Microprocessor_pp1a_ppt.ppt

Chapter 1: Introduction to the
Microprocessor and Computer

Copyright ©2009 by Pearson Education, Inc.
Upper Saddle River, New Jersey 07458 • All rights reserved.
The Intel Microprocessors: 8086/8088, 80186/80188, 80286, 80386, 80486 Pentium,
Pentium Pro Processor, Pentium II, Pentium, 4, and Core2 with 64-bit Extensions
Architecture, Programming, and Interfacing, Eighth Edition
Barry B. Brey
Introduction
• Overview of Intel microprocessors.
• Discussion of history of computers.
• Function of the microprocessor.
• Terms and jargon (computerese).

Barry B. Brey
Chapter Objectives
• Converse by using appropriate computer
terminology such as bit, byte, data, real
memory system, protected mode memory
system, Windows, DOS, I/O.
• Detail history of the computer and list
applications performed by computer systems.
• Provide an overview of the various 80X86 and
Pentium family members.
Upon completion of this chapter, you will be able to:

Barry B. Brey
Chapter Objectives
• Draw the block diagram of a computer system
and explain the purpose of each block.
• Describe the function of the microprocessor
and detail its basic operation.
• Define the contents of the memory system in
the personal computer.
(cont.)

Barry B. Brey
Chapter Objectives
• Convert between binary, decimal, and
hexadecimal numbers.
• Differentiate and represent numeric and
alphabetic information as integers, floating-
point, BCD, and ASCII data.
(cont.)

Barry B. Brey
1–1 A HISTORICAL BACKGROUND
• Events leading to development of
the microprocessor.
• 80X86, Pentium, Pentium Pro, Pentium III,
Pentium 4, and Core2 microprocessors.
• While not essential to understand the
microprocessor, furnishes:
– interesting reading
– historical perspective of fast-paced evolution

Barry B. Brey
The Mechanical Age
• Idea of computing system not new.
• Calculating with a machine dates to 500 BC.
• Babylonians invented the abacus.
– first mechanical calculator
– strings of beads perform calculations
• Used by ancient priests to keep track of
storehouses of grain.
– still in use today

Barry B. Brey
• In 1642 mathematician Blaise Pascal invented
a calculator constructed of gears and wheels.
– each gear contained 10 teeth
• When moved one complete revolution, a
second gear advances one place.
– same principle used in automobile odometer
• Basis of all mechanical calculators.
• PASCAL programming language is named in
honor of Blaise Pascal.

Barry B. Brey
• First practical geared mechanical machines
to compute information date to early 1800s.
– humans dreamed of mechanical machines that
could compute with a program
• One early pioneer of mechanical computing
machinery was Charles Babbage.
– aided by Ada Byron, Countess of Lovelace
• Commissioned in 1823 by Royal Astronomical
Society to build programmable calculating
machine.
– to generate Royal Navy navigational tables

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• He began to create his Analytical Engine.
• Steam-powered mechanical computer.
– stored a thousand 20-digit decimal numbers
• Variable program could modify function of the
machine to perform various calculating tasks.
– input through punched cards, much as computers
in the 1950s and 1960s used punched cards
• It is assumed idea of punched cards is from
Joseph Jacquard, a Frenchman.
– used punched cards as input to a weaving
machine he invented in 1801

Barry B. Brey
• Jacquard’s loom used punched cards to select
intricate weaving patterns in cloth it produced.
– punched cards programmed the loom
• After many years of work Babbage’s dream
began to fade.
– machinists of his day unable to create the parts
needed to complete his work
• Analytical Engine required more than 50,000
machined parts.
– they could not be made with enough precision to
allow his engine to function reliably

Barry B. Brey
The Electrical Age
• 1800s saw advent of the electric motor.
– conceived by Michael Faraday
• Also a multitude of electrically motor-driven
adding machines based on the Pascal
mechanical calculator.
– common office equipment until 1970s
• Introduced by Bomar Corporation the Bomar
Brain, was a handheld electronic calculator.
– first appeared in early 1970s

Barry B. Brey
• Monroe also pioneer of electronic calculators,
making desktop models.
– four-function; size of cash registers
• In 1889, Herman Hollerith developed the
punched card for storing data.
– apparently also borrowed Jacquard ideas
• Also developed mechanical machine that
counted, sorted, and collated information
stored on punched cards.
– driven by one of the new electric motors

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• Calculating by machine intrigued US govt.
– Hollerith commissioned to use system to store
and tabulate 1890 census information
• In 1896 Hollerith formed Tabulating Machine
Company.
– developed line of machines using punched cards
for tabulation
• After a number of mergers, Tabulating
Machine Co. was formed into International
Business Machines Corporation.
– referred to more commonly as IBM, Inc.

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• Punched cards used in early computer
systems often called Hollerith cards.
– in honor of Herman Hollerith
• 12-bit code used on a punched card is called
the Hollerith code.

Barry B. Brey
• Mechanical-electric machines dominated
information processing world until 1941.
– construction of first electronic calculating machine
• German inventor Konrad Zuse, invented the
first modern electromechanical computer.
• His Z3 calculating computer probably
invented for aircraft and missile design.
– during World War II for the German war effort
• Z3 a relay logic machine clocked at 5.33 Hz.
– far slower than latest multiple GHz
microprocessors

Barry B. Brey
Figure 1–1 The Z3 computer developed by Konrad Zuse uses a 5.33 hertz clocking
frequency. (Photo courtesy of Horst Zuse, the son of Konrad.)

Barry B. Brey
• Had Zuse been given adequate funding,
likely would have developed a much more
powerful computer system.
• In 1936 Zuse constructed a mechanical
version of his system.
• In 1939 constructed first electromechanical
computer system, called the Z2.
– Zuse today receiving belated honors for
pioneering work in the area of digital electronics

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• First electronic computer placed in operation
to break secret German military codes.
• recently discovered through declassification of
military documents of 1943.
• System invented by Alan Turing.
– used vacuum tubes,
• Turing called his machine Colossus.
– probably because of its size

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• Although design allowed it to break secret
German military codes generated by the
mechanical Enigma machine, it could not
solve other problems.
• Colossus not programmable
• A fixed-program computer system
– today often called a special-purpose computer
• First general-purpose, programmable
electronic computer system developed 1946.
– at University of Pennsylvania

Barry B. Brey
• Electronic Numerical Integrator and
Calculator (ENIAC), a huge machine.
– over 17,000 vacuum tubes; 500 miles of wires
– weighed over 30 tons
– about 100,000 operations per second
• Programmed by rewiring its circuits.
– process took many workers several days
– workers changed electrical connections on plug-
boards like early telephone switchboards
• Required frequent maintenance.
– vacuum tube service life a problem

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• December 23, 1947, John Bardeen, William
Shockley, and Walter Brattain develop the
transistor at Bell Labs.
• Followed by 1958 invention of the integrated
circuit (IC) by Jack Kilby of Texas Instruments.
• IC led to development of digital integrated
circuits in the 1960s.
– RTL, or resistor-to-transistor logic
• First microprocessor developed at Intel
Corporation in 1971.

Barry B. Brey
• Intel engineers Federico Faggin, Ted Hoff,
and Stan Mazor developed the 4004
microprocessor.
• U.S. Patent 3,821,715.
• Device started the microprocessor revolution
continued today at an ever-accelerating pace.

Barry B. Brey
Programming Advancements
• Once programmable machines developed,
programs and programming languages began
to appear.
• As early practice of rewiring circuits proved
too cumbersome, computer languages began
to appear in order to control the computer.
• The first, machine language, was constructed
of ones and zeros using binary codes.
– stored in the computer memory system as groups
of instructions called a program

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• More efficient than rewiring a machine to
program it.
– still time-consuming to develop a program due
to sheer number of program codes required
• Mathematician John von Neumann first
modern person to develop a system to accept
instructions and store them in memory.
• Computers are often called von Neumann
machines in his honor.
– recall that Babbage also had developed the
concept long before von Neumann

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• Once systems such as UNIVAC became
available in early 1950s, assembly language
was used to simplify entering binary code.
• Assembler allows programmer to use
mnemonic codes…
– such as ADD for addition
• In place of a binary number.
– such as 0100 0111
• Assembly language an aid to programming.

