Processor

The processor is the part of the computer that fetches, decodes and executes a program’s instructions.

It’s the ‘brain’ of the computer, because it’s the part that tells all the other components what to do.

Role of the processor

• Executing the instructions of a program
  • It does this with the fetch-decode-execute cycle
• Managing the resources of the computer
• Handling user input, from the keyboard, mouse, etc.
• It basically connects all the other components together, and makes sure they work together to run the program.

Multi-thread processors

Pretty much every modern processor is multi-threaded. That means that it can be carrying out multiple instructions at the same time, if the program is written to allow it.

If a processor has multiple cores, then it basically has lots of processors connected together, so they can work at the same time. This is called parallel processing.

See: processor core.

What’s a processor made of?

Processors are made of tiny transistors, which are like tiny switches that can be turned on or off. The transistors are arranged so that they produce , which are the building blocks of the processor - we combine logic gates together to make more complex circuits.

Parts of the processor

• Control unit: This is the part of the processor that fetches instructions from memory, decodes them, and tells the other parts of the processor what to do.
• Arithmetic logic unit (ALU): This is the part of the processor that performs maths and boolean logic operations, like addition, subtraction, AND, OR, etc.
• Registers: These are small, fast storage locations within the processor, where it can store data and instructions that it’s currently working on. They’re much faster than the main memory, so the processor can access them quickly.
• Cache: This is a small amount of very fast memory that’s built into the processor. It’s used to store frequently accessed data and instructions, so the processor can access them quickly without having to go to the main memory. It’s like a ‘shortcut’ for the processor to access data it needs quickly.
• Clock: This is a tiny circuit that generates an on and off signal, lots of times per second at a regular frequency, which is used to synchronise the operations of the processor. It basically tells the processor when to do things, and how fast to do them. The speed of the clock is measured in hertz (Hz), and it tells us how many instructions the processor can execute per second.
• Bus: This is a set of wires that connects the different parts of the processor together, and allows them to communicate with each other. It carries data, instructions, and control signals between the different parts of the processor.

See processor components.