From: John Cowan <cowan@ccil.org>
To: Warner Losh <imp@bsdimp.com>
Cc: The Eunuchs Hysterical Society <tuhs@tuhs.org>
Subject: Re: [TUHS] One's complement (was: reviving a bit of WWB)
Date: Thu, 24 Sep 2020 21:39:46 -0400 [thread overview]
Message-ID: <CAD2gp_TqMB84uP75jbgeTsc1mgwZb_mcCoMbUKfogF909xas6g@mail.gmail.com> (raw)
In-Reply-To: <CANCZdfpFVWBbexxM2LmO13DGf2BsHKqCTiJig0tZgXqPitHjWQ@mail.gmail.com>
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On Thu, Sep 24, 2020 at 8:22 PM Warner Losh <imp@bsdimp.com> wrote:
Don't know about the others, but I'm pretty sure PDP-10 wasn't 1's
>> compliment / was 2's compliment..
>
>
Correct. The PDP-1 (18 bits) was DEC's 1's complement machine. Its direct
successors the 4/7/9/15 had both 1's and 2's complement arithmetic. The
12-bit 5/8/12 machines had only 2's complement, but retained the PDP-4
mnemonic TAD (Two's-complement Add). By the time the 36-bit 6/10/20 line
was designed, it was clear that 1's complement was history, and the
mnemonic was changed to ADD.
(The PDP-3 was a PDP-1 with a 36-bit data path, and only one ever went into
production; the PDP-2 was to be a 24-bit machine, perhaps a compromise
between 6-bit and 8-bit byte systems, but was never even designed.)
John Cowan http://vrici.lojban.org/~cowan cowan@ccil.org
I marvel at the creature: so secret and so sly as he is, to come sporting
in the pool before our very window. Does he think that Men sleep without
watch all night? --Faramir
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next prev parent reply other threads:[~2020-09-25 1:40 UTC|newest]
Thread overview: 44+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-09-19 1:51 [TUHS] reviving a bit of WWB Doug McIlroy
2020-09-20 18:42 ` arnold
2020-09-20 19:28 ` Will Senn
2020-09-20 20:12 ` Steve Nickolas
2020-09-20 20:26 ` Doug McIlroy
2020-09-20 20:57 ` Doug McIlroy
2020-09-20 22:13 ` Clem Cole
2020-09-21 20:43 ` Steffen Nurpmeso
2020-09-20 20:58 ` Steve Nickolas
2020-09-20 21:33 ` Brantley Coile
2020-10-07 5:43 ` scj
2020-09-20 21:35 ` John Cowan
2021-02-02 23:08 ` Greg A. Woods
2021-02-02 23:47 ` Larry McVoy
2021-02-03 0:11 ` Dave Horsfall
2021-02-03 0:19 ` Larry McVoy
2021-02-03 2:04 ` Richard Salz
2021-02-03 3:32 ` Dave Horsfall
2021-02-03 4:32 ` M Douglas McIlroy
2021-02-03 11:27 ` Peter Jeremy via TUHS
2021-02-03 20:09 ` Dave Horsfall
2021-02-03 20:13 ` Niklas Karlsson
2021-02-03 23:46 ` Tom Lyon
2021-02-03 22:19 ` Dave Horsfall
2021-02-03 22:55 ` M Douglas McIlroy
2020-09-20 22:15 ` Clem Cole
2020-09-20 22:47 ` John Cowan
2020-09-21 20:48 ` Steffen Nurpmeso
2020-09-21 20:46 ` Steffen Nurpmeso
2020-09-24 2:25 ` Dave Horsfall
2020-09-24 2:33 ` Clem Cole
2020-09-25 0:18 ` [TUHS] One's complement (was: reviving a bit of WWB) Greg 'groggy' Lehey
2020-09-25 0:22 ` Warner Losh
2020-09-25 1:39 ` John Cowan [this message]
2020-09-27 5:54 ` [TUHS] reviving a bit of WWB Dave Horsfall
2020-09-24 17:19 ` Paul Winalski
2020-09-24 18:17 ` John Cowan
2020-10-07 5:47 ` scj
2020-10-07 9:20 ` arnold
2020-10-08 0:27 ` Dave Horsfall
2020-10-08 3:08 ` John Cowan
2020-09-25 15:21 [TUHS] One's complement (was: reviving a bit of WWB) Noel Chiappa
2020-09-25 15:30 ` Warner Losh
2020-09-25 16:10 ` Ronald Natalie
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