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• 1957 Grace Hopper developed first high-level
programming language called FLOWMATIC.
– computers became easier to program
• In same year, IBM developed FORTRAN
FORmula TRANslator) for its systems.
– Allowed programmers to develop programs that
used formulas to solve mathematical problems.
• FORTRAN is still used by some scientists for
computer programming.
– Similar language, ALGOL (ALGOrithmic
Language) introduced about a year later

Barry B. Brey
• First successful, widespread programming
language for business applications was
COBOL (COmputer Business Oriented
Language).
• COBOL usage diminished in recent years.
– still a player in some large business and
government systems
• Another once-popular business language is
RPG (Report Program Generator).
– allows programming by specifying form of the
input, output, and calculations

Barry B. Brey
• Since early days of programming, additional
languages have appeared.
• Some common modern programming
languages are BASIC, C#, C/C++, Java,
PASCAL, and ADA.
– BASIC and PASCAL languages both designed as
teaching languages, but escaped the classroom.
• BASIC used in many computer systems.
– among most common languages today
– probably easiest of all to learn

Barry B. Brey
• Estimates indicate BASIC used for 80% of
programs written by personal computer users.
• Visual BASIC, has made programming in the
Windows environment easier.
– could supplant C/C++ and PASCAL
as a scientific language, but is doubtful
• C# language is gaining headway.
– may actually replace C/C++ and most other
languages including Java
– may eventually replace BASIC
• Which becomes dominant remains in future.

Barry B. Brey
• Scientific community uses primarily C/C++.
– occasionally PASCAL and FORTRAN
• Recent survey of embedded system
developers showed C was used by 60%.
– 30% used assembly language
– remainder used BASIC and JAVA
• These languages allow programmer almost
complete control over the programming
environment and computer system.
– especially C/C++

Barry B. Brey
• C/C++ replacing some low-level machine
control software or drivers normally reserved
for assembly language.
• Assembly language still plays important role.
– many video games written almost exclusively
in assembly language
• Assembly also interspersed with C/C++ to
perform machine control functions efficiently.
– some newer parallel instructions found on
Pentium and Core2 microprocessors only
programmable in assembly language

Barry B. Brey
• ADA used heavily by Department of Defense.
• The ADA language was named in honor of
Augusta Ada Byron, Countess of Lovelace.
• The Countess worked with Charles Babbage
in the early 1800s.
– development of software for Analytical Engine

Barry B. Brey
The Microprocessor Age
• World’s first microprocessor the Intel 4004.
• A 4-bit microprocessor-programmable
controller on a chip.
• Addressed 4096, 4-bit-wide memory locations.
– a bit is a binary digit with a value of one or zero
– 4-bit-wide memory location often called a nibble
• The 4004 instruction set contained 45
instructions.

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• Fabricated with then-current state-of-the-art
P-channel MOSFET technology.
• Executed instructions at 50 KIPs (kilo-
instructions per second).
– slow compared to 100,000 instructions per
second by 30-ton ENIAC computer in 1946
• Difference was that 4004 weighed less than
an ounce.
• 4-bit microprocessor debuted in early game
systems and small control systems.
– early shuffleboard game produced by Bailey

Barry B. Brey
• Main problems with early microprocessor
were speed, word width, and memory size.
• Evolution of 4-bit microprocessor ended when
Intel released the 4040, an updated 4004.
– operated at a higher speed; lacked improvements
in word width and memory size
• Texas Instruments and others also produced
4-bit microprocessors.
– still survives in low-end applications such as
microwave ovens and small control systems
– Calculators still based on 4-bit BCD (binary-
coded decimal) codes

Barry B. Brey
• With the microprocessor a commercially viable
product, Intel released 8008 in 1971.
– extended 8-bit version of 4004 microprocessor
• Addressed expanded memory of 16K bytes.
– A byte is generally an 8-bit-wide binary number
and a K is 1024.
– memory size often specified in K bytes
• Contained additional instructions, 48 total.
• Provided opportunity for application in more
advanced systems.
– engineers developed demanding uses for 8008

Barry B. Brey
• Somewhat small memory size, slow speed,
and instruction set limited 8008 usefulness.
• Intel introduced 8080 microprocessor in 1973.
– first of the modem 8-bit microprocessors
• Motorola Corporation introduced MC6800
microprocessor about six months later.
• 8080—and, to a lesser degree, the MC6800—
ushered in the age of the microprocessor.
– other companies soon introduced their own
versions of the 8-bit microprocessor

Barry B. Brey
Table 1–1 Early 8-bit microprocessors

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• Only Intel and Motorola continue to create
new, improved microprocessors.
– IBM also produces Motorola-style
microprocessors
• Motorola sold its microprocessor division.
– now called Freescale Semiconductors, Inc.
• Zilog still manufactures microprocessors.
– microcontrollers and embedded controllers
instead of general-purpose microprocessors

Barry B. Brey
What Was Special about the 8080?
• 8080 addressed four times more memory.
– 64K bytes vs l6K bytes for 8008
• Executed additional instructions; 10x faster.
– addition taking 20 µs on an 8008-based system
required only 2.0 µs on an 8080-based system
• TTL (transistor-transistor logic) compatible.
– the 8008 was not directly compatible
• Interfacing made easier and less expensive.

Barry B. Brey
• The MITS Altair 8800, was released in 1974.
– number 8800 probably chosen to avoid copyright
violations with Intel
• BASIC language interpreter for the Altair 8800
computer developed in 1975.
– Bill Gates and Paul Allen, founders of Microsoft
Corporation
• The assembler program for the Altair 8800
was written by Digital Research Corporation.
– once produced DR-DOS for the personal
computer

Barry B. Brey
The 8085 Microprocessor
• In 1977 Intel Corporation introduced an
updated version of the 8080—the 8085.
• Last 8-bit, general-purpose microprocessor
developed by Intel.
• Slightly more advanced than 8080; executed
software at an even higher speed.
– 769,230 instructions per second vs 500,000 per
second on the 8080).

Barry B. Brey
• Main advantages of 8085 were its internal
clock generator and system controller, and
higher clock frequency.
– higher level of component integration reduced
the 8085’s cost and increased its usefulness
• Intel has sold over 100 million of the 8085.
– its most successful 8-bit, general-purpose
microprocessor.
– also manufactured by many other companies,
meaning over 200 million in existence
• Applications that contain the 8085 will likely
continue to be popular.

Barry B. Brey
• Zilog Corporation sold 500 million of their
8-bit Z80microprocessors.
• The Z-80 is machine language–compatible
with the 8085.
• Over 700 million microprocessors execute
8085/Z-80 compatible code.

Barry B. Brey
The Modern Microprocessor
• In 1978 Intel released the 8086; a year or so
later, it released the 8088.
• Both devices are 16-bit microprocessors.
– executed instructions in as little as 400 ns (2.5
millions of instructions per second)
– major improvement over execution speed of 8085
• 8086 & 8088 addressed 1M byte of memory.
– 16 times more memory than the 8085
– 1M-byte memory contains 1024K byte-sized
memory locations or 1,048,576 bytes

Barry B. Brey
• Higher speed and larger memory size allowed
8086 & 8088 to replace smaller
minicomputers in many applications.
• Another feature was a 4- or 6-byte instruction
cache or queue that prefetched instructions
before they were executed.
– queue sped operation of many sequences of
instruction
– basis for the much larger instruction caches
found in modem microprocessors.

