CYBER word length

Robert Reed bobr at zeus.UUCP
Wed Nov 12 06:02:56 AEST 1986


In article <612 at astroatc.UUCP> philm at astroatc.UUCP (Phil Mason) writes:
>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.

That's a great myth.  Almost believable.  But isn't it true that the Cyber
word length was set a 60 bits to be compatible with the old CDC-6000 series?
Isn't the operant concern here to be a multiple of 6?  See, when the 6000
was born, it was a successor of the CDC-3300 series, which used 36 bit words
(like many contemporaries, such as Univac and Honeywell and DEC).  Back in
those days, most systems used 6 bit codes for characters, and DEC for
example, had machines with word sizes of 12 (PDP-8) and 18 (LINC/PDP-15)
bits.  If anything, the reason for 60 bits is historical precedent.
-- 
Robert Reed, Tektronix CAE Systems Division, bobr at zeus.TEK



More information about the Comp.unix.wizards mailing list