CPU – Central Processing Unit

CPU (pronounced as separate letters) is the abbreviation for central processing unit. Sometimes referred to simply as the central processor, but more commonly called processor, the CPU is the brains of the computer where most calculations take place. In terms of computing power, the CPU is the most important element of a computer system.

Components of a CPU

The two typical components of a CPU include the following:

  • The arithmetic logic unit (ALU), which performs arithmetic and logical operations.
  • The control unit (CU), which extracts instructions from memory and decodes and executes them, calling on the ALU when necessary.

Image: Relationship between the elements of the CPU, input and output, and storage (see study guide).

Printed Circuit Boards, Microprocessors

On large machines, the CPU requires one or more printed circuit boards. On personal computers and small workstations, it is housed in a single chip called a microprocessor. Since the 1970’s the microprocessor class of CPUs has almost completely overtaken all other CPU implementations.

The CPU itself is an internal component of the computer. Modern CPUs are small and square and contain multiple metallic connectors or pins on the underside. The CPU is inserted directly into a CPU socket, pin side down, on the motherboard.

Each motherboard will support only a specific type (or range) of CPU, so you must check the motherboard manufacturer’s specifications before attempting to replace or upgrade a CPU in your computer. Modern CPUs also have an attached heat sink and small fan that go directly on top of the CPU to help dissipate heat.

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