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Printer Port

Discussion in 'Electronic Design' started by Wong, May 13, 2004.

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  1. Good I see AEN is in decode too.
    Good work:)
  2. I looked them up (still have copies of the tech ref manuals with listings
    and all diagrams):
    - 8255 was indeed used for keyboard control, shiftreg was LS322, and for
    some other I/O control
    - LPT was not on the mainboard at all! Build on video card or a separate
    card with 2x LS374 1x LS244 1x LS240 1x7405, some glue logic, decoding, a
    LS245 as data bus buffer.

    The manuals were a good investment: they showed how I could add a MUX chip
    in an empty position and quadruple the DRAM size on the board from 256KB max
    to 1MB max. Much cheaper than the memory expansion boards, and the
    conversions I did payed well.

    Arie de Muynck
  3. Great I never ventured to modify the main board, I did modify some Hercules
    graphics cards later on.
    So we could have 4 in a PC.
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