Difference Between RISC and CISC


In this post, we will understand the difference between RISC and CISC −

Microprocessors are classified based on the architecture (instruction set) into RISC and CISC.


  • It stands for Reduced Instruction Set Computer.

  • It is a microprocessor architecture that uses small instruction set of uniform length.

  • These simple instructions are executed in one clock cycle.

  • These chips are relatively simple to design.

  • They are inexpensive.

  • The disadvantage is that the computer has to repeatedly perform simple operations in order to execute a large program that has a large number of processing operations.

  • Examples of RISC chips include SPARC, POWER PC.

  • It has less number of instructions.

  • It has fixed-length encodings for instructions.

  • Simple addressing formats are supported.

  • It doesn’t support arrays.

  • It doesn’t use condition codes.

  • Registers are used for procedure arguments and return addresses.

Architecture of RISC:


  • It stands for Complex Instruction Set Computer.

  • This offers hundreds of instructions of different sizes to the users.

  • This architecture has a set of special purpose circuits which help execute the instructions at a high speed.

  • The instructions interact with memory using complex addressing modes.

  • These processors reduce the size of the program.

  • Consequently, they take less number of memory cycles to execute the programs.

  • The overall speed of execution is high.

  • Examples of CISC include Intel architecture, AMD.

  • It has variable-length encodings of instructions.

  • It supports array.

  • It has a large number of instructions.

  • Arithmetic and logical operations can be applied to memory and register operands.

  • Condition codes are used.

  • The stack is used for procedure arguments and return addresses.

Architecture of CISC

Updated on 29-Apr-2021 09:03:05