CPU is an abbreviation of Central Processing Unit, and pronounced as separate letters. The CPU is the brains of the computer, sometimes referred to simply as the Processor or Central Processor. The CPU is where most calculations take place. In terms of computing power, the CPU is the most important element of a computer system, although with regards to games, the GPU holds prestige, too.

On large machines, CPUs require one or more printed circuit boards. On personal computers and small workstations, the CPU is housed in a single chip called a Microprocessor.

A CPU performs three basic operations on data: It reads data, It manipulates data, and it writes data. In simple terms, the CPU needs only four elements to process data:

Instructions, Instruction Pointers, Registers, and the ALU.

  • The Instruction Pointer tells the CPU where in Memory the instuction it needs to run is located.
  • The Registers are temporary storage areas on the CPU itself, and can be used for storing data that either needs to be processed, or data that has already been processed.
  • The The Arithmetic Logic Unit, or ALU, is essentually the CPU's mathematical calculator, performing math and logic functions dictated by the Instructions.

The CPU consists of some additional parts that help the basic parts do their jobs:

  • The Instruction Fetch grabs instructions from RAM or an area of memory located on the CPU, such as the cache.
  • The Instruction Decoder takes the instruction from the fetch and translates it so the CPU understands. It then determines what steps are necessary to accomplish that instruction.
  • The Control Unit manages and coordinates all the operations of the chip. It lets the ALU know when to calculate, tells the fetch when to grab a value, and tells the decoder when to translate the value into an instruction.

It sounds incredible, but a ZX81 can still process the same data that a 3.8GHz Pentium 4 can. You would just die of old age waiting for the ZX81 to finish.

There are two main companies who produce processors for the Consumer Market. The first, and possibly the most well known, is Intel. The second is AMD, also known as Advanced Micro Devices. VIA also makes processors, as did Cyrix.

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