From: bqt@update.uu.se (Johnny Billquist)
Subject: [TUHS] /dev/drum
Date: Thu, 26 Apr 2018 01:08:14 +0200 [thread overview]
Message-ID: <7193c242-fa54-8f95-71a1-e22e7f70975a@update.uu.se> (raw)
In-Reply-To: <mailman.143.1524696952.3788.tuhs@minnie.tuhs.org>
On 2018-04-26 00:55, jnc at mercury.lcs.mit.edu (Noel Chiappa) wrote:
> > From: Johnny Billquist
>
> > PDP-11 have 8K pages.
>
> Segments.:-) (This is an old argument between Johnny and me, I'm not trying
> to re-open it, just yanking his chain...:-)
:-)
And if you hadn't had the ability for them to be less than 8K, you
wouldn't even try that argument. But just because the hardware gives you
some extra capabilities, you suddenly want to associate them with a
technology that really gives you much less capabilities.
Either way, the next page always start at the next 8K boundary.
> > On a PDP-11, all your virtual memory was always there when the process
> > was on the CPU
>
> In theory, at least (I don't know of an OS that made use of this), didn't the
> memory management hardware allow the possibility to do demand-paging? I note
> that Access Control Field value 0 is "non-resident".
Oh yes. You definitely could do demand paging based on the hardware
capabilities.
> Unix kinda-sorta used this stuff, to automatically extend the stack when the
> user ran off the end of it (causing a trap).
Ah. Good point. The same is also true for brk, even though that is an
explicit request to grow your memory space at the other side.
DEC OSes had the brk part as well, but stack was not automatically
extended if needed. DEC liked to have the stack at the low end of
address space, and have hardware that trapped if the stack grew below
400 (octal).
> > you normally did not have demand paging, since that was not really
> > gaining you much on a PDP-11
>
> Especially on the later machines, with more than 256KB of hardware main
> memory. Maybe it might have been useful on the earlier ones (e.g. the -11/45).
Yeah, it would actually probably have been more useful on an 11/45.
Johnny
--
Johnny Billquist || "I'm on a bus
|| on a psychedelic trip
email: bqt at softjar.se || Reading murder books
pdp is alive! || tryin' to stay hip" - B. Idol
next parent reply other threads:[~2018-04-25 23:08 UTC|newest]
Thread overview: 105+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <mailman.143.1524696952.3788.tuhs@minnie.tuhs.org>
2018-04-25 23:08 ` Johnny Billquist [this message]
[not found] <mailman.1.1525744802.16322.tuhs@minnie.tuhs.org>
2018-05-08 22:39 ` Johnny Billquist
2018-05-07 15:36 Noel Chiappa
-- strict thread matches above, loose matches on Subject: below --
2018-05-06 13:07 Noel Chiappa
2018-05-06 15:57 ` Johnny Billquist
2018-05-05 13:06 Noel Chiappa
2018-05-05 20:53 ` Johnny Billquist
2018-05-03 11:39 Noel Chiappa
2018-05-03 21:22 ` Johnny Billquist
2018-04-30 15:05 Noel Chiappa
2018-04-30 16:43 ` Paul Winalski
2018-04-30 21:41 ` Johnny Billquist
2018-05-03 2:54 ` Charles Anthony
2018-04-28 20:40 Noel Chiappa
2018-04-29 15:37 ` Johnny Billquist
2018-04-29 16:34 ` Steve Nickolas
2018-04-29 16:48 ` Warner Losh
