CISC [Complex instruction set Computing]

It is very large instruction sets ,more than 300 separate instructions.

Performance was improved by allowing the simplification of program compilers.

The range of more advanced instructions available.

Expensive to produce.

More specialized addressing modes and registers also being implemented, with variable length instruction codes.

Instruction pipelining cannot be implemented easily.

Many complex instructions can access memory, such as direct addition between data in two memory locations.

Mainly used in normal PC’s, Workstations and servers.

CISC systems decrease execution time by reducing the number of instructions per program.

Example: Intel x86.

Advantages of CISC

  • Less size of program codes.
  • Compilers are simple.

Disadvantages of CISC

  • Implementation is very complex.
  • More power consumption.