Barry B. Brey
• Increased memory size and additional
instructions in 8086/8088 led to many
sophisticated applications.
• Improvements to the instruction set included
multiply and divide instructions.
– missing on earlier microprocessors
• Number of instructions increased.
– from 45 on the 4004, to 246 on the 8085
– over 20,000 variations on the 8086 & 8088

Barry B. Brey
• These microprocessors are called CISC
(complex instruction set computers).
– additional instructions eased task of developing
efficient and sophisticated applications
• 16-bit microprocessor also provided more
internal register storage space.
– additional registers allowed software to be
written more efficiently
– evolved to meet need for larger memory systems

Barry B. Brey
• Popularity of Intel ensured in 1981 when IBM
chose the 8088 in its personal computer.
• Spreadsheets, word processors, spelling
checkers, and computer-based thesauruses
were memory-intensive .
– required more than 64K bytes of memory found
in 8-bit microprocessors to execute efficiently
– The 16-bit 8086 and 8088 provided 1M byte of
memory for these applications

Barry B. Brey
• Even the 1M-byte memory system proved
limiting for databases and other applications.
– Intel introduced the 80286 in 1983
– an updated 8086
• Almost identical to the 8086/8088.
– addressed 16M-byte memory system instead
of a 1M-byte system
• Instruction set almost identical except for a
few additional instructions.
– managed the extra 15M bytes of memory

Barry B. Brey
• 80286 clock speed increased in 8.0 Mhz
version.
– executed some instructions in as little as 250 ns
(4.0 MIPs)
• Some changes to internal execution of
instructions led to eightfold increase in speed
for many instructions.

Barry B. Brey
The 32-Bit Microprocessor
• Applications demanded faster microprocessor
speeds, more memory, and wider data paths.
• Led to the 80386 in 1986 by Intel.
– major overhaul of 16-bit 8086–80286 architecture
• Intel’s first practical microprocessor to contain
a 32-bit data bus and 32-bit memory address.
– Intel produced an earlier, unsuccessful 32-bit
microprocessor called iapx-432

Barry B. Brey
• Through 32-bit buses, 80386 addressed up
to 4G bytes of memory.
– 1G memory = 1024M, or 1,073,741,824 locations
– 1,000,000 typewritten, double-spaced pages of
ASCII text data
• 80386SX addressed 16M bytes of memory
through a 16-bit data and 24-bit address bus.
• 80386SL/80386SLC addressed 32M bytes
memory via 16-bit data, 25-bit address bus.
• 80386SLC contained an internal cache to
process data at even higher rates.

Barry B. Brey
• Intel released 80386EX in 1995.
• Called an embedded PC.
– contains all components of the AT class
computer on a single integrated circuit
• 24 lines for input/output data.
• 26-bit address bus; 16-bit data bus.
• DRAM refresh controller.
• Programmable chip selection logic

Barry B. Brey
• Applications needing higher speeds and large
memory systems include software systems
that use a GUI, or graphical user interface
• Modern graphical displays contain 256,000
or more picture elements (pixels, or pels).
• VGA (variable graphics array) resolution is
640 pixels per scanning line by 480 lines.
– resolution used to display computer boot screen
• To display one screen of information, each
picture element must be changed.
– requires a high-speed microprocessor

Barry B. Brey
• GUI packages require high microprocessor
speeds and accelerated video adapters for
quick and efficient manipulation of video text
and graphical data.
– the most striking system is Microsoft Windows
• GUI often called a WYSIWYG (what you see
is what you get) display.

Barry B. Brey
• 32-bit microprocessor needed due to size of
its data bus.
– transfers real (single-precision floating-point)
numbers that require 32-bit-wide memory
• To process 32-bit real numbers, the
microprocessor must efficiently pass them
between itself and memory.
– with 8-bit data bus, takes four read or write cycles
– only one read or write cycle is required for 32 bit
• Significantly increases speed of any program
that manipulates real numbers.

Barry B. Brey
• High-level languages, spreadsheets, and
database management systems use real
numbers for data storage.
– also used in graphical design packages that use
vectors to plot images on the video screen
– CAD (computer-aided drafting/design)
systems as AUTOCAD, ORCAD
• 80386 had higher clocking speeds and
included a memory management unit.
– allowed memory resources to be allocated
and managed by the operating system

Barry B. Brey
• 80386 included hardware circuitry for memory
management and assignment.
– improved efficiency, reduced software overhead
– earlier microprocessors left memory
management completely to the software
• Instruction set, memory management upward-
compatible with 8086, 8088, and 80286.
– additional instructions referenced 32-bit registers
and managed the memory system
• Features allowed older, 16-bit software to
operate on the 80386 microprocessor.

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• In 1989 Intel released the 8048.
• Highly integrated package.
• 80386-like microprocessor.
• 80387-like numeric coprocessor.
• 8K-byte cache memory system.

Barry B. Brey
• Internal structure of 80486 modified so about
half of its instructions executed in one clock
instead of two clocks.
– in a 50 MHz version, about half of instructions
executed in 25 ns (50 MIPs)
– 50% over 80386 operated at same clock speed
• Double-clocked 80486DX2 executed
instructions at 66 MHz, with memory transfers
at 33 MHz.
– called a double-clocked microprocessor

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• A triple-clocked version improved speed to
100 MHz with memory transfers at 33 MHz.
– about the same speed as 60 MHz Pentium.
• Expanded 16K-byte cache.
– in place of standard 8K-byte cache
• Advanced Micro Devices (AMD) produced a
triple-clocked version with a bus speed of 40
MHz and a clock speed of 120 MHz.
• The future promises rates 10 GHz or higher.

Barry B. Brey
• Other versions called OverDrive processors.
– a double-clocked 80486DX that replaced an
80486SX or slower-speed 80486DX
– functioned as a doubled-clocked version of the
microprocessor

Barry B. Brey
The Pentium Microprocessor
• Introduced 1993, Pentium was similar to
80386 and 80486 microprocessors.
• Originally labeled the P5 or 80586.
– Intel decided not to use a number because it
appeared to be impossible to copyright a number
• Introductory versions operated with a clocking
frequency of 60 MHz & 66 MHz, and a speed
of 110 MIPs.

Barry B. Brey
• Double-clocked Pentium at 120 MHz and 133
MHz, also available.
– fastest version produced 233 MHz Pentium
a three and one-half clocked version
• Cache size was increased to 16K bytes from
the 8K cache found in 80486.
• 8K-byte instruction cache and data cache.
• Memory system up to 4G bytes.
• Data bus width increased to a full 64 bits.
• Data bus transfer speed 60 MHz or 66 MHz.
– depending on the version of the Pentium

Barry B. Brey
• Wider data bus width accommodated double-
precision floating-point numbers used in high-
speed, vector-generated graphical displays.
– should allow virtual reality software and video to
operate at more realistic rates
• Widened data bus and higher speed allow
full-frame video displays at scan rates of 30
Hz or higher.
– comparable to commercial television

Barry B. Brey
• Recent Pentium versions also included
additional instructions.
– multimedia extensions, or MMX instructions
• Intel hoped MMX would be widely used
– few software companies have used
– no high-level language support for instructions
• OverDrive (P24T) for older 80486 systems.
• 63 MHz version upgrades 80486DX2 50 MHz
systems; 83 MHz upgrades 66 MHz systems.
– system performs somewhere between a 66 MHz
Pentium and a 75 MHz Pentium

Barry B. Brey
• Pentium OverDrive represents ideal upgrade
path from the 80486 to the Pentium.
– executes two instructions not dependent on each
other, simultaneously per clocking period
– dual integer processors most ingenious feature
– contains two independent internal integer
processors called superscaler technology
• Jump prediction speeds execution of program
loops; internal floating-point coprocessor
handles floating-point data.
• These portend continued success for Intel.

