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From: baxter@milano.UUCP
Newsgroups: comp.arch
Subject: Re: *Why* do modern machines mostly have 8-bit bytes?
Message-ID: <4957@milano.UUCP>
Date: Wed, 22-Jul-87 09:40:51 EDT
Article-I.D.: milano.4957
Posted: Wed Jul 22 09:40:51 1987
Date-Received: Fri, 24-Jul-87 04:23:41 EDT
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Sender: baxter@milano.UUCP
Organization: MCC, Austin, TX
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Summary: Variable bit size machines


I agree, there doesn't seem to be anything magic about 8 bits.

If I remember right, the Burroughs 1700 was a microprogrammed machine
in which the macroinstruction set (there were several, one per
programming language) treated the memory as if it had different
bit sizes.  The sizes chosen were based pretty much on the expected
size of data operands, and on what was effectively a Huffman encoding
of the particular macroinstruction set.  The microarchitecture
did have a fixed size word, with a fancy field extractor used by
the microcode to get a the size chunks it wanted.


-- 
-- Ira Baxter     Microelectronics and Computer Technology Corporation
(512) 338-3795    3500 West Balcones Center Drive, Austin, Texas 78759