(Topic ID: 272255)

Mix NVRAM and 5101 RAM

By oldschoolbob

3 years ago



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    #1 3 years ago

    I just picked up a Stern MPU 200 that needs some work. First I need to replace the U8 and U13 sockets. I have both NVRAM and some 5101's but I wondered what would happen if I used one 5101 and one NVRAM? Would I still need a battery?

    Thanks

    Bob

    #2 3 years ago

    Yes you would still need a battery for the 5101. I’d be surprised if they’d work together due to the sensitivity of RAM speed on the MPU200 and its need for matched RAM.

    #3 3 years ago

    The way the ram is wired U8 is the upper nibble of each byte (d4-d7) and U13 is the lower nibble of each byte (d0-d3). Depending on where you put the nvram you would have one or the other nibbles backed up.

    As long as the timing worked out it might "work" but 1/2 of the bytes would be random.

    I just use the weebly dual 5101 for mpu200's now. Modern nvram has 100s of the capacity of these old boards rom/ram combined and most of it stays empty in this scenario.

    #4 3 years ago
    Quoted from dothedoo:

    and its need for matched RAM.

    I forgot about that - sorry - maybe not a good idea.

    Thanks for the input.

    Bob

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