From: jnc@mercury.lcs.mit.edu (Noel Chiappa)
Subject: [TUHS] pre-more pager?
Date: Wed, 8 Nov 2017 15:02:22 -0500 (EST) [thread overview]
Message-ID: <20171108200222.B6A6F18C0B9@mercury.lcs.mit.edu> (raw)
> From: Jon Forrest
> In the early days of Unix I was told that it wasn't practical to write a
> pager because such a thing would have to run in raw mode in order to
> process single letter commands, such as the space character for going on
> to the next page. Since raw mode introduced a significant amount of
> overhead on already overtaxed machines, it was considered an anti-social
> thing to do.
Something sounds odd here.
One could have written a pager which used 'Return' for each new page, and run
it in cooked mode and not used any less cycles (in fact, more, IIRC the
cooked/raw differences in handling in the TTY driver).
But that's all second-order effects anyway. If one were using a serial line
hooked up to a DZ (and those were common - DH's were _much_ more expensive, so
poor places like my lab at MIT used DZ's), then _every character printed_
caused an interrupt. So the overhead from printing each screen-ful of text was
orders of magnitude greater than the overhead of the user's input to get the
next screen.
> IIRC later versions of Unix added the ability to respond to a specific
> list of single characters without going into raw mode. Of course, that
> didn't help when full-screen editors like vi and the Rand editor came
> out.
Overhead was definitely an issue with EMACS on Multics, where waking up a
process on each character of input was significant. I think Bernie's Multics
EMACS document discusses this. I'm pretty sure they used the Telnet RCTE
option to try and minimize the overhead.
Noel
next reply other threads:[~2017-11-08 20:02 UTC|newest]
Thread overview: 42+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-11-08 20:02 Noel Chiappa [this message]
2017-11-08 20:11 ` Forrest, Jon
2017-11-10 5:26 ` Random832
2017-11-10 7:31 ` Otto Moerbeek
2017-11-08 20:18 ` Clem Cole
2017-11-08 20:28 ` Ron Natalie
2017-11-08 22:47 ` Dave Horsfall
-- strict thread matches above, loose matches on Subject: below --
2017-11-09 16:19 Norman Wilson
2017-11-09 16:48 ` Arthur Krewat
2017-11-09 17:19 ` Steve Nickolas
2017-11-09 18:15 ` Don Hopkins
2017-11-09 18:26 ` Arthur Krewat
2017-11-09 13:33 Doug McIlroy
2017-11-08 22:58 Doug McIlroy
2017-11-08 22:02 Paul Ruizendaal
2017-11-08 22:20 ` Will Senn
2017-11-08 20:28 Noel Chiappa
2017-11-08 19:23 Noel Chiappa
2017-11-08 18:54 Will Senn
2017-11-08 18:59 ` Clem Cole
2017-11-08 19:06 ` Arthur Krewat
2017-11-08 19:31 ` Jeremy C. Reed
2017-11-08 22:43 ` Dave Horsfall
2017-11-08 22:47 ` Arthur Krewat
2017-11-08 23:21 ` Dave Horsfall
2017-11-09 4:38 ` Will Senn
2017-11-09 13:18 ` Dan Cross
2017-11-09 14:29 ` Will Senn
2017-11-09 20:53 ` Dave Horsfall
2017-11-10 0:15 ` Arthur Krewat
2017-11-10 2:14 ` Ralph Corderoy
2017-11-08 19:12 ` Bakul Shah
2017-11-08 19:22 ` Random832
2017-11-08 21:18 ` Will Senn
2017-11-08 21:59 ` Ron Natalie
2017-11-08 22:00 ` Clem Cole
2017-11-08 22:18 ` Will Senn
2017-11-09 2:01 ` Steve Johnson
2017-11-09 2:16 ` Lyndon Nerenberg
2017-11-08 19:29 ` Forrest, Jon
2017-11-08 19:43 ` Ron Natalie
2017-11-08 21:03 ` Mark Green
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