CYBER word length
Rick Adams
rick at seismo.CSS.GOV
Thu Nov 13 14:59:38 AEST 1986
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
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