2 Feb
2025
2 Feb
'25
4:42 p.m.
Message: 31
Date: Sun, 2 Feb 2025 07:29:15 +0000
From: Tony Duell <ard.p850ug1(a)gmail.com>
Subject: [cctalk] Re: RS232 then and now
On Sat, Feb 1, 2025 at 10:54 PM Fred Cisin via cctalk
<cctalk(a)classiccmp.org> wrote:
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
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