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Path: utzoo!mnetor!seismo!uwvax!astroatc!philm
From: philm@astroatc.UUCP (Phil Mason)
Newsgroups: comp.unix.wizards
Subject: Re: CYBER word length
Message-ID: <612@astroatc.UUCP>
Date: Mon, 10-Nov-86 16:45:57 EST
Article-I.D.: astroatc.612
Posted: Mon Nov 10 16:45:57 1986
Date-Received: Mon, 10-Nov-86 21:40:49 EST
References: <7208@elsie.UUCP> <5142@brl-smoke.ARPA> <2447@hcr.UUCP> <363@yabbie.rmit.oz>
Reply-To: philm@astroatc.UUCP (Phil Mason)
Organization: Astronautics ATC, Madison, WI
Lines: 25

In article <363@yabbie.rmit.oz> rcodi@yabbie.rmit.oz (Ian Donaldson) writes:
>In article <2447@hcr.UUCP>, mike@hcr.UUCP (Mike Tilson) writes:
> . . .
>The CDC Cyber 170 series uses this concept to advantage with most languages;
>since it has 60-bits (a silly number, I agree), it sets all 'bss' storage to
>0600000000000004nnnnn, where nnnnnn is the address of the storage.  
> . . .
>Ian Donaldson.

The Cyber word length was selected to be 60 bits because of the number of 
exact divisors it has : 2, 3, 4, 5, 6, 10, 12, 15, 20, and 30. As you can 
see, one can pack quite a variety of different length data fields in one word
and not have to worry about your 3 (or whatever) bit fields from extending 
over a word boundary! CDC thought that nobody would ever use more than 64
different symbols for I/O so they made their "byte" six bits long.  Packing
ten of them in a word is convenient, to say the least.

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Kirk  : Bones ?                |  Phil Mason, Astronautics Technology Center
Bones : He's dead Jim.         |  Madison, Wisconsin - "Eat Cheese or Die!"
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