Host Computer: An array processor may be attached to a host computer by the control unit. The reason of the host computer is to broadcast a sequence of vector instructions by CU to the PEs. Therefore, the host computer is a general-purpose machine that acts as a manager of the full system.

Array processors are special purpose computers which have been adopted for the following:

• various scientific applications,
• matrix algebra,
• matrix eigen value calculations,
• real-time scene analysis

SIMD array processor on the big scale has been developed by NASA for earth resources satellite image processing. This computer has been named extremely parallel processor (MPP) because it haves 16,384 processors that do work in parallel. MPP gives real- time time varying scene analysis.

Though, array processors are not commercially popular and are not usually used. The reasons are that array processors are complex to program compared to pipelining and there is difficulty in vectorization.