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ROM contents of MC68HC11G5FN1?

Discussion in 'Electronic Design' started by James Meyer, Jun 18, 2005.

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  1. James Meyer

    James Meyer Guest

    The 68HC11G5 has 16K of ROM. Presumably, the ROM was hard coded at the
    factory. I say that because it isn't EPROM or EEPROM, the package is
    windowless, and I can find no information about programming it.

    I'm also assuming that the suffix, FN1, would tell me what the ROM
    contents are but I can find no information about that either. The chip is
    obsolete, I guess.

    The only thing I can think of that may be in the ROM is Motorola's
    BUFFALO monitor. Can someone confirm or deny my suspicion?

  2. bruce varley

    bruce varley Guest

    I run my own OPSYS/dev environment for HC11, but once I had to interface
    with a device incorporating BUFFALO. I added some brief notes on the topic,
    which I can hardly understand myself now, to my reference docs. Here is a
    snippet that you might be able to get something out of, sorry I can't make
    it clearer. Jump to the addresses and see if anything comes back. IIRC, the
    com settings are 96,8,n,1. Good luck

    The Motorola BUFFALO opsys resides in ROM at 0E000H. Generally, devices
    with BUFFALO also have EEPROM at 0B600H. The reset vector points to
    the start of ROM, 0E000. The first 3 instructions in ROM are:

    LDX #100AH
    BRCLR 0,X 1 BUFEXEC ; If PE0 low, go to buffalo start
    JMP 0F600H ; else go to EEPROM start
    BUFEXEC: .............
  3. James Meyer

    James Meyer Guest

    The reason I asked is that all my development hardware is for the
    "normal" 52 pin quad packages and the '11G5 comes in a larger 84 pin package.
    It's got non-multiplexed address and data busses along with some other

    I was trying to avoid getting a new system just for the bigger chip
    unless it had something really neat inside. Otherwise I would have just plugged
    it in and asked it what it was.

  4. Trevor

    Trevor Guest

    FN1 in 'hc11s usually means the package type (PLCC)
    temperature range 0-70C and the '1' means an E clock speed of 1MHz.

    I don't know the contents of the ROM - the 'E' chips that I'm
    familiar with have a 'B' suffix before the FN to indicate Buffalo.


  5. Normally those letters indicate the package type and max
    clock rate.

    Assuming you can control MODA and MODB pins, you can power up in
    bootstrap mode. That allows you to boot-load a "talker" or ROM
    dumper program into RAM, which can show you the entire contents
    of your ROM.

    I don't maintain it any more, but my DB11 'HC11 debugger has the
    ability to do this, and to disassemble the code direct from ROM.
    I never finished the Windows port, but it runs on several *nix's.
    Google for it, or search

    Clifford Heath.
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