Barry B. Brey
• Intel may allow Pentium to replace some
RISC (reduced instruction set computer)
machines.
• Some newer RISC processors execute more
than one instruction per clock.
– through superscaler technology
• Motorola, Apple, and IBM produce PowerPC, a
RISC with two integer units and a floating-
point unit.
– boosts Macintosh performance, but slow to
efficiently emulate Intel microprocessors

Barry B. Brey
• Currently 6 million Apple Macintosh systems
• 260 million personal computers based on Intel
microprocessors.
• 1998 reports showed 96% of all PCs shipped
with the Windows operating system.
• Apple computer replaced PowerPC with the
Intel Pentium in most of its computer systems.
– appears that PowerPC could not keep pace with
the Pentium line from Intel

Barry B. Brey
• To compare speeds of microprocessors, Intel
devised the iCOMP- rating index.
– composite of SPEC92, ZD Bench, Power Meter
• The iCOMP1 rating index is used to rate the
speed of all Intel microprocessors through the
Pentium.
• Figure 1–2 shows relative speeds of the
80386DX 25 MHz version through the
Pentium 233 MHz version.

Barry B. Brey
Figure 1–2 The Intel iCOMP-rating index.

Barry B. Brey
• Since release of Pentium Pro and Pentium II,
Intel has switched to the iCOMP2- rating.
– scaled by a factor of 10 from the iCOMP1 index
• Figure 1–3 shows iCOMP2 index listing the
Pentium III at speeds up to 1000 MHz.
• Figure 1–4 shows SYSmark 2002 for the
Pentium III and Pentium 4.
• Intel has not released benchmarks that
compare versions of the microprocessor since
the SYSmark 2002.
– newer available do not compare versions

Barry B. Brey
Figure 1–3 The Intel iCOMP2-rating index.

Barry B. Brey
Figure 1–4 Intel microprocessor performance using SYSmark 2002.

Barry B. Brey
Pentium Pro Processor
• A recent entry, formerly named the P6.
• 21 million transistors, integer units, floating-
point unit, clock frequency 150 and 166 MHz
• Internal 16K level-one (L1) cache.
– 8K data, 8K for instructions
– Pentium Pro contains 256K level-two (L2) cache
• Pentium Pro uses three execution engines, to
execute up to three instructions at a time.
– can conflict and still execute in parallel

Barry B. Brey
• Pentium Pro optimized to efficiently execute
32-bit code.
– often bundled with Windows NT rather than
normal versions of Windows 95
– Intel launched Pentium Pro for server market
• Pentium Pro can address 4G-byte or a 64G-
byte memory system.
– 36-bit address bus if configured for a 64G
memory system

Barry B. Brey
Pentium II and Pentium Xeon
Microprocessors
• Pentium II, released 1997, represents new
direction for Intel.
• Intel has placed Pentium II on a small circuit
board, instead of being an integrated circuit.
– L2 cache on main circuit board of not fast
enough to function properly with Pentium II
• Microprocessor on the Pentium II module
actually Pentium Pro with MMX extensions.

Barry B. Brey
• In 1998 Intel changed Pentium II bus speed.
– newer Pentium II uses a 100 MHz bus speed
• Higher speed memory bus requires 8 ns
SDRAM.
– replaces 10 ns SDRAM with 66 MHz bus speed

Barry B. Brey
• Intel announced Xeon in mid-1998.
– specifically designed for high-end workstation
and server applications
• Xeon available with 32K L1 cache and L2
cache size of 512K, 1M, or 2M bytes.
• Xeon functions with the 440GX chip set.
• Also designed to function with four Xeons in
the same system, similar to Pentium Pro.
• Newer product represents strategy change.
– Intel produces a professional and home/business
version of the Pentium II

Barry B. Brey
Pentium III Microprocessor
• Faster core than Pentium II; still a P6 or
Pentium Pro processor.
• Available in slot 1 version mounted on a
plastic cartridge.
• Also socket 370 version called a flip-chip
which looks like older Pentium package.
• Pentium III available with clock frequencies
up to 1 GHz.

Barry B. Brey
• Slot 1 version contains a 512K cache; flip-chip
version contains 256K cache.
• Flip-chip version runs at clock speed; Slot 1
cache version runs at one-half clock speed.
• Both versions use 100 Mhz memory bus.
– Celeron memory bus clock speed 66 MHz
• Front side bus connection, microprocessor to
memory controller, PCI controller, and AGP
controller, now either 100 or 133 MHz.
– this change has improved performance
– memory still runs at 100 MHz

Barry B. Brey
Pentium 4 and Core2
Microprocessors
• Pentium 4 first made available in late 2000.
– most recent version of Pentium called Core2
– uses Intel P6 architecture
• Pentium 4 available to 3.2 GHz and faster.
– supporting chip sets use RAMBUS or DDR
memory in place of SDRAM technology
• Core2 is available at speeds of up to 3 GHz.
– improvement in internal integration, at present
the 0.045 micron or 45 nm technology

Barry B. Brey
• A likely change is a shift from aluminum to
copper interconnections inside the
microprocessor.
• Copper is a better conductor.
– should allow increased clock frequencies
– especially true now that a method for using
copper has surfaced at IBM
• Another event to look for is a change in the
speed of the front side bus.
– increase beyond current maximum 1033 MHz

Barry B. Brey
Pentium 4 and Core2, 64-bit and
Multiple Core Microprocessors
• Recent modifications to Pentium 4 and Core2
include a 64-bit core and multiple cores.
• 64-bit modification allows address of over 4G
bytes of memory through a 64-bit address.
– 40 address pins in these newer versions allow
up to 1T (terabytes) of memory to be accessed
• Also allows 64-bit integer arithmetic.
– less important than ability to address more
memory

Barry B. Brey
• Biggest advancement is inclusion of multiple
cores.
– each core executes a separate task in a program
• Increases speed of execution if program is
written to take advantage of multiple cores.
– called multithreaded applications
• Intel manufactures dual and quad core
versions; number of cores will likely increase
to eight or even sixteen.

Barry B. Brey
• Multiple cores are current solution to providing
faster microprocessors.
• Intel recently demonstrated Core2 containing
80 cores, using 45 nm fabrication technology.
• Intel expects to release an 80-core version
some time in the next 5 years.
• Fabrication technology will become slightly
smaller with 35 nm and possibly 25 nm
technology.

Barry B. Brey
The Future of Microprocessors
• No one can make accurate predictions.
• Success of Intel should continue.
• Change to RISC technology may occur; more
likely improvements to new hyper-threading
technology.
– joint effort by Intel and Hewlett-Packard
• New technology embodies CISC instruction
set of 80X86 family.
– software for the system will survive

Barry B. Brey
• Basic premise is many microprocessors
communicate directly with each other.
– allows parallel processing without any change
to the instruction set or program
• Current superscaler technology uses many
microprocessors; all share same register set.
– new technology contains many microprocessors
– each contains its own register set linked with the
other microprocessors’ registers
• Offers true parallel processing without writing
any special program.

Barry B. Brey
• In 2002, Intel released a new architecture 64
bits in width with a 128-bit data bus.
• Named Itanium; joint venture called EPIC
(Explicitly Parallel Instruction Computing) of
Intel and Hewlett-Packard.
• The Itanium architecture allows greater
parallelism than traditional architectures.
• 128 general-purpose integer and 128 floating-
point registers; 64 predicate registers.
• Many execution units to ensure enough
hardware resources for software.

