Central Processing Unit

What is a Central Processing Unit?

central processing unit (CPU) is the electronic circuitry within a computer that carries out the instructions of a computer program by performing the basic arithmetic, logical, control and input/output (I/O) operations specified by the instructions. The term has been used in the computer industry at least since the early 1960s.[1] Traditionally, the term "CPU" refers to a processor and its control unit (CU), distinguishing these core elements of a computer from external components such as main memory and peripherals.[2]

The form, design and implementation of CPUs have changed over the course of their history, but their fundamental operation remains almost unchanged. Principal components of a CPU include the arithmetic logic unit (ALU) that performs arithmetic and logic operations, hardware registers that supply operands to the ALU and store the results, and the control unit that fetches instructions from the main memory, and decodes and executes them while relying on the ALU and registers as necessary to perform decomposed operations.

Most modern CPUs are microprocessors, meaning they are contained on a single integrated circuit (IC) chip. An IC that contains a CPU may also contain memory, peripheral devices, and other components of a computer; such devices are variously called microcontrollers or systems on a chip (SoC). Some computers have multi-core processors with two or more CPUs (which are then called "cores") within a single chip. On the other hand, array processors or vector processors have multiple processors that operate in parallel, with no one unit considered central.