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From: jr@LF-SERVER-2.BBN.COM (John Robinson)
Newsgroups: comp.emacs
Subject: Re: How we could have made flow control livable
Message-ID: <8706251419.AA20423@ucbvax.Berkeley.EDU>
Date: Thu, 25-Jun-87 10:52:11 EDT
Article-I.D.: ucbvax.8706251419.AA20423
Posted: Thu Jun 25 10:52:11 1987
Date-Received: Sat, 27-Jun-87 02:04:56 EDT
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>> The unix TTY driver could have been written
>> in a way to make this all much easier, if it had allowed ^S and ^Q
>> to be escaped by preceeding them with backslash.

Or map ^S to \023 and ^Q to \021 (and \ to \\ maybe).  That avoids
having to synchronize the two directions (impossible if anyting
"intelligent" out there wants to interpose flow control anyway).  Or
have a "controlify-following" or maybe "flip-control-bit-on-following"
escape/prefix.  The latter was a clever suggestion in a protocol
proposal I saw from Hayes for doing reliable transmission over phone
lines.  It was packet-oriented (too hard for Unix tty and "dumb"
terminals probably), but the flow-control didn't reserve any
characters (i.e. it was transparent to any 8-bit character coding you
wanted to send).

But this is the emacs list ... which brings me to: I remember from my
TENEX/ITS/Tops20 days that there used to be a one-character
"control-prefix" character in original EMACS that read the next
character and did the obvious thing.  Maybe this would help the
keyboard-remap question that has been popping up of late.  Left as an
exercise for the reader.

In ol' EMACS, it was control-Z (actually, I think it started out as
^C, but DEC operating systems really wanted that to be
interrupt-process so RMS relented).  ^Z-s was the same as ^S.  ^Z is
pretty easy to type.  But then job-control Unix wants ^Z for pausing a
process, which is its usual default binding, but that could be ^Z-^Z
or some such cleverness.

/jr