Lesson 1 : Types of Parallel Processing
1.1. Learning Objectives
On completion of this lesson you will be able to :
i) classify different types of parallel processing techniques.
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Traditionally, the computer has been viewed as a sequential machine.
Most computer programming languages require the programmer to
specify algorithms as sequences of instructions. CPUs execute programs
by executing machine instructions in a sequence and one at a time. Each
instruction is executed in a sequence of operation (fetch instruction,
fetch operands, perform operation, store results).
This view of the computer has never been entirely true. At the microoperation
level, multiple control signals are generated at the same time.
Instruction pipelining, at least to the extent of overlapping fetch and
execute operations, has been around for a long time. Both of these are
examples of performing functions in parallel.
When a computer application requires a very large amount of
computation that must be completed in a reasonable amount of time, it
becomes necessary to use machines with correspondingly large
computing capacity. Such machines are called supercomputers. Typical
applications that require supercomputers include weather forecasting;
simulation of large, complex, physical systems; and computer-aided
design (CAD) using high-resolution graphics.
As a general quantitative measure, a supercomputer should have the
capability to execute at least 100 million instructions per second.
In the development of powerful computers, two basic approaches can be
followed. The first possibility is to build the system around a highperformance
single processor, and to use the fastest circuit technology
available. Architectural features such as multiple functional units for
arithmetic operations, pipelining, large caches, and separate buses for
instructions and data can be used to achieve very high throughput. As the
design is based on a single processor, the system is relatively easy to use
because conventional software techniques can be applied.
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