 The Central Processing Unit CPU is the electronic circuitry within a computer that carries out the instructions of a computer programmed by performing the basic arithmetic, logical, control and input slash output I slash O operations specified by the instructions. The computer industry has used the term Central Processing Unit at least since the early 1960s. Traditionally, the term CPU refers to a processor, more specifically to its processing unit and control unit. See you distinguishing these core elements of a computer from external components such as main memory and I slash O circuitry. 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, processor registers that supply operands to the ALU and store the results of ALU operations and control unit that orchestrates the fetching from memory and execution of instructions by directing the coordinated operations of the ALU registers and other components. 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 interfaces, and other components of a computer. Such integrated devices are variously called microcontrollers or systems on a chip social. Some computers employ a multi-core processor, which is a single chip containing two or more CPUs called cores in that context, one can speak of such single chips as sockets. Array processors or vector processors have multiple processors that operate in parallel, with no unit considered central. There also exists the concept of virtual CPUs which are an abstraction of dynamical aggregated computational resources.