CISC Vs RISC Achitectures

CISC Vs RISC

          The performance of a CPU is highly dependent on its internal architecture. Mainly there are two architectures. They are,

CISC Architecture

        

          CISC stands for Complex Instruction Set Computing. Traditional theory states that CPUs can be made quicker by adding more and more complexity into the instructions of the instruction set. This architecture can execute several low level operations such as load from memory, an arithmetic operations and a memory store all in a single instruction.
         CISC is the more advanced architecture compare with RISC architecture. It can multiply two logical numbers in one step. In CISC Architecture no of bits per instruction is high. That means it can have high capacity. CISC is used in computer Micro processors & the devices which have high speed processing power.

RISC Architecture

              RISC stands for Reduced Instruction Set Computing. It states that the best performance can be achieved by reducing the time taken to execute any given instruction. Rather than have complex instructions that require many clock cycles (more on this later) to complete, RISC chips use very simple instructions that could be performed in fewer clock cycles. Performance can then be improved by making the cycles shorter.

             Compare to CISC, RISC haven’t that much of process power. It can’t multiply two logical numbers in one step. It uses add and shift function to do that.

Multiply function

CISC Architecture-    00010110 + 00000110 = 1000100     ; It can multiply it one step.

RISC Architecture-   00010110 + 00000110 =?  But here we can’t do it in one step because it doesn’t have a multiplying function.

Therefore it uses add & shift