MCM66128L20

Alexandre Souza alexandre-listas at e-secure.com.br
Wed Apr 11 09:19:23 CDT 2007


>>That's the first thing that puzzles me. It was my understanding that
>>these were 128Kbit chips, so 18 of them would give you 256K bytes (+
>>parity) of memory. Can you confirm, please, that 18 of them really are 
>>512K
>>> The top chips are stamped MCM66128L20;  the bottom chips have no part 
>>> number.

    Maybe the bottom chips are just EMI filters/pull ups??? :oO

    There are NO possibilities that memory can be piggybacked this way. When 
you piggyback two memory chips, at least ONE of the pins must be routed 
separately. At least this is what logic tells me.

    I never seen a 128K *D*ram chip. SRAM exists. This is something that is 
driving me crazy here, I cannot find any datasheets/pinouts on this part 
number, nor any kind of info. Crazy.

    IF the memory was 16-bit-word, maybe you could be using 256K chips

    What was the replacement part you got?

    Greetings,
    Alexandre 




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