Multiprocessing

What is multiprocessing?

Multiprocessing is a term applied for interconnecting two or more central processing units in a single computer. Multiprocessing operating systems facilitates several programs to run simultaneously. It Shares the instruction execution process thus increasing computing power.

For example a computer can have two processors with one performing the task of editing input and output from terminals (Front End Processing) and the other handling processing of data.

Characteristics of Multiprocessors

1. Parallel computing - Simultaneous use of multiple processors, all components of a single architecture to solve a task.
2. Distributed computing - use of a network of processors. Each capable of being viewed as a computer in its own right, to solve a problem. Processors may be heterogeneous, multi user; usually individual task is assigned to a single processor.
3. Concurrent computing - all of the above.
4. Super computing - use of fastest, biggest machines to solve big, computationally intensive problems.
5. Pipe lining - breaking a task into steps performed by different units.
6. Vector computing - used in operations such as multiple broken into several steps.
7. Systolic - similar to pipe lining but units are not necessarily arranged linearly, steps are typically small and more numerous performed in lockstep fashion.

Parallel Processor Systems

What are parallel processor systems?

In computers, parallel processing is the processing of program instructions by dividing them among multiple processors with the objective of running a program in less time.In the earliest computers, only one program ran at a time. A computation-intensive program that took one hour to run and a tape copying program that took one hour to run would take a total of two hours to run. An early form of parallel processing allowed the interleaved execution of both programs together. The computer would start an I/O operation, and while it was waiting for the operation to complete, it would execute the processor-intensive program. The total execution time for the two jobs would be a little over one hour.

Types of parallel processor systems

There are four types of parallel processor systems.

• Single Instruction Single Data stream (SISD)
• Single Instruction Multiple Data stream (SIMD)
• Multiple Instruction Single Data Stream (MISD)
• Multiple Instruction Multiple Data stream (MIMD)