RISC

Exercise: execute the following instruction using all
previous format:
1- X = (A + B)* (C + D)
2- S = F-(C*B)+M
3- N= (A+B*C)/ (F*E)

The design of computers either Cisc be or Risc depending on instruction set performed by the computer. The main differences between RISC and CISC are summarized by the following table:
Risc Computers Cisc Computers
Relatively few instructions large
Relatively few addressing mode Large No. of addressing mode
Fixed length of instruction Variable length of instruction
Decoding process is very simple Decoding process depends on instruction nature.
The operands must be in the registers The operands could be in the memory
Example: Apple hardware Example :Hardware of the Intel
Modern processors are pretty much all RISC, so, in this lecture we focus on RISC.
5-1 RISC ( Reduce Instruction Set Computer )

The new properties of Risc like (fixed length of inst., limited addressing mode, the Presence (وجود) of operand in the register ) added new Features for Risc :-