Copyright 2012 Pearson Education, Inc. Chapter 1 INTRODUCTION TO COMPUTING AND ENGINEERING PROBLEM SOLVING

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Chapter 1

INTRODUCTION

TO COMPUTING

AND ENGINEERING

PROBLEM SOLVING

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Outline

Objectives

1. Historical Perspective

2. Recent Engineering Achievements 3. Computing Systems

4. Data Representation and Storage 5. An Engineering Problem-Solving

Methodology

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Objectives

Introduce computing and engineering problem solving, including:

• A brief history

• Recent engineering achievements

• A discussion of Numbering Systems

• A discussion of hardware and software

• A five-step problem-solving methodology

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Historical Perspective

Charles Babbage, (1792-1871, above)

designed the Analytical Engine

(left) to process decimal numbers.

Augusta Ada Byron (1815-1852, below) wrote the first computer program.

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Charles Babbage, Esq.

1792-1871

• English mathematician.

• Designed the Analytical Engine in the early 1800s.

• Published “Of the Analytical Engine” in 1864.

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Analytical Engine

• Designed to process base ten numbers.

• Consisted of four parts:

– Storage unit

– Processing unit – Input device

– Output device

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Analytical Engine

• Luigi F. Menabrea, French engineer and mathematician, described Babbage’s

vision of a machine capable of solving any problem using:

– Inputs – Outputs

– Programs written on punch cards

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Augusta Ada Byron 1815-1852

• Wrote the English translation of Menabrea’s Sketch of the Analytical Engine.

• Envisioned the multidisciplinary potential of the Analytical Engine.

• Wrote detailed instructions for performing

numerical computations using the Analytical Engine.

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Digital Computers

• ABC (Atanasoff Berry Computer)

• Developed at Iowa State University between 1939 and 1942 by John Atanasoff and Clifford Berry.

• Weighed 700 pounds.

• Executed one instruction every 15 seconds.

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Digital Computers

• ENIAC(Electronic Numerical Integrator And Calculator)

• Developed by research team lead by John Mauchly and J. Presper Eckert during the early 1940s.

• Weighed 30 tons.

• Executed hundreds of instructions every second.

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ENIAC vs. Intel Pentium 4

ENIAC executes hundreds of

operations per second (30 tons)

Today’s processors execute trillions of operations per second and weigh ounces.

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Recent Engineering Achievements

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Recent Engineering Achievements

• Extraterrestrial Explorations

– First manned lunar

landing (July 21, 1969) – Mars Global Surveyor,

Mars Reconnaissance Orbiter, and Mars

Exploration Rovers

• Terrestrial Application Satellites

• Computer Axial

Tomography (CAT) Scanners

• Computer simulations

• Advanced composite materials.

• Speech understanding

• Weather, climate, and global change prediction

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Recent Engineering Achievements

• Digital computers facilitate

multidisciplinary engineering

achievements that:

– Improve our lives.

– Expanded the

possibilities for our future.

• Changing engineering environment requires engineers with:

– Communication skills.

– Skills for working in interdisciplinary teams.

– An awareness of ethic issues and environmental concerns.

– A global perspective.

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Computing Systems

The von Neumann Computing Model

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Computing Systems

• A computing system is a complete working system that includes:

– Hardware – Software

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Hardware

Hardware refers to the physical parts off the computing system that have mass (i.e. they can actually be

touched):

– Computer – Display – Mouse – Printer – …

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Hardware

Jon von Neumann computing model

– Input device(s) – Output device(s) – Memory Unit

– CPU (Central Processing Unit) consisting of:

• Control Unit

• ALU (Arithmetic Logic Unit)

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Software Interface to Computer Hardware

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Software

Computer software refers to programs that reside and execute electronically on the hardware.

– Compilers

– Translate source code

– Operating systems

– Provide the HCI (Human Computer Interface)

– Application programs

– Provide problem solutions

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Building a Program

• Computers only understand machine

language. High-level languages like C++

must be translated to machine language for execution.

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Key Terms

• Source Program

– printable/Readable Program file

• Object Program

– nonprintable machine readable file

• Executable Program

– nonprintable executable code

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Errors in Programs

• Syntax/Parse Errors

– Mistakes with the language.

