Array Processing | Computer Architecture & Organisation (CAO) - Computer Science Engineering (CSE) PDF Download

Array Processing

• An array processor is a processor that performs computations on large arrays of data.
• The term is used to refer to two different types of processors.
  • Attached array processor:
    • Is an auxiliary processor.
    • It is intended to improve the performance of the host computer in specific numerical computation tasks.
  • SIMD array processor:
    • Has a single-instruction multiple-data organization.
    • It manipulates vector instructions by means of multiple functional units responding to a common instruction.

Attached Array Processor

• Its purpose is to enhance the performance of the computer by providing vector processing for complex scientific applications.
  • Parallel processing with multiple functional units
• Fig. 4-14 shows the interconnection of an attached array processor to a host computer.
• For example, when attached to a VAX 11 computer, the FSP-164/MAX from Floating-Point Systems increases the computing power of the VAX to 100megaflops.
• The objective of the attached array processor is to provide vector manipulation capabilities to a conventional computer at a fraction of the cost of supercomputer. 

SIMD Array Processor

• An SIMD array processor is a computer with multiple processing units operating in parallel.
• A general block diagram of an array processor is shown in Fig. 9-15.
  • It contains a set of identical processing elements (PEs), each having a local memory M.
  • Each PE includes an ALU, a floating-point arithmetic unit, and working registers.
  • Vector instructions are broadcast to all PEs simultaneously.
• Masking schemes are used to control the status of each PE during the execution of vector instructions.
  • Each PE has a flag that is set when the PE is active and reset when the PE is inactive.
• For example, the ILLIAC IV computer developed at the University of Illinois and manufactured by the Burroughs Corp.
  • Are highly specialized computers.
  • They are suited primarily for numerical problems that can be expressed in vector or matrix form.