It's wired as DTE, but with a female connector. *That's* what makes it
backwards, not merely the female connector by itself.
If it were a female connector, and wired as DCE, that would be unusual for
a computer, but it would still be conforming to the same conventions as
When you buy a random serial cable with male pins in a 25 pin connector, if
you know nothing about the insides of the cable or where it came from or
what the original packaging said etc, 99 44/100ths of the time that
combination expects to be plugged into a modem, or other DCE device. The
M100 isn't a modem, but if it's connector were wired DCE, that "modem"
cable would still work.
*today* such a plug would have an extra dimension of wrongness because it
would be ambiguous with a printer port, but at that time, D25F might not
yet have become a standard for parallel printer ports. It doesn't matter
that the printer port on the M100 itself isn't confusable with it's own
serial port, it's still a factor as long as a significant number of
printers and their cables out there can physically plug in to the wrong
port. At the time, that might not have been true like it absolutely is