– Always reported by the compiler

• Linking Errors

– Missing pieces prevent the final assembly of an executable program.

• Run-time Errors

– Occur when program is executing.

– May or may not be reported.

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Logic Errors

• Can be difficult to find.

• Debugging can be time consuming.

– Better tools for find bugs

• It is important to carefully check the output of your programs for errors.

– Even programs that appear to work correctly may have bugs!

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Debugging

• Process of eliminating logic errors (i.e. bugs) from programs.

• User-friendly programming environments such as Microsoft Visual C++ integrate the compiler with

– text processors and code editors

– special tools to help find bugs in programs (debugger) – testing tools

– and much more…

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Data Representation and Storage

00110101001001001010101111101110 10101011111011100011010100100100 11000110110101011111001001001010 10101011111101001001000101110001 00100110111110101010001101010011 01001001001010101111101110001101 10100001101010010010111010011111

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Data Representation and Storage

• Digital computers store information as a sequence of bits (binary digits).

• The value or state of a bit at any given time can be 0 or 1 (off or on).

• Data is stored as a sequence of bytes.

– A byte is a sequence of 8 bits.

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Memory Diagram

Address Space = 8 Word Size = 16

Address Sixteen Bit Word

000 0000101011011101 001 1010001011010100 010 1011010010100101 011 0101001101010101 010 0101000111001110 010 1100110000111010 110 0100011101001001 111 0101110001001000

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Data Representation

• Right most bit is referred to as the least significant bit.

• Left most bit is referred to as the most significant bit.

• Value stored at address 000 is

0000101011011101

₂

= 2781

₁₀

But what does it represent?

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Numbering Systems

• Base ten number system

• Ten decimal digits (0,1,2,3,4,5,6,7,8,9)

• Each digit multiplies a power of ten

– Example:

245

₁₀

= 2*10

²

+ 4*10

¹

+ 5*10

⁰

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Numbering Systems

• Base two (binary) number system

• Two binary digits (0,1)

• Each digit multiplies a power of two

– Example:

10110

₂

= 1*2

⁴

+ 0*2

³

+ 1*2

²

+ 1*2

¹

+ 0*2

⁰

= 116 + 08 + 14 + 12 + 0*1 = 16 + 0 + 4 + 2 + 0

= 22

₁₀

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Numbering Systems

• Base eight number system

• Eight octal digits (0,1,2,3,4,5,6,7)

• Each digit multiplies a power of eight

– Example:

245

₈

= 2*8

²

+ 4*8

¹

+ 5*8

⁰

= 264 + 48 + 5*1 = 128 + 32 + 5

= 165

₈

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Numbering Systems

• Base sixteen number system

• Sixteen hex digits (0,1,2,3,4,5,6,7,8,9,A,B,C,D,E,F)

• Each digit multiplies a power of sixteen

– Example:

2FB

₁₆

= 2*16

²

+ F*16

¹

+ B*16

⁰

= 2256 + F16 + B*1 = 512 + 240 + 11

= 763

₁₀

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Practice with Number Systems

100

₂

= ?

₈

3716

₈

= ?

₂

110100111

₂

= ?

₁₀

3A1B

₁₆

= ?

₂

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Practice with Number Systems

100

₂

= 4

₈

3716

₈

= 011 111 001 110

₂

110100111

₂

= 423

₁₀

3A1B

₁₆

= 0011 1010 0001 1011

₂

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Data Types

• Integer Data Type:

– Often represented in 4 bytes (System Dependent)

– Left most bit is reserved for the sign of the number

– Remaining 31 bits represent the magnitude of the number.

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Data Types

• Representation of data affects the efficiency of arithmetic and logic operations.

• For efficiency, negative integers are often represented in their 2’s complement

form.

• The 2’s complement of an integer is formed by negating all of the bits and adding one.

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Two’s Complement

• Form the 2’s complement

representation for the value -127

₁₀

assuming a word size of 8 bits for simplicity.

127

₁₀

= 01111111

₂

Negate bits: 10000000 Add 1: 10000001

• 2’s complement is 1000 0001

₂

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Two’s Complement

• Add 127

₁₀

to -127

₁₀

01111111

₂

127

₁₀

+ ^10000001

2

 + ^-127

10

= ^00000000

2

= ⁰

10

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