Introduction to CPUs

What is it? Edit

A CPU stands for Central Processing Unit. The main job of the CPU is to run the computer programs and boss around the other parts of the computer (Video card or RAM ect).The basic CPU has four basic commands that it uses to control the rest of the computer they are:fetch, decode, execute, and writeback. Fetch is used to find things like documents within the computer's hard drive or commands when you double click on a desktop icon. Decode is used to break down the steps of the coding so that the CPU can more easily process the data it is meant to compute. Execute, as its name suggests runs the program that the CPU has been assigned to do. Finally writeback inputs the results of the CPU after it has executed a program into the hard drive. CPUs are found in any types of computers, and can vary from a simple digital clock chip to the IBM super computer.

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  1. Control Unit
  2. Arithmetic Logic Unit
  3. System Bus
  4. Cache
  5. Registers

The following information is not required. We need to explain what the CPU does, not its history.

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Control UnitEdit

The control unit is the circuitry that controls the flow of data through the processor, and coordinates the activities of the other units within it. In a way, it is the "brain within the brain", as it controls what happens inside the processor, which in turn controls the rest of the PC. The control unit order the other parts of the CPU to do the acts of fetching, decoding, managing execution and then storing results. So as said above it is like a "brain within the brain" for it coordinates many of the activities that the CPU needs to do.

Arithmetic Logic UnitEdit

The Arithmetic Logic Unit (ALU) is a digital circuit that performs arithmetic and logical operations. Its tasks can vary from simple keeping a timer in place or to complex ones like calculating advanced physic results.

System BusEdit

The front side bus (FSB) is the data connection that carries data from the computer components to the CPU. The faster your FSB the faster the data will get transfered from one part of the computer to the next.


"The central processing unit contains a number of memory locations which are individually addressable and reserved for specific purpose. These memory locations are called registers. Some of theses registers are accessible to the programmer while some others are for the exclusive use of CPU. This latter set of registers is used for storage, interpretation and execution of instructions and the intermediate results. Total number of these registers varies among different computers. Widely used microprocessors have got eighteen 32-bit data registers which are used for storing instructions and operand of various sizes. One of these seven are 32-bit general purpose registers." from