Chapter 4. Superscalar Execution

Chapter 1 and Chapter 2 described the processor as it is visible to the programmer. The register files, the processor status word (PSW), the arithmetic logic unit (ALU), and other parts of the programming model are all there to provide a means for the programmer to manipulate the processor and make it do useful work. In other words, the programming model is essentially a user interface for the CPU.

Much like the graphical user interfaces on modern computer systems, there’s a lot more going on under the hood of a microprocessor than the simplicity of the programming model would imply. In Chapter 12, I’ll talk about the various ways in which the operating system and processor collaborate to fool the user into thinking ...

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