Microprocessor

n. integrated circuit that performs the central processing and internal functions of a computer (Computers)

A microprocessor is a programmable digital electronic component that incorporates the functions of a central processing unit (CPU) on a single semiconducting integrated circuit (IC). The microprocessor was born by reducing the word size of the CPU from 32 bits to 4 bits, so that the transistors of its logic circuits would fit onto a single part. One or more microprocessors typically serve as the CPU in a computer system, embedded system, or handheld device. Microprocessors made possible the advent of the microcomputer in the mid-1970s. Before this period, electronic CPUs were typically made from bulky discrete switching devices (and later small-scale integrated circuits) containing the equivalent of only a few transistors. By integrating the processor onto one or a very few large-scale integrated circuit packages (containing the equivalent of thousands or millions of discrete transistors), the cost of processor power was greatly reduced. Since the advent of the IC in the mid-1970s, the microprocessor has become the most prevalent implementation of the CPU, nearly completely replacing all other forms. See History of computing hardware for pre-electronic and early electronic computers.
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Noun
1. integrated circuit semiconductor chip that performs the bulk of the processing and controls the parts of a system; "a microprocessor functions as the central processing unit of a microcomputer"; "a disk drive contains a microprocessor to handle the internal functions of the drive"
(hypernym) chip, microchip, micro chip, silicon chip
(part-holonym) personal computer, PC, microcomputer

A central processing unit implemented on a single chip. (188 )

<architecture> (Or "micro") A computer whose entire CPU is contained on one (or a small number of) integrated circuits.
The important characteristics of a microprocessor are the widths of its internal and external address bus and data bus (and instruction), its clock rate and its instruction set. Processors are also often classified as either RISC or CISC.
The first commercial microprocessor was the Intel 4004 which appeared in 1971. This was the CPU member of a set of four LSI integrated circuits called the MCS-4, which was originally designed for use in a calculator but was marketed as "programmable controller for logic replacement". The 4004 is referred to as a 4-bit microprocessor since it processed only 4 bits of data at a time. This very short word size is due mainly to the limitations imposed by the maximum integrated circuit density then achievable.
As integrated circuit densities increased with the rapid development of integrated circuit manufacturing technology, the power and performance of the microprocessors also increased. This is reflected in the increase in the CPU word size to 4, 8, 16, and by mid-1980s, 32 bits. The smaller microprocessors have relatively simple instruction sets, e.g., no floating point instructions, but they are nevertheless suitable as controllers for a very wide range of applications such as car engines and microwave ovens.
The Intel 4004 was followed with, among others the 4040, 8008, 8080, 8086, 80186, 80286, 80386, 486 and Pentium. Other families include the Motorola 6800 and 680x0 families, National Semiconductor NS16000 and NS32000, SPARC, ARM, MIPS, Zilog Z8000, PowerPC and the Inmos Transputer family.
The larger, more recent microprocessors families have gradually acquired most of the features of large computers. As the microprocessor industry has matured, several families of microprocessors have evolved into de facto industrial standards with multiple manufacturers and numerous "support" chips including RAM, ROM, I/O controllers etc.
A single chip microprocessor may include other components such as memory (RAM, ROM, PROM), memory management, caches, floating-point unit, input/output ports and timers. Such devices are also known as microcontrollers.
The one-chip microcomputer is in many respects, a landmark development in computer technology because it reduces the computer to a small, inexpensive, and easily replaceable design component.
Microcomputers have given rise to a new class of general-purpose machines called personal computers. These are small low cost computers that are designed to sit on an ordinary office desk or to be portable and fuelled the computer boom of the late 1980s. The most widespread example is the also IBM PC, based on microprocessors from Intel Corporation. Apple Computers, Inc. have also produced a range of personal computers, as have several other companies.
See also killer micro, minicomputer, CPU Info Center.
(2002-07-16)