Caches are essential to gain the maximum performance
from modern microprocessors
The performance of a cache is close to that of SRAM
but at the cost of DRAM
Caches can be used to form the basis of a parallel
computer
Bus-based multiprocessors do not scale well: max < 10
nodes
Larger-scale shared-memory multiprocessors require
more complicated networks and protocols
CC-NUMA is becoming popular since systems can be
built from commodity components (chips, boards, OSs)
and use existing software
e.g. HP/Convex, Sequent, Data General, SGI, Sun, IBM