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From: rick@seismo.CSS.GOV (Rick Adams)
Newsgroups: comp.unix.wizards
Subject: Re: CYBER word length
Message-ID: <42073@beno.seismo.CSS.GOV>
Date: Wed, 12-Nov-86 23:59:38 EST
Article-I.D.: beno.42073
Posted: Wed Nov 12 23:59:38 1986
Date-Received: Thu, 13-Nov-86 02:43:55 EST
References: <4169@amdahl.UUCP> <254@bsdpkh.UUCP>
Organization: Center for Seismic Studies, Arlington, VA
Lines: 27
Summary: fairly authoritative answer

From: "Assembly Language Programming for the Control Data 6000
	Series and the Cyber 70 Series" by Ralph Grishman, 
	Algorithmics Press, 1974, page 39

	As mentioned eariler, each word has 60 bits, relatively
	large as machine word sizes go. This size permits a floating
	point number with about 15 decimal places accuracy, sufficient for
	virtually all applications. A large word also permits several
	instructions to be put into one word, so that the number of
	memory accesses required toget out instructions is reduced. 
	Finally, 60 is a multiple of 2, 3, 4, 5, and 6, so that several
	different subdivisions of the word may be conveniently made.


It is also interesting to note later on page 43:

	Though 71 instructions isn't very many (most very large
	computers have several hundred), the 6600 instructions are
	sufficiently versatile and powerful and so fast that the
	6600 can run circles around many other large computers with
	many more instructions. Often an entire program loop on a
	6600 will be faster than a single instruction on another machine
	that performs the same calculation!

So, the CDC 6600 was a RISC machine!

---rick