Barry B. Brey
Figure 1–5a Conceptual views of the 80486, Pentium Pro, Pentium II, Pentium III,

Barry B. Brey
Figure 1–5b Conceptual views of the 80486, Pentium Pro, Pentium II, Pentium III,

Barry B. Brey
• Clock frequencies seemed to have peaked.
• Surge to multiple cores has begun.
• Memory speed a consideration.
– speed of dynamic RAM memory has not
changed for many years.
• Push to static RAM memory will eventually.
increase the performance of the PC.
– main problem with large static RAM is heat
– static RAM operates 50 times faster than dynamic
RAM

Barry B. Brey
• Speed of mass storage another problem.
– transfer speed of hard disk drives has changed
little in past few years
– new technology needed for mass storage
• Flash memory could be solution.
– write speed comparable to hard disk memory
• Flash memory could store the operation
system for common applications.
– would allow operating system to load in a second
or two instead of many seconds now required

Barry B. Brey
1–2 THE MICROPROCESSOR-
BASED PERSONAL COMPUTER
SYSTEM
• Computers have undergone many changes
recently.
• Machines that once filled large areas reduced
to small desktop computer systems because
of the microprocessor.
– although compact, they possess computing power
only dreamed of a few years ago

Barry B. Brey
• Figure 1–6 shows block diagram of the
personal computer.
• Applies to any computer system, from early
mainframe computers to the latest systems.
• Diagram composed of three blocks
interconnected by buses.
– a bus is the set of common connections
that carry the same type of information

Barry B. Brey
Figure 1–6 The block diagram of a microprocessor-based computer system.

Barry B. Brey
The Memory and I/O System
• Memory structure of all Intel-based personal
computers similar.
• Figure 1–7 illustrates memory map of a
personal computer system.
• This map applies to any IBM personal
computer.
– also any IBM-compatible clones in existence

Barry B. Brey
Figure 1–7 The memory map of a personal computer.

Barry B. Brey
• Main memory system divided into three parts:
– TPA (transient program area)
– system area
– XMS (extended memory system)
• Type of microprocessor present determines
whether an extended memory system exists.
• First 1M byte of memory often called the real
or conventional memory system.
– Intel microprocessors designed to function
in this area using real mode operation

Barry B. Brey
• 80286 through the Core2 contain the TPA
(640K bytes) and system area (384K bytes).
– also contain extended memory
– often called AT class machines
• The PS/l and PS/2 by IBM are other versions
of the same basic memory design.
• Also referred to as ISA (industry standard
architecture) or EISA (extended ISA).
• The PS/2 referred to as a micro-channel
architecture or ISA system.
– depending on the model number

Barry B. Brey
• Pentium and ATX class machines feature
addition of the PCI (peripheral component
interconnect) bus.
– now used in all Pentium through Core2 systems
• Extended memory up to 15M bytes in the
80286 and 80386SX; 4095M bytes in 80486
80386DX, Pentium microprocessors.
• The Pentium Pro through Core2 computer
systems have up to 1M less than 4G or 1 M
less than 64G of extended memory.
• Servers tend to use the larger memory map.

Barry B. Brey
• Many 80486 systems use VESA local, VL bus
to interface disk and video to the
microprocessor at the local bus level.
– allows 32-bit interfaces to function at same
clocking speed as the microprocessor
– recent modification supporting 64-bit data bus
has generated little interest
• ISA/EISA standards function at 8 MHz.
• PCI bus is a 32- or 64-bit bus.
– specifically designed to function with the Pentium
through Core2 at a bus speed of 33 MHz.

Barry B. Brey
• Three newer buses have appeared.
• USB (universal serial bus).
– intended to connect peripheral devices to the
microprocessor through a serial data path and
a twisted pair of wires
• Data transfer rates are 10 Mbps for USB1.
• Increase to 480 Mbps in USB2.

Barry B. Brey
• AGP (advanced graphics port) for video
cards.
• The port transfers data between video card
and microprocessor at higher speeds.
– 66 MHz, with 64-bit data path
• Latest AGP speed 8X or 2G bytes/second.
– video subsystem change made to accommodate
new DVD players for the PC.

Barry B. Brey
• Latest new buses are serial ATA interface
(SATA) for hard disk drives; PCI Express bus
for the video card.
• The SATA bus transfers data from PC to hard
disk at rates of 150M bytes per second; 300M
bytes for SATA-2.
– serial ATA standard will eventually reach speeds
of 450M bytes per second
• PCI Express bus video cards operate at 16X
speeds today.

Barry B. Brey
The TPA
• The transient program area (TPA) holds the
DOS (disk operating system) operating
system; other programs that control the
computer system.
– the TPA is a DOS concept and not really
applicable in Windows
– also stores any currently active or inactive DOS
application programs
– length of the TPA is 640K bytes

Barry B. Brey
Figure 1–8 The memory map of the TPA in a personal computer. (Note that this map
will vary between systems.)
• DOS memory map shows
how areas of TPA are used for
system programs, data
and drivers.
– also shows a large area of
memory available for
application programs
– hexadecimal number to left of
each area represents the
memory addresses that begin
and end each data area

Barry B. Brey
• Hexadecimal memory addresses number
each byte of the memory system.
– a hexadecimal number is a number represented
in radix 16 or base 16
– each digit represents a value from 0 to 9 and
from A to F
• Often a hexadecimal number ends with an
H to indicate it is a hexadecimal value.
– 1234H is 1234 hexadecimal
– also represent hexadecimal data as 0xl234 for
a 1234 hexadecimal

Barry B. Brey
• Interrupt vectors access DOS, BIOS (basic
I/O system), and applications.
• Areas contain transient data to access I/O
devices and internal features of the system.
– these are stored in the TPA so they can be
changed as DOS operates

Barry B. Brey
• The IO.SYS loads into the TPA from the disk
whenever an MSDOS system is started.
• IO.SYS contains programs that allow DOS to
use keyboard, video display, printer, and other
I/O devices often found in computers.
• The IO.SYS program links DOS to the
programs stored on the system BIOS ROM.

Barry B. Brey
• Drivers are programs that control installable
I/O devices.
– mouse, disk cache, hand scanner, CD-ROM
memory (Compact Disk Read-Only Memory),
DVD (Digital Versatile Disk), or installable
devices, as well as programs
• Installable drivers control or drive devices or
programs added to the computer system.
• DOS drivers normally have an extension of
.SYS; MOUSE.SYS.
• DOS version 3.2 and later files have an
extension of .EXE; EMM386.EXE.

Barry B. Brey
• Though not used by Windows, still used to
execute DOS applications, even with Win XP.
• Windows uses a file called SYSTEM.INI to
load drivers used by Windows.
• Newer versions of Windows have a registry
added to contain information about the
system and the drivers used.
• You can view the registry with the REGEDIT
program.

Barry B. Brey
• COMMAND.COM (command processor)
controls operation of the computer from the
keyboard when operated in the DOS mode.
• COMMAND.COM processes DOS commands
as they are typed from the keyboard.
• If COMMAND.COM is erased, the computer
cannot be used from the keyboard in DOS
mode.
– never erase COMMAND.COM, IO.SYS, or
MSDOS.SYS to make room for other software
– your computer will not function

Barry B. Brey
The System Area
• Smaller than the TPA; just as important.
• The system area contains programs on read-
only (ROM) or flash memory, and areas of
read/write (RAM) memory for data storage.
• Figure 1–9 shows the system area of a typical
• As with the map of the TPA, this map also
includes the hexadecimal memory addresses
of the various areas.

Barry B. Brey
Figure 1–9 The system area of a typical personal computer.
• First area of system space
contains video display RAM
and video control programs
on ROM or flash memory.
– area starts at location A0000H
and extends to C7FFFH
– size/amount of memory
depends on type of video
display adapter attached

Barry B. Brey
• Display adapters generally have video RAM
at A0000H–AFFFFH.
– stores graphical or bit-mapped data
• Memory at B0000H–BFFFFH stores text data.
• The video BIOS on a ROM or flash memory,
is at locations C0000H–C7FFFH.
– contains programs to control DOS video display
• C8000H–DFFFFH is often open or free.
– used for expanded memory system (EMS) in PC
or XT system; upper memory system in an AT

Barry B. Brey
• Expanded memory system allows a 64K-byte
page frame of memory for use by
applications.
– page frame (D0000H - DFFFFH) used to expand
memory system by switching in pages of memory
from EMS into this range of memory addresses
• Locations E0000H–EFFFFH contain cassette
BASIC on ROM found in early IBM systems.
– often open or free in newer computer systems
• Video system has its own BIOS ROM at
location C0000H.

