>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

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