CISC vs RISC

• CISC & RISC 

  • A computer processor will have an instruction set that it can use to execute programs 
  • This will vary from one processor to the next 
  • There are 2 types of processors: 
  • Complex Instruction Set Computer  
  • Reduced Instruction Set Computer 
• CISC (Complex Instruction Set Computer) 

  • Complex Instruction Set Computer (CISC) consists of a larger instruction set which includes more complex instructions 
  • As the instructions are more complex, they can take more than one clock cycle to execute 
  • Has more general purpose registers 
  • Instructions take up less space in memory 
  • Is usually used in laptops and desktop computers 
• RISC (Reduced Instruction Set Computer) 

  • Reduced Instruction Set Computer consists of a smaller instruction set with more simple instructions 
  • Each instruction takes one clock cycle to execute which makes it more suitable for pipelining 
  • Compilers are more complicated so will generate more instructions 
  • Has fewer addressing modes 
  • Is usually used in smartphones and tablets 
• What’s the Difference Between RISC & CISC? 

  
• RISC vs CISC processors

  • A program that has been written for a RISC processor won’t work on a CISC processor and vice versa 
  • A program that has been written for a RISC processor won’t necessarily work on another RISC processor as they may have different instruction sets