Main components of a central processing unit (CPU) (core) are the arithmetic logic unit (ALU ) and the control unit. Usually they contain a plurality of registers and a memory manager (Memory Management Unit (MMU)), which manages the main memory.
One of the central tasks of the processor include the execution of the machine program: the arithmetic and logic operations for processing data from internal or external sources, such as memory.
In addition to these main components that provide the basic functions, there may be other processing units that provide specialized functions and relieve the actual processor – these units are usually referred to as co-processors.
The modern form of the central processing unit (CPU) is the microprocessor, which combines all components of the processor in an integrated circuit (microchip).
Modern processors for desktop, notebook computers, smartphones and tablet computers are often multi-core processors with two, four or more processor cores. The cores are in this case often an independent processors with Steuer-/Leitwerk and arithmetic unit on one chip.
Examples include the Intel Core 2, AMD Athlon X2 or Nvidia Tegra. A clear distinction between the terms processor, main processor, CPU and processor core is not found in the literature.
Processors are often used in the area of embedded systems for the control of household appliances, industrial equipment, consumer electronics, etc.
In mainframes, mostly proprietary processor architectures were used, these include IBM (PowerPC, Cell processor) or SUN (SPARC processor), today mostly customized versions of popular PC processor models are used.
Processors for embedded systems account for about 95% of the processor market, while 90% of them are micro-controllers, which in addition to the actual processor functions also offer special hardware interfaces or directly integrated sensors. Only about 5% are used in personal computers , workstations or servers.
In the 1930s, the arithmetic unit of a computer initially consisted of relays and mechanical components, eg in the Zuse Z3. These first computers were electromechanical computers, these were slow and very prone to failure. Even in the 1940s they began to build computers with the help of electron tubes, such as the ENIAC.
In the 1950s, the unreliable vacuum tubes were replaced by transistors to reduce power consumption of the computer. Initially, the processors were composed of individual transistors. Over the years, but they brought more and more transistor functions under on integrated circuits (ICs ) .
The increasing integration of more and more transistor and gate functions on a chip led drastically reduced use of transistors.