Barry B. Brey
• System BIOS ROM is located in the top 64K
bytes of the system area (F0000H–FFFFFH).
– controls operation of basic I/O devices connected
to the computer system
– does not control operation of video
• The first part of the system BIOS (F0000H–
F7FFFH) often contains programs that set up
the computer.
• Second part contains procedures that control
the basic I/O system.

Barry B. Brey
Windows Systems
• Modern computers use a different memory
map with Windows than DOS memory maps.
• The Windows memory map in Figure 1–10
has two main areas; a TPA and system area.
• The difference between it and the DOS
memory map are sizes and locations of these
areas.

Barry B. Brey
Figure 1–10 The memory map used by Windows XP.
• TPA is first 2G bytes from
locations 00000000H to
7FFFFFFFH.
• Every Windows program
can use up to 2G bytes of
memory located at linear
addresses 00000000H
through 7FFFFFFFH.
• System area is last 2G
bytes from 80000000H
to FFFFFFFFH.

Barry B. Brey
• Memory system physical map is much
different.
• Every process in a Windows Vista, XP, or
2000 system has its own set of page tables.
• The process can be located anywhere in the
memory, even in noncontiguous pages.
• The operating system assigns physical
memory to application.
– if not enough exists, it uses the hard disk
for any that is not available

Barry B. Brey
I/O Space
• I/O devices allow the microprocessor to
communicate with the outside world.
• I/O (input/output) space in a computer system
extends from I/O port 0000H to port FFFFH.
– I/O port address is similar to a memory address
– instead of memory, it addresses an I/O device
• Figure 1–11 shows the I/O map found in many
personal computer systems.

Barry B. Brey
Figure 1–11 Some I/O locations in a typical personal computer.
• Access to most I/O
devices should always
be made through
Windows, DOS, or
BIOS function calls.
• The map shown is
provided as a guide to
illustrate the I/O space
in the system.

Barry B. Brey
• The area below I/O location 0400H is
considered reserved for system devices
• Area available for expansion extends from I/O
port 0400H through FFFFH.
• Generally, 0000H - 00FFH addresses main
board components; 0100H - 03FFH handles
devices located on plug-in cards or also on
the main board.
• The limitation of I/O addresses between 0000
and 03FFH comes from original standards
specified by IBM for the PC standard.

Barry B. Brey
The Microprocessor
• Called the CPU (central processing unit).
• The controlling element in a computer system.
• Controls memory and I/O through connections
called buses.
– buses select an I/O or memory device, transfer
data between I/O devices or memory and the
microprocessor, control I/O and memory systems
• Memory and I/O controlled via instructions
stored in memory, executed by the
microprocessor.

Barry B. Brey
• Microprocessor performs three main tasks:
– data transfer between itself and the memory or
I/O systems
– simple arithmetic and logic operations
– program flow via simple decisions
• Power of the microprocessor is capability to
execute billions of millions of instructions per
second from a program or software (group of
instructions) stored in the memory system.
– stored programs make the microprocessor and
computer system very powerful devices

Barry B. Brey
• Another powerful feature is the ability to make
simple decisions based upon numerical facts.
– a microprocessor can decide if a number is zero,
positive, and so forth
• These decisions allow the microprocessor to
modify the program flow, so programs appear
to think through these simple decisions.

Barry B. Brey
Buses
• A common group of wires that interconnect
components in a computer system.
• Transfer address, data, & control information
between microprocessor, memory and I/O.
• Three buses exist for this transfer of
information: address, data, and control.
• Figure 1–12 shows how these buses
interconnect various system components.

Barry B. Brey
Figure 1–12 The block diagram of a computer system showing the address, data,
and control bus structure.

Barry B. Brey
• The address bus requests a memory location
from the memory or an I/O location from the
I/O devices.
– if I/O is addressed, the address bus contains a
16-bit I/O address from 0000H through FFFFH.
– if memory is addressed, the bus contains a
memory address, varying in width by type of
microprocessor.
• 64-bit extensions to Pentium provide 40
address pins, allowing up to 1T byte of
memory to be accessed.

Barry B. Brey
• The data bus transfers information between
the microprocessor and its memory and I/O
address space.
• Data transfers vary in size, from 8 bits wide to
64 bits wide in various Intel microprocessors.
– 8088 has an 8-bit data bus that transfers 8 bits
of data at a time
– 8086, 80286, 80386SL, 80386SX, and 80386EX
transfer 16 bits of data
– 80386DX, 80486SX, and 80486DX, 32 bits
– Pentium through Core2 microprocessors transfer
64 bits of data

Barry B. Brey
• Advantage of a wider data bus is speed in
applications using wide data.
• Figure 1–13 shows memory widths and sizes
of 8086 through Core2 microprocessors.
• In all Intel microprocessors family members,
memory is numbered by byte.
• Pentium through Core2 microprocessors
contain a 64-bit-wide data bus.

Barry B. Brey
Figure 1–13a The physical memory systems of the 8086 through the Core2
microprocessors.

Barry B. Brey
Figure 1–13b The physical memory systems of the 8086 through the Core2
microprocessors.

Barry B. Brey
• Control bus lines select and cause memory or
I/O to perform a read or write operation.
• In most computer systems, there are four
control bus connections:
• MRDC (memory read control)
• MWTC (memory write control)
• IORC (I/O read control)
• IOWC (I/O write control).
• overbar indicates the control signal is active-
low; (active when logic zero appears on
control line)

Barry B. Brey
• The microprocessor reads a memory location
by sending the memory an address through
the address bus.
• Next, it sends a memory read control signal to
cause the memory to read data.
• Data read from memory are passed to the
microprocessor through the data bus.
• Whenever a memory write, I/O write, or I/O
read occurs, the same sequence ensues.

Barry B. Brey
1–3 NUMBER SYSTEMS
• Use of a microprocessor requires working
knowledge of numbering systems.
– binary, decimal, and hexadecimal
• This section provides a background for these
numbering systems.
• Conversions are described.
– decimal and binary
– decimal and hexadecimal
– binary and hexadecimal

Barry B. Brey
Digits
• Before converting numbers between bases,
digits of a number system must be
understood.
• First digit in any numbering system is always
zero.
• A decimal (base 10) number is constructed
with 10 digits: 0 through 9.
• A base 8 (octal) number; 8 digits: 0 through 7.
• A base 2 (binary) number; 2 digits: 0 and 1.

Barry B. Brey
• If the base exceeds 10, additional digits use
letters of the alphabet, beginning with an A.
– a base 12 number contains 10 digits: 0 through 9,
followed by A for 10 and B for 11
• Note that a base 10 number does contain a
10 digit.
– a base 8 number does not contain an 8 digit
• Common systems used with computers are
decimal, binary, and hexadecimal (base 16).
– many years ago octal numbers were popular

Barry B. Brey
Positional Notation
• Once digits are understood, larger numbers
are constructed using positional notation.
– position to the left of the units position is the tens
position
– left of tens is the hundreds position, and so forth
• An example is decimal number 132.
– this number has 1 hundred, 3 tens, and 2 units
• Exponential powers of positions are critical for
understanding numbers in other systems.

Barry B. Brey
• Exponential value of each position:
– the units position has a weight of 100, or 1
– tens position a weight of 101, or 10
– hundreds position has a weight of 102, or 100
• Position to the left of the radix (number base)
point is always the units position in system.
– called a decimal point only in the decimal system
– position to left of the binary point always 20, or 1
– position left of the octal point is 80, or 1
• Any number raised to its zero power is always
one (1), or the units position.

