From: Johnny Billquist <bqt@update.uu.se>
To: Noel Chiappa <jnc@mercury.lcs.mit.edu>,
ron@ronnatalie.com, TUHS main list <tuhs@minnie.tuhs.org>
Subject: Re: [TUHS] core
Date: Mon, 18 Jun 2018 23:13:32 +0200 [thread overview]
Message-ID: <f6d2ac5f-0e1f-0216-22dc-2913ac71fea8@update.uu.se> (raw)
In-Reply-To: <20180618121738.98BD118C087@mercury.lcs.mit.edu>
On 2018-06-18 14:17, Noel Chiappa wrote:
> > The "separate" bus for the semiconductor memory is just a second Unibus
>
> Err, no. :-) There is a second UNIBUS, but... its source is a second port on
> the FASTBUS memory, the other port goes straight to the CPU. The other UNIBUS
> comes out of the CPU. It _is_ possible to join the two UNIBI together, but
> on machines which don't do that, the _only_ path from the CPU to the FASTBUS
> memory is via the FASTBUS.
Ah. You and Ron are right. I am confused.
So there were some previous PDP-11 models who did not have their memory
on the Unibus. The 11/45,50,55 accessed memory from the CPU not through
the Unibus, but through the fastbus, which was a pure memory bus, as far
as I understand. You (obviously) could also have memory on the Unibus,
but that would be slower then.
Ah, and there is a jumper to tell which addresses are served by the
fastbus, and the rest then go to the Unibus. Thanks, I had missed these
details before. (To be honest, I have never actually worked on any of
those machines.)
Johnny
--
Johnny Billquist || "I'm on a bus
|| on a psychedelic trip
email: bqt@softjar.se || Reading murder books
pdp is alive! || tryin' to stay hip" - B. Idol
next parent reply other threads:[~2018-06-18 21:14 UTC|newest]
Thread overview: 73+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20180618121738.98BD118C087@mercury.lcs.mit.edu>
2018-06-18 21:13 ` Johnny Billquist [this message]
2018-06-21 22:44 Nelson H. F. Beebe
2018-06-21 23:07 ` Grant Taylor via TUHS
2018-06-21 23:38 ` Toby Thain
-- strict thread matches above, loose matches on Subject: below --
2018-06-21 17:40 Noel Chiappa
2018-06-21 17:07 Nelson H. F. Beebe
2018-06-21 13:46 Doug McIlroy
2018-06-21 16:13 ` Tim Bradshaw
2018-06-20 20:11 Doug McIlroy
2018-06-20 23:53 ` Tim Bradshaw
2018-06-19 12:23 Noel Chiappa
2018-06-19 12:58 ` Clem Cole
2018-06-19 13:53 ` John P. Linderman
2018-06-21 14:09 ` Paul Winalski
2018-06-19 11:50 Doug McIlroy
2018-06-18 17:56 Noel Chiappa
2018-06-18 18:51 ` Clem Cole
2018-06-18 14:51 Noel Chiappa
2018-06-18 14:58 ` Warner Losh
[not found] <mailman.1.1529287201.13697.tuhs@minnie.tuhs.org>
2018-06-18 5:58 ` Johnny Billquist
2018-06-18 12:39 ` Ronald Natalie
2018-06-17 21:18 Noel Chiappa
2018-06-17 17:58 Noel Chiappa
2018-06-18 9:16 ` Tim Bradshaw
2018-06-18 15:33 ` Tim Bradshaw
2018-06-17 14:36 Noel Chiappa
2018-06-17 15:58 ` Derek Fawcus
2018-06-16 22:57 Noel Chiappa
[not found] <mailman.1.1529175600.3826.tuhs@minnie.tuhs.org>
2018-06-16 22:14 ` Johnny Billquist
2018-06-16 22:38 ` Arthur Krewat
2018-06-17 0:15 ` Clem cole
2018-06-17 1:50 ` Johnny Billquist
2018-06-17 10:33 ` Ronald Natalie
2018-06-20 16:55 ` Paul Winalski
2018-06-20 21:35 ` Johnny Billquist
2018-06-20 22:24 ` Paul Winalski
2018-06-16 13:49 Noel Chiappa
2018-06-16 14:10 ` Clem Cole
2018-06-16 14:34 ` Lawrence Stewart
2018-06-16 15:28 ` Larry McVoy
2018-06-16 14:10 ` Steve Nickolas
2018-06-16 14:13 ` William Pechter
2018-06-16 13:37 Noel Chiappa
2018-06-16 18:59 ` Clem Cole
2018-06-17 12:15 ` Derek Fawcus
2018-06-17 17:33 ` Theodore Y. Ts'o
2018-06-17 19:50 ` Jon Forrest
2018-06-18 14:56 ` Clem Cole
2018-06-18 12:36 ` Tony Finch
2018-06-16 12:58 Doug McIlroy
2018-06-20 11:10 ` Dave Horsfall
2018-06-16 12:51 Noel Chiappa
2018-06-16 13:11 ` Clem cole
2018-06-15 15:25 Noel Chiappa
2018-06-15 23:05 ` Dave Horsfall
2018-06-15 23:22 ` Lyndon Nerenberg
2018-06-16 6:36 ` Dave Horsfall
2018-06-16 19:07 ` Clem Cole
2018-06-18 9:25 ` Tim Bradshaw
2018-06-19 20:45 ` Peter Jeremy
2018-06-19 22:55 ` David Arnold
2018-06-20 5:04 ` Peter Jeremy
2018-06-20 5:41 ` Warner Losh
2018-06-15 11:19 A. P. Garcia
2018-06-15 13:50 ` Steffen Nurpmeso
2018-06-15 14:21 ` Clem Cole
2018-06-15 15:11 ` John P. Linderman
2018-06-15 15:21 ` Larry McVoy
2018-06-16 1:08 ` Greg 'groggy' Lehey
2018-06-16 2:00 ` Nemo Nusquam
2018-06-16 2:17 ` John P. Linderman
2018-06-16 3:06 ` Clem cole
2018-06-20 10:06 ` Dave Horsfall
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