Copyright © 2007 Dorling Kindersley
A microchip is an electronic device built as a single unit from many miniature components—mainly transistors. It is plugged in to a socket on a printed circuit board to connect it to other components.
Each kind of microchip performs a different task, and is identified by a code number. Some microchips work with analog signals (a microchip with code 741 is an analog amplifier). Others work with digital signals—to act as LOGIC GATES, or to get digital sound from a CD.
Microchips are made by building up electronic circuits in a tiny wafer (slice) or pure silicon in a complicated layer-by-layer process. The different circuit components are produced by doping (treating) areas of the silicon with different chemicals.
Digital microchips send and receive digital electronic signals in binary code. All information is represented by on/off signals. These signals are processed by the transistors on microchips. When a switch is on, it is the digit 1; when it is off, it is the digit 0. The binary code for the letter “a” on a keyboard is 01100001.
A logic gate is a digital circuit that makes a simple decision. Logic gates include AND, OR, NOT, NOR, and NAND gates. Logic gate circuits can be made with individual transistors, or formed on microchips.