Subject: Re: Problem with the 3/7 sources.
To: Chris G. Demetriou <>
From: Perry E. Metzger <>
List: current-users
Date: 03/13/1994 23:36:16
"Chris G. Demetriou" says:
> > And good ideas should not be subject to O/S religious wars.
> true, though i've still not been convinced that the 'cua' thing
> is a 'good idea.'

The /dev/tty?? /dev/cua??  idea is a very nice and simple way your
programs can use a line for both dial in and dial out without having
to know much about the serial drivers. A single line can have a getty
waiting on it to open the dial in line while uucp happily opens up the
outgoing device and transfers a file -- systems that DON'T provide the
cua hack can't do this conveniently. Many small systems have just the
one modem on them; this accomodates them very nicely without having to
have kludgy scripts to kill getty or what have you. The hack is also
un the BSD spirit. It follows in the tradition of having tape drivers
in which the minor device number let you select options (like density
and rewind on close) so that your tape handling program (like tar)
doesn't need to know too much about the tape drivers. Overall, its a
Good Thing.

And now for a bit of a ramble.

Serial lines are gross to begin with; the tty driver contains some of
the ugliest and most complicated interfaces in Unix. This is not an
accident. The RS232 interface is old and way too complicated, with so
many optional features that people have to spend considerable time
debugging serial hardware and software even though its conceptually
far far simpler than stuff like SCSI.  Only two weeks ago I spent an
hour debugging a SLIP problem that turned out to be XON/XOFF flow
control getting invoked where it should have been using hardware flow
control. I know what I'm doing and this sort of stuff still
occassionally rises from the swamp to bite me in the ass. The tty
driver is ugly looking in its interface entirely because RS232 is so

Its time someone defined a newer and better standard. There is
something wrong when your serial connectors are bigger than your disk
connectors and MUCH bigger than your network connectors, and are far
more complicated to use. A self configuring very high speed serial
interface with RJ11 size connectors would be a Good Thing.