CYBER word length

[capshaw at milano.UUCP]

Annals of the History of Computing, Vol. 2, No. 4 (October 1980)
contains the  article ''The CDC 6600 Project'' by James E. Thornton.  
In the article Thornton writes

	It was my good fortune to design the 6600 CPU.  [Seymour]
	Cray and I established a clean, simple, and logically very
	powerful instruction set, biased to scientific and binary
	processing.  ...  The selection of 60-bit word length came
	after a lengthy investigation into the possibility of 64 bits.
	Without going into to it in depth, our octal background got the
	upper hand.  Another aspect of the 60-bit word, though, was how
	efficiently the small instruction format (15 bits) and the
	large instruction format (30 bits) fit.  I have long felt that
	a sixteenth bit would have demolished our clean and simple
	instruction set.  We were not ready for the vector and array
	processing to come much later.  We were also not from the the
	school of variable-length string processing.


-- 
Dave Capshaw