Winn L. Rosch Hardware Bible, Sixth Edition

Background

Every modern microprocessor starts with the basics—clocked-logic digital circuitry. The chip has millions of separate gates combined into three basic function blocks: the input/output unit (or I/O unit), the control unit, and the arithmetic/logic unit (ALU). The last two are sometimes jointly called the central processingunit (CPU), although the same term often is used as a synonym for the entire microprocessor. Some chipmakers further subdivide these units, give them other names, or include more than one of each in a particular microprocessor. In any case, the functions of these three units are an inherent part of any chip. The differences are mostly a matter of nomenclature, because you can understand the entire operation of any ...