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Flynn’s Classification of Computers

M.J. Flynn proposed a classification for the organization of a computer system by the number of instructions and data items that are manipulated simultaneously.

The sequence of instructions read from memory constitutes an instruction stream.

The operations performed on the data in the processor constitute a data stream.

Note: The term ‘Stream’ refers to the flow of instructions or data.

Parallel processing may occur in the instruction stream, in the data stream, or both.

Flynn’s classification divides computers into four major groups that are:

1. Single instruction stream, single data stream (SISD)
2. Single instruction stream, multiple data stream (SIMD)
3. Multiple instruction stream, single data stream (MISD)
4. Multiple instruction stream, multiple data stream (MIMD)