Processors and memory have improved at an incredible rate, because computer designers have long embraced the latest in electronic technology to try to win the race to design a better computer. A transistor is simply an on/off switch controlled by electricity. Th e integrated circuit (IC) combined dozens to hundreds of transistors into a single chip. When Gordon Moore predicted the continuous doubling of resources, he was predicting the growth rate of the number of transistors per chip.
To describe the tremendous increase in the number of transistors from hundreds to millions, the adjective very large scale is added to the term, creating the abbreviation VLSI, for very large-scale integrated circuit. Th is rate of increasing integration has been remarkably stable. The manufacture of a chip begins with silicon, a substance found in sand. Because silicon does not conduct electricity well, it is called a semiconductor. With a special chemical process, it is possible to add materials to silicon that allow tiny areas to transform into one of three devices:
· Excellent conductors of electricity (using either microscopic copper or
· Excellent insulators from electricity (like plastic sheathing or glass)
· Areas that can conduct or insulate under special conditions (as a switch)
Transistors fall in the last category. A VLSI circuit, then, is just billions of combinations of conductors, insulators, and switches manufactured in a single small package.