On 02/02/2025 07:29, Tony Duell via cctalk wrote:
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'!" :-)
Once saw an IBM Quietwriter damaged by that very action. It was not
happy with 12v on its Centronics port..
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
Dave
G4UGM
