The Central Processing Unit

The microprocessor is the IC, or chip, that forms the core of your computer’s “brain.” It coordinates all the action and does all the calculations. It is located on the motherboard, or main circuit board. This board is sometimes called the logic board. The microprocessor, together with various other circuits, comprises the central processing unit (CPU). Auxiliary circuits can be fabricated onto the same chip as the microprocessor, but they are often separate. The external chips contain memory, storage, and programming instructions.
 
You might think of the microprocessor as the computer’s conscious mind, which directs the behavior of the machine by deliberate control. The CPU, controlled by the microprocessor, represents the PC’s entire mind, conscious and subconscious. All the ancillary circuits, in conjunction with the CPU, make up the nervous system. Peripherals such as printers, disk drives, mice, speech recognition/synthesis apparatus, modems, and displays are the hands, ears, eyes, and mouth of the system. In advanced computer systems there can also be robots, vision systems, various home appliances, surveillance apparatus, medical devices, and other exotic equipment under the control of the CPU.