The Purpose of The CPU

The purpose of the CPU is to control both hardware and software to the user, provide an interface (hiding the complex systems), and to manage memory. To do this, an Architecture needs to be used to allow the CPU to understand how to process the instructions within the device.

Purpose of the CPU - fetch decode execute

The tasks that the CPU performs can be broken down into Fetch, Decode, and Execute. This is referred to as the Fetch Execute Cycle and allows your computer to function.

Imagine your CPU like your brain in the classroom:

  • You arrive and are given a list of tasks
  • You select (fetch) the first task
  • You work out (decode) what you are being asked to do
  • You get any data that the task needs
  • You perform (execute) the task
  • Then you move on to the next task

The CPU in your computer can vary in size and power, but most work in the same way. Back in 1965, Gordon Moore published a paper predicting that processors would halve in size and double in processing power every two years – this is called Moore’s Law and remained accurate right up until the last few years. In fact, this exponential growth actually happened every 18 months for many years. This is why we can wear a watch that now has more processing power than the spacecraft used for the first moon landings!

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