The CPU
through history
What is the CPU?
The 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 operations specified by the instructions. The term has been used in the computer industry at least since the early 1960s.
Most modern CPUs are microprocessors, meaning they are contained on a single IC chip. Some computers have two or more CPUs on a single chip and thus are capable of multiprocessing; these are called multi-core processors. An IC that contains a CPU may also contain memory, peripheral devices, and other components of a computer.
Through History
The form, design, and implementation of CPUs have changed over the course of their history, but their fundamental operation remains much the same. Principal components of a CPU include the ALU, which performs arithmetic and logical operations, and the CU, which fetches instructions from the memory, decodes and executes them, calling on the services of the ALU when necessary.