Date:        Tue, 02 Nov 1999 09:32:53 +0100
    From:        Harald Barth <haba@pdc.kth.se>
    Message-ID:  <19991102093253Z.haba@pdc.kth.se>

  | There are terminals around with female DTE, but most terminals are DTE
  | as the T in DTE stands for Terminal.

It does, but the "terminal" in DTE is the kind of "terminal" that means
"the end", and has not much to do with the things computer people call
"terminals" (vt320s and such).  It is entirely possible (I have no idea,
and had never thought it before) that we call vt320s "terminals" because
they are/were a very common form of DTE.

The T in DTE is meant to indicate "the end of the wire" - that's where
the data originated, or is going (as far as the serial communications are
concerned, where some application decides to forward it is another issue).

  | The Sun is (as a lot of computers are) DTE, too.

All computers should be.   They're the other "end of the wire".

  | But with a female connector.

Yes, the standards actually say what kind of connector should be on what
kind of equipment, but this is the one aspect most commonly violated.
I think DEC have it right.

  | Most modems are DCE and have a female connector. The C stands for
  | Control and of course you control your computer with a modem ;-)

Actually, the 'C' stands for communications - that's equipment used by
other equipment to enable the communications to work, so there is some
kind of terminal equipment at each end of the link communicating with
each other, and possibly some amount of communications equipment in
between helping make all of that work.

I have never seen a modem that pretends to be a DTE (that would be wild)
though I have certainly seen brain dead terminal equipment (end points)
which insists on being DCE (supposedly so a straight through RS232 cable
can be used to connect a "terminal" though I once heard someone claim that
computers were "communications equipment" - and actually with a straight
face).

  | To compilicate things a bit more, some Suns (the ones with A/B text
  | under the RS232 connector) have a second terminal line on the normally
  | unused pins in the same connector.

Normally unused, yes, but the secondary channels are defined in the
standard.  Using them the way sun uses them is entirely reasonable,
given the pressure on connector space on the boxes that do that.  They're
not as convenient as two connectors - but they're a hell of a lot nicer
than being stuck with DB9 (or worse, mini DIN 8) connectors.

kre