Type-ahead in unix

[Chris Torek]

In article <17309:Apr1614:19:5491 at kramden.acf.nyu.edu>
brnstnd at kramden.acf.nyu.edu (Dan Bernstein) writes:
>... The part I'm most impressed by is the way that characters are
>preserved when you switch from cbreak to cooked mode [in Ultrix 4.1]:
>I simply can't tell when the switch happened, because any typeahead
>is echoed properly and stuck back into the cooked cbuf so that line
>editing works.

(This is the right thing to do; it is also impossible in the `streams'
stuff in current SunOS releases, because the ldterm module may not pull
data back down from the streams head.  There are only two fixes: allow
data to be retracted, or do not send data upstream until it is requested.)

>It's years ahead of the latest releases from Convex and Sun,

Sun, at least, for the reason given above; but:

>not to mention 4.3-Reno.

huh?  4.3BSD (all releases thereof) have always done this.  What do
you think the PENDIN and catq() under TIOCSETA{,W} are doing in tty.c?
-- 
In-Real-Life: Chris Torek, Lawrence Berkeley Lab CSE/EE (+1 415 486 5427)
Berkeley, CA		Domain:	torek at ee.lbl.gov