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Gem PLENUM Organ - Eprom files

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  • Gem PLENUM Organ - Eprom files

    Hello. Here is the EPROM files of the GEM PLENUM Organ I've repaired last year. I took the opportunity to read eprom out from the boards.
    Attached Files

  • #2
    Thank you. I own such a GEM Plenum. No Eprom problems at this stage but very handy to have. I notice though that some of your Eprom versions differ from mine. I think their sounds must have been updated over time.
    But thank you.

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    • #3
      Hello ; I have no idea about what concerns the eprom version differences. Be aware that in some cases, the hardware had to suit the software. I found on each slave boards an additionnal EPROM that was not on the schematics (the 1rst slave board version had an embeded software processor (so with no extra eprom)).
      The issue of the GEM I fixed up was a battery salt melt, which caused dammaged copper tracks on the processor board .

      Eprom are said to be about 40 years storage with any problem............. 😎 but yes better to have the files "in case of failure"

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      • #4
        Hi,
        Nice to know.
        I didn't understand in the first place why GEM had its own CPU with embedded software. Wouldn't it have been cheaper in that time to just take a regular processor and an (E)Prom?

        But this means that you probably could read out that eprom too ? But then it would become possible to disassemble the code that 's in it and then rebuild it as a replacement for the embedded one.
        Anyhow, this would have been an option but I've found in the meantime the OEM version of this CPU so my technical problems are solved at this moment.

        But always nice to share thoughts with someone who owns/worked on the same instrument.

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        • #5
          Hi back
          Unfortunately, I'm not able to read 8051-2 embedded eprom... I just can read standard EPROM with a reader-programmator. I've always design 8032 boards with external ROM. . I think the reason why the program had moved to an external eprom is because the size stored in the EPROM (16K for an 27128) is bigger than the embedded version (8K for the 8052).

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          • #6
            Strange, according to the diagrams I have, the 10711 GEM consists of 128Kb (=16kB) Eprom.

            Click image for larger version

Name:	10711 GEM.png
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ID:	790929

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            • #7
              I have these shcematics and I've never understood what was this enigmatic sheet "masked cpu emulator" ?!

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