Arcane modem configuration (was Re: Modems on Ultrix)

[Greg Noel]

In article <1149 at ncr-sd.UUCP> I write:
>The computer will provide DTR to the modem even if it is ignoring DCD.

In article <12834 at amdcad.UUCP> phil at amdcad.UUCP (Phil Ngai) writes:
>In at least one version of 4.2 BSD, this is not true. When the system
>is configured to ignore modem controls, it fails to turn on DTR. .....

Humpf.  I was about to write a reply that pointed out that I probably had
a lot more experience in this than Phil did, and that I had never had a
port fail to turn on DTR, but I though I should check first.  It turns out
that he's right -- it's done on a per-driver basis, and I have never used
any hardware/driver combination that did it wrong.  Mea culpa.

I'm puzzled, though -- the RS-232 (et.seq.) protocol is \not/ that complicated,
but by the number of supposedly knowledgable people that get it just flat
wrong, there must be something subtle in it that causes confusion.
-- 
-- Greg Noel, NCR Rancho Bernardo    Greg at ncr-sd.UUCP or Greg at nosc.ARPA