6809 SBC (was Editor religious wars (was Re: Museums))
ard at p850ug1.demon.co.uk
Mon Feb 1 13:46:16 CST 2010
> > 16 bits, actually. The two MMU architectures extended that to 18 and
> > 22 bits. I wouldn't call it a goof considering the first one came
> > out in 1970. For a small lab minicomputer in 1970, 64KB isn't bad at
> > all.
> Considering the cost of CORE memory in 1970, 64KB was
> much larger than any PDP-11 at that time. 8KB was a
> common system. Even up to around 1975, I don't think
> there was an MMU available in any case. Does anyone
> know when the MMU was first used with more than 64KB
> of memory for the system?
The MMU appears to have been planned from the very start, if only because
18 address lines were dedined on the Unibus.
AFAIK the first machien to have an (optional) MMU was the 11/45 which
came out in 1972. I don't know whne the MMU itself came out, but the
backplne was designed to take it fro mthe very start (there were
considerable changes at S/N2000 in the 11/45, and even machines before that
serial number could take the MMU).
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