CISC and RISC architecture

There are two types of architecture in embedded system. They are RISC and CISC architecture. Let us understand the difference between those two.

CISC (Complex Instruction Set Computer) architecture 

  • Complex and not simple
  • Different instruction of different format
  • Different instruction of different length
  • Different addressing modes
  • Requires multiple cycles for execution
  • The advantages of the CISC architecture are that many of the instructions are macro-like, allowing the programmer to use one instruction in place of many simpler instructions Those from Intel's Pentium processors are referred to as CISC because they have a full and comprehensive instruction set

RISC (Reduced Instruction Set Computer) architecture

  • It is simple and easy
  • Smaller chip
  • Smaller pin count
  • Low power consumption
  • Each instruction of fixed length
  • Facilitates instruction pipe lining
  • Load general purpose register set
  • Load store architecture
  • Consumes less machine cycle
  • Those from IBM, powering their RS6000 mini-computers, are RISC - Reduced Instruction Set