2018-04-28 0:19 Noel Chiappa
2018-04-28 10:41 ` Johnny Billquist
2018-04-28 12:19 ` Rico Pajarola
2018-04-27 23:01 Noel Chiappa
2018-04-27 23:10 ` Johnny Billquist
2018-04-27 23:39 ` Warner Losh
[not found] <mailman.1.1524708001.6296.tuhs@minnie.tuhs.org>
2018-04-27 22:41 ` Johnny Billquist
2018-04-26 1:53 Noel Chiappa
2018-04-25 22:55 Noel Chiappa
[not found] <mailman.139.1524690859.3788.tuhs@minnie.tuhs.org>
2018-04-25 22:54 ` Johnny Billquist
2018-04-25 22:46 Noel Chiappa
[not found] <mailman.137.1524667148.3788.tuhs@minnie.tuhs.org>
2018-04-25 21:43 ` Johnny Billquist
2018-04-25 22:24 ` Johnny Billquist
2018-04-26 5:51 ` Tom Ivar Helbekkmo
2018-04-25 22:37 ` Johnny Billquist
2018-04-24 7:10 Rudi Blom
[not found] <mailman.125.1524526228.3788.tuhs@minnie.tuhs.org>
2018-04-23 23:44 ` Johnny Billquist
2018-04-23 23:57 ` Steve Nickolas
2018-04-24 0:24 ` Ronald Natalie
2018-04-24 0:25 ` Warren Toomey
2018-04-24 0:31 ` Dave Horsfall
2018-04-24 1:02 ` Lyndon Nerenberg
2018-04-24 4:32 ` Grant Taylor
2018-04-24 4:49 ` Bakul Shah
2018-04-24 4:59 ` Warner Losh
2018-04-24 6:22 ` Bakul Shah
2018-04-24 14:57 ` Warner Losh
2018-04-24 6:46 ` Lars Brinkhoff
2018-04-23 22:01 Noel Chiappa
2018-04-23 22:09 ` Warner Losh
2018-04-23 18:41 Noel Chiappa
2018-04-23 19:09 ` Clem Cole
2018-04-23 23:01 ` Dave Horsfall
2018-04-23 23:49 ` Dave Horsfall
2018-04-24 0:26 ` Ronald Natalie
2018-04-22 18:06 Norman Wilson
2018-04-20 16:45 Noel Chiappa
2018-04-20 16:53 ` Charles Anthony
2018-04-20 17:16 ` William Pechter
2018-04-20 23:35 ` Dave Horsfall
2018-04-22 11:48 ` Steve Simon
2018-04-20 15:02 Tim Bradshaw
2018-04-20 15:58 ` Clem Cole
2018-04-20 16:00 ` David Collantes
2018-04-20 16:12 ` Dan Cross
2018-04-20 16:21 ` Clem Cole
2018-04-20 16:33 ` Warner Losh
2018-04-20 19:17 ` Ron Natalie
2018-04-20 20:23 ` Clem Cole
2018-04-20 22:10 ` Dave Horsfall
2018-04-22 17:01 ` Lars Brinkhoff
2018-04-22 17:37 ` Clem Cole
2018-04-22 19:14 ` Bakul Shah
2018-04-22 20:58 ` Mutiny
2018-04-22 22:37 ` Clem cole
2018-04-22 21:51 ` Dave Horsfall
2018-04-25 1:27 ` Dan Stromberg
2018-04-25 12:18 ` Ronald Natalie
2018-04-25 13:39 ` Tim Bradshaw
2018-04-25 14:02 ` arnold
2018-04-25 14:59 ` tfb
2018-04-25 14:33 ` Ian Zimmerman
2018-04-25 14:46 ` Larry McVoy
2018-04-25 15:03 ` ron minnich
2018-04-25 20:29 ` Paul Winalski
2018-04-25 20:45 ` Larry McVoy
2018-04-25 21:14 ` Lawrence Stewart
2018-04-25 21:30 ` ron minnich
2018-04-25 23:01 ` Bakul Shah
2018-04-23 16:42 ` Tim Bradshaw
2018-04-23 17:30 ` Ron Natalie
2018-04-23 17:51 ` Clem Cole
2018-04-23 18:30 ` Ron Natalie
2018-04-25 14:02 ` Tom Ivar Helbekkmo
2018-04-25 14:38 ` Clem Cole
2018-04-23 20:47 ` Grant Taylor
2018-04-23 21:06 ` Clem Cole
2018-04-23 21:14 ` Dan Mick
2018-04-23 21:27 ` Clem Cole
2018-04-23 22:07 ` Tim Bradshaw
2018-04-23 22:15 ` Warner Losh
2018-04-23 23:30 ` Grant Taylor
2018-04-24 9:37 ` Michael Kjörling
2018-04-24 9:57 ` Dave Horsfall
2018-04-24 13:01 ` Nemo
2018-04-24 13:03 ` Arthur Krewat
2018-04-23 23:45 ` Arthur Krewat
2018-04-24 8:05 ` tfb
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