From: Rich Morin <rdm@cfcl.com>
To: TUHS main list <tuhs@minnie.tuhs.org>
Subject: Re: [TUHS] 2^n-bit operands (Was reviving a bit of WWB)
Date: Wed, 3 Feb 2021 13:10:02 -0800 [thread overview]
Message-ID: <3268852D-6845-4F4B-8EFC-3A1D78A11059@cfcl.com> (raw)
In-Reply-To: <CAD2gp_Rjn2z1SMitQ0VX-NASHdEJ3GcmeZaaTq_iCHwF4xiGVA@mail.gmail.com>
> On Feb 3, 2021, at 12:07, John Cowan <cowan@ccil.org> wrote:
>
> On the 36-bit PDP-10, things were better: the sign bit was mostly ignored and five 7-bit ASCII characters were packed into each word, again with NUL padding. (Line editors turned on the sign bit to indicate that this word held an explicit ASCII line number.)
The PDP-7, 9, and 15 used 18-bit words, but used the same "5/7 IOPS ASCII" packing strategy. That is, five 7-bit ASCII characters were packed into a word pair. Unfortunately, they didn't have the convenient character manipulation instructions found on the PDP-10, so programmers had to do shifts, masks, etc. Grumble.
-r
prev parent reply other threads:[~2021-02-03 21:10 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-02-03 14:55 M Douglas McIlroy
2021-02-03 20:07 ` John Cowan
2021-02-03 20:51 ` Lars Brinkhoff
2021-02-03 21:10 ` Rich Morin [this message]
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