CPU
in full
central processing unitPrincipal component of a digital computer, composed of a control unit, an instruction-decoding unit, and an arithmetic-logic unit. The CPU is linked to main memory, peripheral equipment (including input/output devices), and storage units. The control unit integrates computer operations. It selects instructions from the main memory in proper sequence and sends them to the instruction-decoding unit, which interprets them so as to activate functions of the system at appropriate moments. Input data are transferred via the main memory to the arithmetic-logic unit for processing (i.e., addition, subtraction, multiplication, division, and certain logic operations). Larger computers may have two or more CPUs, in which case they are simply called “processors” because each is no longer a “central” unit. See also multiprocessing.
CPU
(Central Processing Unit) The computing part of the computer. Also called the "processor," it is made up of the control unit and ALU. Today, the CPUs of almost all computers are contained on a single chip.
The CPU, clock and main memory make up a computer. A complete computer system requires the addition of control units, input, output and storage devices and an operating system.
From the Mainframe Point of View
Computer professionals involved with mainframes and minicomputers often refer to the whole computer as the CPU, in which case, CPU refers to the processor, memory (RAM) and I/O architecture (channels or buses).
 |
| CPUs Come in Different Sizes |
|---|
| Depending on which end of the field you are in, a CPU can mean the processor, memory and everything inside the cabinet, or just the microprocessor itself. |