the age of the dinosaurs

Differences between scalar and superscalar processors generally boil down to quantity and speed. A scalar processor, considered to be the simplest of all processors, works on one or two computer data items at a given time. The superscalar processor works on multiple instructions and several groups of multiple data items at a time. Scalar and superscalar processors both function the same way in terms of how they manipulate data, but their difference lies in how many manipulations and data items they can work on in a given time. Superscalar processors can handle multiple instructions and data items, while the scalarprocessor simply cannot, therefore making the former a more powerful processor than the latter.

Scalar and superscalar processors both have some similarities with vector processors. Like ascalar processor, a vector processor also executes a single instruction at a time, but instead of just manipulating one data item, its single instruction can access multiple data items. Similar with the superscalar processor, a vector processor has several redundant functional units that let it manipulate multiple data items, but it can only work on a single instruction at a time. In essence, a superscalar processor is a combination of a scalar processor and a vector processor.

A superscalar architecture requires an on-board hardware scheduler which typically runs at twice the clock frequency and consumes a large amount of power. In contrast, VLIW scheduling is done by the compiler and no hardware scheduler is required therefore the power requirements tend to be lower.

Superscalar machines execute regular

sequential programs. The programmer is

unaware of the parallelism.

Superscalar processors have a main processor that can take only one command at a time. It has direct connections to the secondary systems of the processor that feeds information right into subsystems to execute specific commands and output information separate. There is only one type of superscalar processor but there are scalar processors and vector processors.