Inside Pentium 4 Architecture
 

In this tutorial we will explain you how Pentium 4 works in an easy to follow language. You will learn exactly how its architecture works so you will be able to compare it more precisely to previous processors from Intel and competitors from AMD..........................

Figure 6 you have a complete list of the kinds of instructions each execution unit deals with. FXCH and LEA (Load Effective Address) are two x86 instructions. Actually Intel’s implementation for FXCH instruction on Pentium 4 caused a great deal of surprise to all experts, because on processors from previous generation (Pentium III) and processors from AMD this instruction can be executed at zero clock cycle, while on Pentium 4 it takes some clock cycles to be executed.

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