SISD

Single Instruction streams, Single Data streams tend to be your uniprocessor systems. These systems have one sequential stream of data coming into them, and one single processing unit that is used to execute this stream.

This style of architecture typically represents your classical Von Neumann machines, and for a vast number of years, before multi-core processors became popular, this represented your typical home computer. You would have a single processor that handled everything you required. These would, however, be incapable of things such as instruction parallelism and data parallelism, and things such as graphics processing were incredibly taxing on these systems.

The following figure shows an overview of how a uniprocessor system looks. It features one data source that is processed by a single processing unit:

This style of architecture features all of the advantages and disadvantages that we outlined earlier in the chapter when we covered single-core processors.

An example of a uniprocessor could be the Intel Pentium 4.