TABLE OF CONTENTS We are all in the gutter, but some of us are looking at the stars.
Oscar Wilde
This chapter and the next explain the workings of processors with Intel EM64T at a comparatively low level. The chapters should be of interest primarily to programmers who need a good understanding of how the processor executes their programs. Developers who occasionally dip down to the level of assembly language are likely to find items here of special interest. However, developers who work exclusively with high-level languages or execution environments, such as Java and Microsoft's .NET, do not need much of the information these two chapters contain. If you use one of those managed environments, you can skip to reading the material in Chapters 7 through 9. However, you will find Chapters 7 through 9 more meaningful if you're familiar with the low-level architecture presented here.
Registers are special, high-speed locations in the processor where data items and addresses are placed for use by the processor in executing a specific instruction. Depending on the instruction, the architecture frequently requires that one or more operands be in a register prior to execution frequently all the operands must be. The term load/store operations is generally applied to the processes of moving data into registers (the load) and later back to memory (the store). Many of the instructions in a typical processor architecture are designed to make load/store operations as efficient as possible, due to their frequent use in all software.
Modern processors assign specific...
