__Coprocessor__

A special-purpose processing unit
that assists the CPU in performing certain types of operations. For example, a
math coprocessor performs mathematical computations, particularly
floating-point operations. Math coprocessors are also called numeric and
floating-point

coprocessors.

Some computers come with
coprocessors built in. For others, you can add a coprocessor. A math
coprocessor can increase a computer's speed and power dramatically,
particularly if you are running programs that perform a lot of floating-point
arithmetic (engineering and scientific applications, statistical analysis, and
graphics). Note, however, that the program itself must be written to take
advantage of the coprocessor. If the program contains no coprocessor
instructions, the coprocessor will never be utilized.

In addition to math coprocessors,
there are also graphics coprocessors for manipulating graphic images. These are
often called accelerator boards.