6809 SBC (was Editor religious wars (was Re: Museums))

1 Feb 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).

-tony

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6809 SBC (was Editor religious wars (was Re: Museums))