Processor (computing)

In computing and computer science, a processor or processing unit is an electrical component (digital circuit) that performs operations on an external data source, usually memory or some other data stream. It typically takes the form of a microprocessor, which can be implemented on a single metal–oxide–semiconductor integrated circuit chip. In the past, processors were constructed using multiple individual vacuum tubes, multiple individual transistors, or multiple integrated circuits. Today, processors use built-in transistors. The term is frequently used to refer to the central processing unit (CPU), the main processor in a system. However, it can also refer to other coprocessors, such as a graphics processing unit (GPU). Traditional processors are typically based on silicon; however, researchers have developed experimental processors based on alternative materials such as carbon nanotubes, graphene, diamond, and alloys made of elements from groups three and five of the periodic table. Transistors made of a single sheet of silicon atoms one atom tall and other 2D materials have been researched for use in processors. Quantum processors have been created; they use quantum superposition to represent bits (called qubits) instead of only an on or off state. Moore's law, named after Gordon Moore, is the observation and projection via historical trend that the number of transistors in integrated circuits, and therefore processors by extension, doubles every two years. The progress of processors has followed Moore's law closely. Central processing units (CPUs) are the primary processors in most computers. They are designed to handle a wide variety of general computing tasks rather than only a few domain-specific tasks. If based on the von Neumann architecture, they contain at least a control unit (CU), an arithmetic logic unit (ALU), and processor registers. In practice, CPUs in personal computers are usually also connected, through the motherboard, to a main memory bank, hard drive or other permanent storage, and peripherals, such as a keyboard and mouse.