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From: gww@aphasia.UUCP (George Williams)
Newsgroups: net.unix-wizards
Subject: Re: Re: Pagination in TTY driver
Message-ID: <311@aphasia.UUCP>
Date: Wed, 11-Sep-85 14:45:27 EDT
Article-I.D.: aphasia.311
Posted: Wed Sep 11 14:45:27 1985
Date-Received: Sun, 15-Sep-85 23:46:58 EDT
References: <2067@ucf-cs.UUCP> <363@cuae2.UUCP> <2423@sun.uucp> <5937@utzoo.UUCP>
Organization: Green Hills Software, Pasadena, CA
Lines: 33

> >    At caltech we have a network that lives between most computers and
> >    most terminals, now unfortunately the network uses ^S/^Q (of course)
> >    and any ^S, ^Q you type on your terminal will go to the network
> >    not to the computer.  So putting pagination in the tty driver
> >    really confuses novice users, the documentation says that pressing
> >    ^Q gets things started again, but it doesn't...
>
> As has already been pointed out, using ^Q to restart paging is a terrible
> mistake because it is increasingly necessary to reserve ^S^Q exclusively
> for low-level flow control.  Don't confuse this implementation mistake with
> a general problem with the concept.

Actually I rather like pagenators, I was just objecting to the use of ^Q
to start them up again.  I also object to people's suggestion that a space
be used and then vanish; I have a strong believe that non-control characters
should hang around (control characters are designed to control things,
other characters are designed as text).  Not even the bsd terminal driver
uses all the control chars, there are still plenty left.

Of course the best thing to do is to have the magic character that restarts
output to be set by an ioctl, but its default should be neither ^Q nor space.

I also don't understand why some people have their paginators turned off by
input; I like typeahead but I don't always want it to turn off my output
control.  It seems to me that having yet another magic character to turn off
pagenation would be preferable.

Since I seem to be on the subject of magic characters, I have always liked
dec's ^T that generates a line with some status info on it. I have seen
this implemented on one unix system (cithep) rather well; where ^T (setable
with an ioctl of course) generated a signal that was normally ignored, but
if a program wanted to, it could be used.  This character did not flush
either the input or output buffer.


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