[ The PC Guide | Systems and Components Reference Guide | The Processor | Processor Architecture and Operation ]

Internal Processor Architecture and Operation

The architecture of a processor describes its internal structures and how it works. These are logical structures of course; all processors are made of semiconductor material, and it is how this is arranged that determines how the processor will work. This is similar to how it is with software: all software boils down to a long string of ones and zeros, but it is how you design and lay out those bits that determines whether the software is good or not.

Processors are in some ways "black boxes". They all perform the same basic function to the outside world: they process instructions. In fact, the instructions they support, at least in the PC world, haven't changed much in the last 10 years. But on the inside, the ways they use to execute instructions have grown much more powerful and complicated. In addition to improving performance by "brute force" (increasing clock speeds) chip makers have found innovative ways to wring more performance from each clock cycle. For example, the Intel 486DX-25 has over twice the performance of the Intel 386DX-25, even though they run at the same clock speed. The improvement in this 486's power is entirely due to advancements in internal architecture.

Furthermore, the architecture has an impact on how fast the processor can run. Since a faster processor means a shorter time for each clock cycle, it becomes more and more difficult to design circuitry that can work in these smaller amounts of time. Making processors run at faster clock speed necessitates changes not just to its physical characteristics but its internal logic design as well.

Next: Processor Instruction Sets

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