Path: utzoo!telly!attcan!ncrcan!scocan!seanf
From: seanf@sco.COM (Sean Fagan)
Newsgroups: comp.arch
Subject: Re: 64 bits--why stop there?
Message-ID: <1990Aug23.021909.14733@sco.COM>
Date: 23 Aug 90 06:19:09 GMT
References: <5539@darkstar.ucsc.edu> <13285@yunexus.YorkU.CA> <30728@super.ORG> <9660@ganymede.inmos.co.uk> <224@csinc.UUCP> <1263.26cdaecc@waikato.ac.nz> <6106@vanuata.cs.glasgow.ac.uk> <2437@crdos1.crd.ge.COM>
Reply-To: seanf@sco.COM (Sean Fagan)
Organization: The Santa Cruz Operation, Inc.
Lines: 28

In article <2437@crdos1.crd.ge.COM> davidsen@crdos1.crd.ge.com (bill davidsen) writes:
>  While we're all talking about 64 bits, where is it writ' that word
>size shall be a power of two bits? Outside of the prevalence of the
>eight bit byte, is there a good technical reason for it?

None.  Example:  CDC Cyber 170-state (ok:  everyone who knew I was going to
say that, raise your hand 8-)).  Very fast machine, RISC-type architecture,
designed by Seymour ``God'' Cray, etc.

It had 60-bits words (one's complement, even!).  It's OS, NOS, used 6-bit
characters, and could pack 10 of them to a word (btw:  word-addressing
*only*).

Addresses were 18-bits, and this, plus the above, allowed a nice little
thing:  a symbol name and its address could take up one word:  7 6-bit
``bytes'' for the name (since FORTRAN only allows 6, and NOS allowed 7), and
18 bits for the address.  Nice.

The sucessor to the 7600, the 8600, was to be a 64-bit machine (don't know
how many address bits, though), partially because the 60-bits was, even at
the time (late 60's to early 70's), causing some problems.  Also because
people wanted it, of course 8-).

-- 
Sean Eric Fagan  | "let's face it, finding yourself dead is one 
seanf@sco.COM    |   of life's more difficult moments."
uunet!sco!seanf  |   -- Mark Leeper, reviewing _Ghost_
(408) 458-1422   | Any opinions expressed are my own, not my employers'.