Path: utzoo!attcan!utgpu!jarvis.csri.toronto.edu!mailrus!wuarchive!wugate!uunet!munnari.oz.au!cs.mu.oz.au!ok
From: ok@cs.mu.oz.au (Richard O'Keefe)
Newsgroups: comp.unix.questions
Subject: Re: How does man know?
Message-ID: <2323@munnari.oz.au>
Date: 7 Oct 89 10:18:12 GMT
References: <319@massey.ac.nz> <11170@smoke.BRL.MIL> <592@crdos1.crd.ge.COM> <1456@mdbs.UUCP>
Sender: news@cs.mu.oz.au
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In article <1456@mdbs.UUCP>, wsmith@mdbs.UUCP (Bill Smith) writes:

> What exactly is meant by "putting the paginator in the kernel or terminal"?
Precisely that.  If you want to skip all around a document, you can use a
screen editor, and there is no problem.  The problem is that you can send
a stream of bytes to a terminal (and the terminal can display them) faster
than a human being can read them, so the output rate needs to be controlled
by the individual human being doing the reading.  This is not specific to
any one program, it is a problem that applies to every single program.
(It even applies to programs that can generate only one line of output;
run such a program in a shell loop and you're watching information flash
off the top of the screen in no time.)  One method of controlling the
output rate is explicit XON/XOFF keystrokes from the user.  The snag is
that even when I type fast enough, the computer at the end doesn't
_listen_ soon enough.  VT100s had a "slow scroll" feature toggled by a
key on the keyboard where the text would slowly and smoothly scroll up
the screen, XON/XOFF being sent automatically by the terminal.  I hated
it, because I don't like reading moving text, but it works, and it's a
paging-type feature in the terminal.  Another flow control method is for
the terminal to send ^S as soon as it has a screenful and then wait for
the human being to type ^Q.  Or the terminal driver can do it if the
terminal can't.  Or the terminal emulator can do it if the driver can't.

> To me that brings up visions of an IBM mainframe and 3270 terminals where 
> one is *forced* to use the pager, even when you only want to scan the 
> output and do not need to examine every line in glorious detail.
It has been repeatedly stated that the feature as present in EUUG V7 UNIX
(the Heriot-Watt terminal driver) and SunOS (the SunView terminal emulator)
is very easy to disable.

> I don't want the cure to be worse than the disease.
The feature was demonstrably cheap: EUUG V7 ran on PDP-11s without
separate I/D, and didn't cause kernel bloat.  It could be disabled so
that you never knew about it.  How is that worse than the disease?