On Sat, Feb 1, 2025 at 10:54 PM Fred Cisin via cctalk
<cctalk@classiccmp.org> wrote:


>
> IBM used a DB25 socket for their printer port at the computer end,
> (male on the card for serial, female on the card for parallel "Centronics")
> THAT, of course caused some idiots to attempt to use the parallel port for
> serial and vice versa.  "I just need a 'gender changer'!" :-)

The worst screw-up there (IMHO) came from HP in the HP150 series. This
machine had 2 RS232 serial ports as standard on DB25 sockets, wired
for some inexplicable reason as DTEs. There was an add-on board that
included a parallel printer port. To avoid confusion, this was a DB25
plug. But the board had been laid out for a DB25 socket using the IBM
PC pinout. The result was that stb/ ended up on pin 13, D0 on pin 12,
and so on.

-tony

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