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From: jdb@mordor.s1.gov (John Bruner)
Newsgroups: comp.arch
Subject: Re: paging in the terminal driver
Message-ID: <17321@mordor.s1.gov>
Date: Fri, 30-Oct-87 17:08:08 EST
Article-I.D.: mordor.17321
Posted: Fri Oct 30 17:08:08 1987
Date-Received: Wed, 4-Nov-87 23:53:09 EST
References: <573@elxsi.UUCP> <682@its63b.ed.ac.uk> <796@quacky.UUCP> <1444@osiris.UUCP> <858@gumby.UUCP>
Reply-To: jdb@mordor.UUCP (John Bruner)
Organization: S-1 Project, LLNL
Lines: 21
Keywords: output pagination

When the subject of terminal output paging came up in
"net.unix-wizards" a while back, Dennis Ritchie commented that
PDP-7 UNIX did provide autopaging (eliminating an appeal to an
historical precedent against automatic output pagination).

As far as simplicity goes, UNIX terminal drivers are one of the
messiest, most kludged-up pieces of code that I've seen.  The BSD
driver is particularly nauseating; the interface to it is far from
clean and simple (e.g. how many ioctl's does it take to initialize a
terminal's state?).  One can still see the V6 driver hiding under
V7 extensions plus nifty CRT-oriented editing extensions plus
job control extensions plus ....  In the light of all of this,
I have difficulty accepting the argument that autopaging does not
belong in the kernel for reasons of simplicity and elegance.

The right solution is to toss out all of this garbage and use
streams, so that users who want autopaging can push a paging filter
onto their terminal output stream.  I wish I had a V8 (or V9)....
-- 
  John Bruner (S-1 Project, Lawrence Livermore National Laboratory)
  jdb@mordor.s1.gov	...!seismo!mordor!jdb		(415) 423-4848