s, and the system became much less expensive to build. a) Integrated Circuits Late in the 1960s the integrated circuit, or IC, was introduced, making it possible for many transistors to be fabricated on one silicon substrate, with inter- connecting wires plated in place. The IC resulted in a further reduction in price, size, and failure rate. The microprocessor became a reality in the mid-1970s with the introduction of the large scale integrated (LSI) circuit and, later, the very large scale integrated (VLSI) circuit, with many thousands of interconnected transistors etched into a single silicon substrate. To return, then, to the "switch-checking" capabilities of a modern computer: computers in the 1970s generally were able to check eight switches at a time. That is, they could check eight binary digits, or bits, of data, at every cycle. A group of eight bits is called a byte, each byte containing 256 possible patterns of ONs and OFFs (or 1's and 0's). Each pattern is the equivalent of an instruction, a part of an instruction, or a particular type of datum, such as a number or a character or a graphics symbol. The pattern 11010010, for example, might be binary data-in this case, the decimal number 210 (see NUMBER SYSTEMS)-or it might tell the computer to compare data stored in its switches to data stored in a certain memory-chip location. The development of processors that can handle 16, 32, and 64 bits of data at a time has increased the speed of computers. The complete collection of recognizable patterns-the total list of operations-of which a computer is capable is called its instruction set. Both factors-number of bits at a time, and size of instruction sets-continue to increase with the ongoing development of modern digital computers. IV. COMPUTERS OF THE 90'S a) Computer Networks Major changes in the use of computers have developed since it was first invented. Computers have expanded, via telephone lines, into vast nation-wide, or...
