The choice of the microprocessor is very important in selecting any microcomputer system because of the related compatibility and performance issues. Microprocessors for personal computer systems are manufactured by only a few companies. It best known is Intel, whose newest line of processors are called Pentium II. The fastest among these Pentium II chips are the 400MHz Xeon processors. Other companies produce "clone" microprocessors which uses the same Intel CICS instruction set and therefore can run the same software. Less expensive computers also use these chips, which are quite reliable and perform well in comparison to those produced by Intel. There are two major chip makers producing Intel-style "clone" microprocessors: Cyrix, a wholly owned subsidiary of National Semiconductor and Advanced Micro Devices, Inc. [AMD].
             Another well-known chip manufacturer is Motorola, which made the original "family" of M68000 microprocessors for Apple Macintosh computer. A third very important microprocessor maker is IBM. IBM and Motorola have cooperated in producing a very advanced microprocessor called the PowerPC. The PowerPC is based upon RISC architecture and used in the newest Apple Macintosh computers. The PowerPC chip is also used in mid-range computing systems such as IBM's AS/400 line of computers which are extensively used in businesses today. In 1998 IBM announced a major breakthrough in processor manufacturing that permits the use of copper wires, rather than the traditional aluminum interconnection, to link transistors in chips. Copper has less electrical resistance than aluminum, and transmits electrical signals faster; less resistance also permits cooler running temperatures. IBM is able to produce extremely intricate circuit designs with copper at widths of 0.20 microns. which is about 20% !
             smaller than current technology. A micron is 1 millionth of a meter; one-fourth of a micron is hundreds of times thinner...