Specifically, I'd like to find out which version of the IBM PC family
    first included a parallel port.  As far as I can tell, this was the
    IBM 5170 PC/AT, released in 1984.

In early PCs, the parallel port tended to be included on the "monochrome
display adaptors", including the original IBM/PC text-only display, and
later the ubiquitous "Hercules compatible MDA" cards that appeared in most
clones.  I don't think that my old PC/AT clone has a separate (motherboard)
parallel port; it was still on the display adaptor.  I think that about the
time that IDE was introduced (and color monitors starting coming down in
price), the parallel port moved from the display adator to the
"multifunction IO card" (IDE/Floppy/parallel/serial/game), and still later
that they showed up on "most" motherboards.

BillW

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