[comp.arch] What is a coprocessor... and is the i860 one?

mslater@cup.portal.com (Michael Z Slater) (08/31/89)

There has been a lot of discussion about whether or not the i860 was
really designed as a coprocessor.  This has caused a lot of confusion
among those who think of a coprocessor as something like a 387, which
operates from the same instruction stream as the 386 and cannot operate
standalone.  If THAT is what a coprocessor is, then the i860 certainly
is not one.

However, the term coprocessor is often used to mean any processor other
than the main processor, regardless of how it gets its instructions or
how it interfaces to the main processor.  In my opinion, something should
only be called a coprocessor if it fetches instructions from the same
stream as another processor, transparently extends the instruction set of
that processor, and cannot operate as a stand-alone processor.

This brings up two questions: