CISC

In computing, a term referring to the design of the central processing unit (CPU) and its instruction set. CISC computers are characterized by having large numbers of instructions, varying a lot in size and complexity. Usually, the various stages of instruction execution are followed, and only when all the stages have been finished can a new instruction start to be executed. RISC CPUs, by comparison, usually have few instructions in the instruction set, and the instructions are smaller and simpler. Complex problems are solved by executing several of the smaller instructions.

RISC CPUs often outperform CISC designs because the instructions are executed in a pipeline, which is analogous to a factory assembly line. The pipeline enables the execution of instructions to be overlapped, with the first stages of instruction taking place before the final stages of the previous instruction have been completed.