Barry B. Brey
• Position to the left of the units position always
the number base raised to the first power.
– in a decimal system, this is 101, or 10
– binary system, it is 21, or 2
– 11 decimal has a different value from 11 binary
• 11 decimal has different value from 11 binary.
– decimal number composed of 1 ten, plus 1 unit;
a value of 11 units
– binary number 11 is composed of 1 two, plus 1
unit: a value of 3 decimal units
– 11 octal has a value of 9 decimal units

Barry B. Brey
• In the decimal system, positions right of the
decimal point have negative powers.
– first digit to the right of the decimal point has a
value of 101, or 0.1.
• In the binary system, the first digit to the right
of the binary point has a value of 21, or 0.5.
• Principles applying to decimal numbers also
generally apply to those in any other system.
• To convert a binary number to decimal, add
weights of each digit to form its decimal
equivalent.

Barry B. Brey
Conversion from Decimal
• To convert from any number base to decimal,
determine the weights or values of each
position of the number.
• Sum the weights to form the decimal
equivalent.

Barry B. Brey
Conversion to Decimal
• Conversions from decimal to other number
systems more difficult to accomplish.
• To convert the whole number portion of a
number to decimal, divide by 1 radix.
• To convert the fractional portion, multiply by
the radix.

Barry B. Brey
Whole Number Conversion from
Decimal
• To convert a decimal whole number to another
number system, divide by the radix and save
remainders as significant digits of the result.
• An algorithm for this conversion:
– divide the decimal number by the radix
(number base)
– save the remainder
(first remainder is the least significant digit)
– repeat steps 1 and 2 until the quotient is zero

Barry B. Brey
• To convert 10 decimal to binary, divide it by 2.
– the result is 5, with a remainder of 0
• First remainder is units position of the result.
– in this example, a 0
• Next, divide the 5 by 2; result is 2, with a
remainder of 1.
– the 1 is the value of the twos (21) position
• Continue division until the quotient is a zero.
• The result is written as 10102 from the bottom
to the top.

Barry B. Brey
• To convert 10 decimal to base 8, divide by 8.
– a 10 decimal is a 12 octal.
• For decimal to hexadecimal, divide by 16.
– remainders will range in value from 0 through 15
– any remainder of 10 through 15 is converted to
letters A through F for the hexadecimal number
– decimal number 109 converts to a 6DH

Barry B. Brey
Converting from a Decimal Fraction
• Conversion is accomplished with multiplication
by the radix.
• Whole number portion of result is saved as a
significant digit of the result.
– fractional remainder again multiplied by the radix
– when the fraction remainder is zero, multiplication
ends
• Some numbers are never-ending (repetend).
– a zero is never a remainder

Barry B. Brey
• Algorithm for conversion from a decimal
fraction:
– multiply the decimal fraction by the radix
(number base).
– save the whole number portion of the result
(even if zero) as a digit; first result is written
immediately to the right of the radix point
– repeat steps 1 and 2, using the fractional part of
step 2 until the fractional part of step 2 is zero
• Same technique converts a decimal fraction
into any number base.

Barry B. Brey
Binary-Coded Hexadecimal
• Binary-coded hexadecimal (BCH) is a
hexadecimal number written each digit is
represented by a 4-bit binary number.
• BCH code allows a binary version of a
hexadecimal number to be written in a form
easily converted between BCH and
hexadecimal.
• Hexadecimal represented by converting digits
to BCH code with a space between each digit.

Barry B. Brey
Complements
• At times, data are stored in complement form
to represent negative numbers.
• Two systems used to represent negative data:
– radix
– radix  1 complement (earliest)

Barry B. Brey
1–4 COMPUTER DATA FORMATS
• Successful programming requires a precise
understanding of data formats.
• Commonly, data appear as ASCII, Unicode,
BCD, signed and unsigned integers, and
floating-point numbers (real numbers).
• Other forms are available but are not
commonly found.

Barry B. Brey
ASCII and Unicode Data
• ASCII (American Standard Code for
Information Interchange) data represent
alphanumeric characters in computer memory.
• Standard ASCII code is a 7-bit code.
– eighth and most significant bit used to hold parity
• If used with a printer, most significant bits are
0 for alphanumeric printing; 1 for graphics.
• In PC, an extended ASCII character set is
selected by placing 1 in the leftmost bit.

Barry B. Brey
• Extended ASCII characters store:
– some foreign letters and punctuation
– Greek & mathematical characters
– box-drawing & other special characters
• Extended characters can vary from one
printer to another.
• ASCII control characters perform control
functions in a computer system.
– clear screen, backspace, line feed, etc.
• Enter control codes through the keyboard.
– hold the Control key while typing a letter

Barry B. Brey
• Many Windows-based applications use the
Unicode system to store alphanumeric data.
– stores each character as 16-bit data
• Codes 0000H–00FFH are the same as
standard ASCII code.
• Remaining codes, 0100H–FFFFH, store all
special characters from many character sets.
• Allows software for Windows to be used in
many countries around the world.
• For complete information on Unicode, visit:
http://www.unicode.org

Barry B. Brey
BCD (Binary-Coded Decimal) Data
• The range of a BCD digit extends from 00002
to 10012, or 0–9 decimal, stored in two forms:
• Stored in packed form:
– packed BCD data stored as two digits per byte;
– used for BCD addition and subtraction in the
instruction set of the microprocessor
• Stored in unpacked form:
– unpacked BCD data stored as one digit per byte
– returned from a keypad or keyboard

Barry B. Brey
• Applications requiring BCD data are point-of-
sales terminals.
– also devices that perform a minimal amount of
simple arithmetic
• If a system requires complex arithmetic, BCD
data are seldom used.
– there is no simple and efficient method of
performing complex BCD arithmetic

Barry B. Brey
Byte-Sized Data
• Stored as unsigned and signed integers.
• Difference in these forms is the weight of the
leftmost bit position.
– value 128 for the unsigned integer
– minus 128 for the signed integer
• In signed integer format, the leftmost bit
represents the sign bit of the number.
– also a weight of minus 128

Barry B. Brey
Figure 1–14 The unsigned and signed bytes illustrating the weights of each binary-bit
position.

Barry B. Brey
• Unsigned integers range 00H to FFH (0–255)
• Signed integers from 128 to 0 to + 127.
• Negative signed numbers represented in this
way are stored in the two’s complement form.
• Evaluating a signed number by using weights
of each bit position is much easier than the
act of two’s complementing a number to find
its value.
– especially true in the world of calculators
designed for programmers

Barry B. Brey
Word-Sized Data
• A word (16-bits) is formed with two bytes of
data.
• The least significant byte always stored in the
lowest-numbered memory location.
• Most significant byte is stored in the highest.
• This method of storing a number is called the
little endian format.

Barry B. Brey
Figure 1–15 The storage format for a 16-bit word in (a) a register and (b) two bytes of
memory.

Barry B. Brey
Figure 1–16 The storage format for a 32-bit word in (a) a register and (b) 4 bytes of
memory.

Barry B. Brey
• Alternate method is called the big endian
format.
• Numbers are stored with the lowest location
containing the most significant data.
• Not used with Intel microprocessors.
• The big endian format is used with the
Motorola family of microprocessors.

Barry B. Brey
Doubleword-Sized Data
• Doubleword-sized data requires four bytes
of memory because it is a 32-bit number.
– appears as a product after a multiplication
– also as a dividend before a division
• Define using the assembler directive define
doubleword(s), or DD.
– also use the DWORD directive in place of DD

Barry B. Brey
Real Numbers
• Since many high-level languages use Intel
microprocessors, real numbers are often
encountered.
• A real, or a floating-point number contains
two parts:
– a mantissa, significand, or fraction
– an exponent.
• A 4-byte number is called single-precision.
• The 8-byte form is called double-precision.

