Components

Holistic purpose computer has four main components: the arithmetic logic unit (ALU), the control unit , the memory , and the input and output devices (collectively termed I/O). These parts are interconnected by buses , often made of groups of wires .
Inside each of these parts are thousands to trillions of small electrical circuits and this can be turned off or on by means of an electronic switch . Each circuit represents a bit (binary digit) of information so that when the circuit is on it represents a "1", and when off it represents a "0" (in positive logic representation). The circuits are arranged in logic gates so that several of the circuits may control the state of one or more of the other circuits.