X86 Architecture

Intel’s Dilemma• All (most) software uses CISC code and needs a CISC ISA

• RISC is more efficient, CISC is cumbersome

PentiumCISC Input machine code

Translation CISC to RISC

Execution as RISC

PentiumArchitecture

CISC

RISC

Pentium Pipeline

// Test1.cpp : Defines the entry point for the console application.//#include "stdafx.h"int _tmain(int argc, _TCHAR* argv[]){

int x,y,z;x = 3;

0041137E mov dword ptr [x],3 puts 3 into memory at address x

y = 5;00411385 mov dword ptr [y],5 puts 5 into memory at address y

z = x + y;0041138C mov eax,dword ptr [x] moves data at address x into eax0041138F add eax,dword ptr [y] adds data at address y to eax00411392 mov dword ptr [z],eax moves contents of eax to memory at y

return 0;00411395 xor eax,eax }