CPU: Central Processing Unit

CPU: Central Processing Unit

1. Function of the CPU and its Components

   • The purpose of the CPU is to process data. It is called the brains of the computer. The CPU has two main components.
     • One of those components is the Control Unit. This uses electrical signals to direct the system to execute instructions in stored programs.
       • The second one is the ALU which stands for the Arithmetic and Logic Unit. This carries out all maths and logic including: Adding, Subtracting and Comparisons

2. Fetch-Execute Cycle

   • When a computer is switched on, it starts an endless fetch-execute cycle.
     • The programs the CPU needs to process are stored in the main memory
     • The CPU fetches the instruction, decodes it and executes it before repeating this process.

3. Characteristics of CPU

   • The number of cores
     • The amount of cores in a CPU affects how fast it processes information.
       • A dual-core CPU has two CPU's working together. They fetch, decode and execute them at the same time meaning they can process more instructions.
   • Clock Speed
     • The clock-speed is how quickly the CPU processes. It is a vibrating crystal that maintains a constant rate.
       • The speed is measured in Hertz (Hz) or cycles per second. E.g: a clock speed of 500Hz would be 500 cycles per second.
         • GHz means billions of cycles per second. E.g: a speed of 3GHz would be 3 billion cycles per second.
   • Buses
     • Data is moved around the computer on buses. Their speed depends on how quickly the computer can process data.
       • A bus is a circuit that connects one part of the motherboard with another

4. Cache memory

   • Cache memory is so fast it can work almost as fast as the CPU, however it is very expensive and only is used to store data that is waiting to be processed by the CPU.
     • Cache memory is usually stored in much smaller sizes and it is located near the CPU to minimise access time.

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