>Message: 31 >Date: Sun, 2 Feb 2025 07:29:15 +0000 >From: Tony Duell <ard.p850...@gmail.com> >Subject: [cctalk] Re: RS232 then and now > >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 >
My vote for the worst connector screw-up is the AT&T (Olivetti) 6300. Its monochrome monitor used a DB25 to supply both the signals and 12 volts to power the monitor. Bob
