Superscalar Processors

Synonyms

Multiple-instruction issue; Out-of-order execution processors

Definition

A superscalar processor is designed to achieve an execution rate of more than one instruction per clock cycle for a single sequential program.

Discussion

Introduction

Superscalar processor design typically refers to a set of techniques that allow the central processing unit (CPU) of a computer to achieve a throughput of more than one instruction per cycle while executing a single sequential program. While there is not a universal agreement on the definition, superscalar design techniques typically include parallel instruction decoding, parallel register renaming, speculative execution, and out-of-order execution. These techniques are typically employed along with complementing design techniques such as pipelining, caching, branch prediction, and multi-core in modern microprocessor designs.

A typical superscalar processor today is the Intel Core i7 processor based on the Nehalem microarchitecture. There...