Introduction to Microprocessors

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Introduction to Microprocessors

• From Wikipedia, the free encyclopedia

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Microprocessor

• A microprocessor incorporates most or all of the
  functions of a central processing unit (CPU) on a
  single integrated circuit (IC). 1
• The first microprocessors emerged in the early
  1970s and were used for electronic calculators,
  using BCD arithmetics on 4-bit words.
• Other embedded uses of 4 and 8-bit
  microprocessors, such as terminals, printers,
  various kinds of automation etc, followed rather
  quickly.
• Affordable 8-bit microprocessors with 16-bit
  addressing also led to the first general purpose
  microcomputers in the mid-1970s.

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Microprocessor

• Die of an Intel 80486DX2 microprocessor (actual
  size 126.75 mm) in its packaging

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Central processing unit

• A central processing unit (CPU), or sometimes
  just called processor, is a description of a
  class of logic machines that can execute computer
  programs.
• This broad definition can easily be applied to
  many early computers that existed long before the
  term "CPU" ever came into widespread usage.
  However, the term itself and its initialism have
  been in use in the computer industry at least
  since the early 1960s (Weik 1961).
• The form, design and implementation of CPUs have
  changed dramatically since the earliest examples,
  but their fundamental operation has remained much
  the same.

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Central processing unit

• Early CPUs were custom-designed as a part of a
  larger, usually one-of-a-kind, computer. However,
  this costly method of designing custom CPUs for a
  particular application has largely given way to
  the development of mass-produced processors that
  are suited for one or many purposes.
• This standardization trend generally began in the
  era of discrete transistor mainframes and
  minicomputers and has rapidly accelerated with
  the popularization of the integrated circuit
  (IC).
• The IC has allowed increasingly complex CPUs to
  be designed and manufactured in very small spaces
  (on the order of millimeters). Both the
  miniaturization and standardization of CPUs have
  increased the presence of these digital devices
  in modern life far beyond the limited application
  of dedicated computing machines. Modern
  microprocessors appear in everything from
  automobiles to cell phones to children's toys.

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Central processing unit

• Prior to the advent of machines that resemble
  today's CPUs, computers such as the ENIAC had to
  be physically rewired in order to perform
  different tasks.
• These machines are often referred to as
  "fixed-program computers," since they had to be
  physically reconfigured in order to run a
  different program.
• Since the term "CPU" is generally defined as a
  software (computer program) execution device, the
  earliest devices that could rightly be called
  CPUs came with the advent of the stored-program
  computer.

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... like being inside the computer
slartmagazine.com
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EDVAC, one of the first electronic stored
program computers.
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ENIAC

• The idea of a stored-program computer was already
  present during ENIAC's design, but was initially
  omitted so the machine could be finished sooner.
  On June 30, 1945, before ENIAC was even
  completed, mathematician John von Neumann
  distributed the paper entitled "First Draft of a
  Report on the EDVAC."
• It outlined the design of a stored-program
  computer that would eventually be completed in
  August 1949 (von Neumann 1945). EDVAC was
  designed to perform a certain number of
  instructions (or operations) of various types.
  These instructions could be combined to create
  useful programs for the EDVAC to run.
• Significantly, the programs written for EDVAC
  were stored in high-speed computer memory rather
  than specified by the physical wiring of the
  computer. This overcame a severe limitation of
  ENIAC, which was the large amount of time and
  effort it took to reconfigure the computer to
  perform a new task.
• With von Neumann's design, the program, or
  software, that EDVAC ran could be changed simply
  by changing the contents of the computer's
  memory.1

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ENIAC

• ENIAC, short for Electronic Numerical Integrator
  And Computer,1 was the first general-purpose
  electronic computer. Precisely, it was the first
  high-speed, purely electronic, Turing-complete,
  digital computer capable of being reprogrammed to
  solve a full range of computing problems,2
  since earlier machines had been built with some
  of these properties. ENIAC was designed and built
  to calculate artillery firing tables for the U.S.
  Army's Ballistic Research Laboratory.
• The contract was signed on June 5, 1943 and
  Project PX was constructed by the University of
  Pennsylvania's Moore School of Electrical
  Engineering from July, 1943. It was unveiled on
  February 14, 1946 at Penn, having cost almost
  500,000. ENIAC was shut down on November 9, 1946
  for a refurbishment and a memory upgrade, and was
  transferred to Aberdeen Proving Ground, Maryland
  in 1947. There, on July 29 of that year, it was
  turned on and would be in continuous operation
  until 1145 p.m. on October 2, 1955.

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Glen Beck (background) and Betty Snyder
(foreground) program the ENIAC in BRL building
328. (U.S. Army photo)
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Programmers Betty Jean Jennings (left) and Fran
Bilas (right) operate the ENIAC's main control
panel at the Moore School of Electrical
Engineering. (U.S. Army photo from the archives
of the ARL Technical Library)
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Cpl. Irwin Goldstein (foreground) sets the
switches on one of the ENIAC's function tables at
the Moore School of Electrical Engineering. (U.S.
Army photo)
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Microprocessor

• Processors were for a long period constructed out
  of small and medium-scale ICs containing the
  equivalent of a few to a few hundred transistors.
• The integration of the whole CPU onto a single
  VLSI chip therefore greatly reduced the cost of
  processing capacity.
• From their humble beginnings, continued increases
  in microprocessor capacity has rendered other
  forms of computers almost completely obsolete
  (see history of computing hardware), with one or
  more microprocessor as processing element in
  everything from the smallest embedded systems and
  handheld devices to the largest mainframes and
  super computers.

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Microprocessor

• Three projects arguably delivered a complete
  microprocessor at about the same time, namely
  Intel's 4004, the Texas Instruments (TI) TMS
  1000, and Garrett AiResearch's Central Air Data
  Computer (CADC).

The 4004 with cover removed (left) and as
actually used (right).
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ARCHITECTURES

• 8-bit designs
• 16-bit designs
• 32-bit designs
• 64-bit designs in personal computers
• Multicore designs
• RISC
• Special-purpose designs
• microcontrollers, digital signal processors (DSP)
  and graphics processing units (GPU).

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• 65xx
• MOS Technology 6502
• Western Design Center 65xx
• ARM family
• Altera Nios, Nios II
• Atmel AVR architecture (purely microcontrollers)
• EISC
• RCA 1802 (aka RCA COSMAC, CDP1802)
• DEC Alpha
• Intel
• 4004, 4040
• 8080, 8085
• 8048, 8051
• iAPX 432
• i860, i960
• Itanium
• LatticeMico32
• M32R architecture
• MIPS architecture

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• NSC 320xx
• OpenCores OpenRISC architecture
• PA-RISC family
• National Semiconductor SC/MP ("scamp")
• Signetics 2650
• SPARC
• SuperH family
• Transmeta Crusoe, Efficeon (VLIW architectures,
  IA-32 32-bit Intel x86 emulator)
• INMOS Transputer
• x86 architecture
• Intel 8086, 8088, 80186, 80188 (16-bit real
  mode-only x86 architecture)
• Intel 80286 (16-bit real mode and protected mode
  x86 architecture)
• IA-32 32-bit x86 architecture
• x86-64 64-bit x86 architecture
• XAP processor from Cambridge Consultants
• Xilinx
• MicroBlaze soft processor
• PowerPC405 embedded hard processor in Virtex
  FPGAs
• Zilog