资料来源 : pyDict

微处理器

资料来源 : WordNet®

microprocessor
     n : 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"

资料来源 : Free On-Line Dictionary of Computing

microprocessor
     
         (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 computer}s.  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)