Path: utzoo!mnetor!uunet!husc6!cmcl2!rutgers!pyrnj!romain
From: romain@pyrnj.uucp (Romain Kang)
Newsgroups: comp.sys.pyramid
Subject: Re: Using DEC vt[2,3]xx terminals with UNIX
Message-ID: <734@pyrnj.uucp>
Date: 24 Dec 87 16:51:36 GMT
References: <4212@trwrb.UUCP>
Reply-To: romain@pyrnj.UUCP (Romain Kang)
Organization: Pyramid Technology Corp, Woodbridge, NJ
Lines: 69
Keywords: 8-bit tty data

[I followed up to comp.sys.pyramid only, since there is so much
Pyramid-specific stuff here.]

In article <4212@trwrb.UUCP> jumper@trwrb.UUCP (Gregory S. Jumper) writes:
| I would like the terminal driver to pass all eight bits unscathed to and from
| my terminal without my having to put the driver into "raw" mode (and lose line
| editing).

The "recommended" way to do this under OSx (3.2 and later) involves
twiddling a flag in /usr/sys/conf/param.c.  I quote from my param.c:

/*
 * Support for 8-bit tty I/O.
 * This allows full 8-bit tty input and output in canonical mode using:
 *
 *	att stty cs8 -parenb -istrip
 * or
 *	ucb stty -even -odd 
 */
int eightbitttyio = 0;

I won't have a chance to try this myself before the New Year, but I
suspect no one else may see your message before then, either...

(For the record, those of you who *must* adb your OSx kernels with
/dev/kmem need to change adb's address map:
	0xff000000>1
	?m <1 <1+<t
	?*m <1+<b <1+<b+<d
	/m 0 0xffffffff 0x1000
There is no VM simulation; if you want to look at /dev/mem or core
images, you'll need to configure your system with the kernel debugger,
or use the crash analyzer.  If you don't know what this "adb" stuff is,
you don't want to know.  And naturally, you can't call RTOC if you zap
your system with adb... :-)

| Now, if the above problem has a solution, what about the fact that the
| terminal driver is in its "brain-damaged" state at login time, before one has
| the chance to issue an "stty" or equivalent command?
| [...]  (For example, the description of
| "gettytab" indicates that it is possible to have any parity accepted on input
| and have odd parity generated on output, but it says nothing about having no
| parity generated on output.)  

getty normally operates in raw mode.  Therefore it should be necessary
to simply turn off even parity and odd parity:
	:ep@:op@:

| [...]  In this day of "eight *data* bits, no parity"
| data communications and extended character sets, why is UNIX apparently so
| backwards in its terminal driver?

You actually speak of Version 7-derived line disciplines.  I believe
UNIX variants supported by large vendors will all have to support 8-bit
tty data because of the needs of internationalization.  For the time
being, though, there's a lot of V7-based stuff out there that people
aren't too eager to hack.  All the "local mode" stuff in the BSD tty
interface is esthetically displeasing to me, even though I do use it.

The System V line discipline is better-designed, since it distinguishes
between various line attributes more cleanly.  It seems a more elegant
model for UNIX tty interfaces of the future, though there are a few
gotcha's that are not documented or non-obvious.  And again, there's a
question of inertia.  See the System V man pages for termio.7.
--
Romain Kang		{allegra,cmcl2,mirror,pyramid,rutgers}!pyrnj!romain
Pyramid Technology Corp. / 10 Woodbridge Center. Dr / Woodbridge, NJ  07095

"Eggheads unite! You have nothing to lose but your yolks!" -Adlai Stevenson