The Unabridged Pentium 4 IA32 Processor Genealogy

Processor = Instruction Fetch/Decode/Execute Engine

The processor's role in the system is really quite simple: it is an engine designed to fetch instructions from memory, decode them, and execute them. Figure 1-1 on page 13 illustrates a minimalist processor design. It consists of the following entities:

• Instruction Fetcher. The fetcher is responsible for tracking where (in memory) the next instruction is to read from. It issues memory read transaction requests to the Front Side Bus (FSB) Interface Unit which then reads the instructions from system memory.

• Instruction Decoder. It is responsible for decoding the instructions fetched from memory. The decoder translates the instructions into a form that can be directly executed by the execution ...