Barry B. Brey
Figure 1–17 The floating-point numbers in (a) single-precision using a bias of 7FH
and (b) double-precision using a bias of 3FFH.

Barry B. Brey
• The assembler can be used to define real
numbers in single- & double-precision forms:
– use the DD directive for single-precision 32-bit
numbers
– use define quadword(s), or DQ to define 64-bit
double-precision real numbers
• Optional directives are REAL4, REAL8, and
REAL10.
– for defining single-, double-, and extended
precision real numbers

Barry B. Brey
SUMMARY
• Mechanical computer age began with the
advent of the abacus in 500 B.C.
• This first mechanical calculator remained
unchanged until 1642, when Blaise Pascal
improved it.
• An early mechanical computer system was
the Analytical Engine developed by Charles
Babbage in 1823.

Barry B. Brey
SUMMARY
• The first electronic calculating machine was
developed during World War II by Konrad
Zuse, an early pioneer of digital electronics.
• The Z3 was used in aircraft and missile
design for the German war effort.
• The first electronic computer, which used
vacuum tubes, was placed into operation in
1943 to break secret German military
codes.
(cont.)

Barry B. Brey
SUMMARY
• The first electronic computer system, the
Colossus, was invented by Alan Turing.
• Its only problem was that the program was
fixed and could not be changed.
• The first general-purpose, programmable
electronic computer system was developed
in 1946 at the University of Pennsylvania.
• This first modern computer was called the
ENIAC (Electronics Numerical Integrator
and Calculator).
(cont.)

Barry B. Brey
SUMMARY
• The first high-level programming language,
called FLOWMATIC.
• Developed for the UNIVAC I computer by
Grace Hopper in the early 1950s.
• This led to FORTRAN and other early
programming languages such as COBOL.
(cont.)

Barry B. Brey
SUMMARY
• The world's first microprocessor, the Intel
4004, was a 4-bit microprocessor-a
programmable controller on a chip-that was
meager by today's standards.
• It addressed a mere 4096 4-bit memory
locations.
• Its instruction set contained only 45
different instructions.
(cont.)

Barry B. Brey
SUMMARY
• Microprocessors that are common today
include the 8086/8088, which were the first
16-bit microprocessors.
• Following these early 16-bit machines were
the 80286, 80386, 80486, Pentium,
Pentium Pro, Pentium II, Pentium III,
Pentium 4, and Core2 processors.
• The architecture has changed from 16 bits
to 32 bits and, with the Itanium, to 64 bits.
(cont.)

Barry B. Brey
SUMMARY
• With each newer version, improvements
followed that increased the processor's
speed and performance.
• From all indications, this process of speed
and performance improvement will
continue.
• Performance increases may not always
come from an increased clock frequency.
(cont.)

Barry B. Brey
SUMMARY
• DOS-based personal computers contain
memory systems that include three main
areas: TPA (transient program area),
system area, and extended memory.
• The TPA hold: application programs, the
operating system, and drivers.
• The system area contains memory used for
video display cards, disk drives, and the
BIOS ROM.
(cont.)

Barry B. Brey
SUMMARY
• The extended memory area is only
available to the 80286 through the Core2
microprocessor in an AT-style or ATX-style
• The Windows-based personal computers
contain memory systems that include two
main areas: TPA and systems area.
(cont.)

Barry B. Brey
SUMMARY
• The 8086/8088 address 1M byte of memory
from locations 00000H-FFFFFH.
• The 80286 and 80386SX address 16M
bytes of memory from 000000H-FFFFFFH.
• The 80386SL addresses 32M bytes of
memory from 0000000H-1FFFFFFH.
• The 80386DX through the Core2 address
4G bytes of memory from locations
00000000H-FFFFFFFFH.
(cont.)

Barry B. Brey
SUMMARY
• Pentium Pro through the Core2 can operate
with a 36-bit address and access up to 64G
bytes of memory from locations
000000000H-FFFFFFFFFH.
• A Pentium 4 or Core2 operating with 64-bit
extensions addresses memory from
locations 0000000000H- FFFFFFFFFFH for
1T byte of memory.
(cont.)

Barry B. Brey
SUMMARY
• All versions of the 8086 through the Core2
microprocessors address 64K bytes of I/O
address space.
• These I/O ports are numbered from 0000H
to FFFFH with I/O ports 0000H-03FFH
reserved for use by the personal computer
system.
• The PCI bus allows ports 0400H-FFFFH.
(cont.)

Barry B. Brey
SUMMARY
• The operating system in early personal
computers was either MSDOS (Microsoft
disk operating system) or PCDOS (personal
computer disk operating system from IBM).
• The operating system performs the task of
operating or controlling the computer
system, along with its I/O devices.
• Modern computers use Microsoft Windows
in place of DOS as an operating system.
(cont.)

Barry B. Brey
SUMMARY
• The microprocessor is the controlling
element in a computer system.
• The micro-processor performs data
transfers, does simple arithmetic and logic
operations, and makes simple decisions.
• The microprocessor executes programs
stored in the memory system to perform
complex operations in short periods of time.
(cont.)

Barry B. Brey
SUMMARY
• All computer systems contain three buses
to control memory and I/O.
• The address bus is used to request a
memory location or I/O device.
• The data bus transfers data between the
microprocessor and its memory and I/O
spaces.
• The control bus controls the memory and
I/O, and requests reading or writing of data.
(cont.)

Barry B. Brey
SUMMARY
• Numbers are converted from any number
base to decimal by noting the weights of
each position.
• The weight of the position to the left of the
radix point is always the units position in
any number system.
• The position to the left of the units position
is always the radix times one.
• Succeeding positions are determined by
multiplying by the radix.
(cont.)

Barry B. Brey
SUMMARY
• The weight of the position to the right of the
radix point is always deter-mined by
dividing by the radix.
• Conversion from a whole decimal number
to any other base is accomplished by di-
viding by the radix.
• Conversion from a fractional decimal
number is accomplished by multiplying by
the radix.
(cont.)

Barry B. Brey
SUMMARY
• Hexadecimal data are represented in
hexadecimal form or in a code called
binary-coded hexadecimal (BCH).
• A binary-coded hexadecimal number is one
that is written with a 4-bit binary number
that represents each hexadecimal digit.
• The ASCII code is used to store alphabetic
or numeric data.
(cont.)

Barry B. Brey
SUMMARY
• The ASCII code is a 7-bit code; it can have
an eighth bit that is used to extend the
character set from 128 codes to 256 codes.
• The carriage return (Enter) code returns the
print head or cursor to the left margin.
• The line feed code moves the cursor or
print head down one line.
• Most modern applications use Unicode,
which contains ASCII at codes 0000H-
00FFH.
(cont.)

Barry B. Brey
SUMMARY
• Binary-coded decimal (BCD) data are
sometimes used in a computer system to
store decimal data.
• These data are stored either in packed (two
digits per byte) or unpacked (one digit per
byte) form.
• Binary data are stored as a byte (8 bits),
word (16 bits), or doubleword (32 bits) in a
computer system.
• These data may be unsigned or signed.
(cont.)

Barry B. Brey
SUMMARY
• Signed negative data are always stored in
the two's complement form.
• Data that are wider than 8 bits are always
stored using the little endian format.
• In 32-bit Visual C++ these data are
represented with char (8 bits), short (16
bits) and int (32 bits).
(cont.)

Barry B. Brey
SUMMARY
• Floating-point data are used in computer
systems to store whole, mixed, and frac-
tional numbers.
• A floating-point number is composed of a
sign, a mantissa, and an exponent.
• The assembler directives DB or BYTE
define bytes, DW or WORD define words,
DD or DWORD define doublewords, and
DQ or QWORD define quadwords.

Microprocessor_pp1a_ppt.ppt

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