Re: RS-232 port genders

[datajerk <datajerk@gmail.com>]

On Jun 21, 10:37 am, schmidtd <schmi...@my-deja.com> wrote:
> On Jun 21, 12:33 pm, datajerk <dataj...@gmail.com> wrote:
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> > On Jun 21, 9:47 am, datajerk <dataj...@gmail.com> wrote:
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> > > I worked with a lot of RS-232 devices in the mid '80s to the early
> > > '90s.  Dumb terminals, modems, printers, Alpha Micros, the Apple II,
> > > short-hall modems, data collection devices, many different RS-232
> > > multiplexers to add terminals to various UNIX systems, etc...
> > > Excluding a few oddballs (e.g. Macs) they all used female DB25
> > > connectors except, IIRC, IBM PCs (and later the multiplexers started
> > > to use RJ45s).  The PCs used a female DB25 for the parallel port and a
> > > male DB25 for the serial port.  I always thought this was a poor
> > > decision since repairing broken pins on a cable was cheaper than a
> > > device.
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> > > As I dug through my vintage serial devices I found a 1985 HP-IL to
> > > RS232C device used to provide a serial port to HP-IL devices such as
> > > the HP41 calculator.  It also has a male serial port.  That has left
> > > me with the thought that something greater was redefining the
> > > convention or was it simply the PC that started the trend to use male
> > > RS-232 ports primarily on computers?
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> > > In any case, what got me thinking about this was the installation of a
> > > newly acquired SSC card for my IIe.  Given my history I was neither
> > > shocked or surprised, but it got me thinking.
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> > > I plan to build my own cable for the SSC with a male DB25 to conform
> > > with convention and to distinguish it from the female DB25 port I plan
> > > to install for my printer card.  Perhaps that was IBM's thinking as
> > > well.
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> > I failed to mention that the SSC came with a female DB25.
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> From Wikipedia on RS-232, FWIW:
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> "RS-232 devices may be classified as Data Terminal Equipment (DTE) or
> Data Communication Equipment (DCE); this defines at each device which
> wires will be sending and receiving each signal. The standard
> recommended but did not make mandatory the D-subminiature 25 pin
> connector. In general and according to the standard, terminals and
> computers have male connectors with DTE pin functions, and modems have
> female connectors with DCE pin functions. Other devices may have any
> combination of connector gender and pin definitions. Many terminals
> were manufactured with female terminals but were sold with a cable
> with male connectors at each end; the terminal with its cable
> satisfied the recommendations in the standard."

Yeah I read that too, but could not find a date of the "standard".