each SLC

                BOTH SLC's now have 12 MB.

I think this is the lowest cost solution to my problem. And I have
not wasted any $ilicon! However if I were to have extra 1 MB IPC type
SIMM I could use them in an SS1, MAC, or PC clone.

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