Computers as Components, 2nd Edition

7.2 CPUs and Accelerators 357

An accelerator is not a co-processor.A co-processor is connected to the internals

of the CPU and processes instructions as defined by opcodes. An accelerator inter-

acts with the CPU through the programming model interface; it does not execute

instructions. Its interface is functionally equivalent to an I/O device, although it

usually does not perform input or output.

Both CPUs and accelerators perform computations required by the specification;

at some level we do not care whether the work is done on a programmable CPU or

on a hardwired unit.

The first task in designing an accelerator is determining that our system actually ...