4. Parallel Computing 14. Introduction

14.6 Data-Parallel Machines

We next turn our attention to the realization of parallelism on actual computers. There are

two general classes of machines for this purpose: data-parallel machines and control-

parallel machines. Each of these classes can be sub-divided further. Furthermore, each

class of machines can simulate the other, although one kind of machine will usually be

preferred for a given kind of problem.

Data parallel machines can be broadly classified into the following:

SIMD multiprocessors

Vector Processors

Cellular Automata

SIMD Multiprocessors

"SIMD" stands for "single-instruction stream, multiple data stream". This means that

there is one stream of instructions controlling the overall operation of the machine, but

multiple data operation units to carry out the instructions on distinct data. The general

structure of a SIMD machine can thus be depicted as follows:

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Parallel Computing

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Control 

Processor

Control 

Program 

Memory

Data 

Processor

Data 

Memory

Data 

Processor

Data 

Memory

Data 

Processor

Data 

Memory

Data 

Processor

Data 

Memory

....