Parity on 4.x BSD UNIX ports

[Chris Torek]

In article <49535 at sun.uucp> guy at gorodish.Sun.COM (Guy Harris) writes:
>... turn[ing] on PASS8 in 4.3BSD ... puts the
>serial port hardware into "8 bits, no parity" mode.

Good point.  This will probably solve the original problem.

>>... Berkeley CSRG are working on a POSIX-like tty interface [me]

>I presume it's POSIX-compatible, not just "POSIX-like". [guy]

I said `POSIX-like' because, strictly speaking, POSIX does not exist
yet.  There is no absolute guarantee that the ultimate POSIX standard
will look anything at all like what we have now---not that I expect
anything drastic to happen.  Some minor tweak might make the interface
somehow incompatible, however; hence the weasel wording.

>> Sun may provide something useful soon, what with their AT&T deal.

>Actually, we'll provide it with SunOS 4.0. ...
>Basically, output is never stripped to 7 bits by the software; the only such
>stripping is done by the hardware if you set the character width to 7 bits.

There is some confusion here when you get to simplistic hardware that
does not do parity at all.  In that case I would assume the software
will emulate the nonexistent hardware stripping.  (Actually, if you set
the `device' to 7 bits, no parity, the driver is obliged to fake up a
parity bit [1 or 0, I forget] to emulate a stop bit, given the lack of
anything better, on such hardware.  Fortunately, we have no such
hardware around here, and I doubt Sun sells any either.  It would be
nice if asynch protocols were not so messy.)
-- 
In-Real-Life: Chris Torek, Univ of MD Comp Sci Dept (+1 301 454 7163)
Domain:	chris at mimsy.umd.edu	Path:	uunet!mimsy!chris