--- Brian Cole wrote:
PS.  As I recall, the quadra650 has a 33MHz CPU while the centris650 has a
25MHz CPU.  The quadra610 has a 25MHz CPU while the centris 610 has a 20MHz
CPU.  The centris 660av was renamed the quadra 660av without changing the CPU
speed.  (Apple has taken to doubling these MHz numbers as of late.)
--- end of quoted material ---

This is due to the fact that on most any computer with a processor and a bus,
macs included of course, the bus runs exactly half as fast as the processor.
Apple simply took to using the macs' processor speeds instead of their bus
speeds in its advertising numbers. I'd be inclined to think that the reasons
for this have to do with the long-standing slow-mac perception... but the
reasons for it are neither here nor there I suppose. In any case that's what
the number change is about.

Cheers,

Stephen