About the Presentations The presentations cover the objectives found in the opening of each chapter. All chapter objectives are listed in the beginning of each presentation. You may customize the presentations to fit your class needs. Some figures from the chapters are included. A complete set of images from the book can be found on the Instructor Resources disc.

2 Invitation to Computer Science 5 th Edition Chapter 1 An Introduction to Computer Science

Invitation to Computer Science, 5th Edition Objectives In this chapter, you will learn about: The definition of computer science Algorithms A brief history of computing Organization of the text 3

Invitation to Computer Science, 5th Edition Introduction Misconceptions –Computer science is: The study of computers The study of how to write computer programs The study of the uses and applications of computers and software 4

Invitation to Computer Science, 5th Edition The Definition of Computer Science Computer science is the study of algorithms, including: –Their formal and mathematical properties –Their hardware realizations –Their linguistic realizations –Their applications 5

Invitation to Computer Science, 5th Edition The Definition of Computer Science (continued) Algorithm –Step-by-step method for accomplishing some task Operations used to construct algorithms –Sequential operations –Conditional operations –Iterative operations 6

Invitation to Computer Science, 5th Edition Figure 1.1 Programming Your DVR. An Example of an Algorithm 7

Invitation to Computer Science, 5th Edition Figure 1.2 Algorithm for Adding Two m-digit Numbers 8

Invitation to Computer Science, 5th Edition The Definition of Computer Science (continued) Why are formal algorithms so important in computer science? –If we can specify an algorithm to solve a problem, then we can automate its solution Computing agent –Machine, robot, person, or thing carrying out the steps of the algorithm 9

Invitation to Computer Science, 5th Edition Algorithms Algorithm –Well-ordered collection of unambiguous and effectively computable operations that, when executed, produces a result and halts in a finite amount of time Ambiguous statements –Go back and do it again (Do what again?) –Start over (From where?) 10

Invitation to Computer Science, 5th Edition Algorithms (continued) Unambiguous operation –Can be understood and carried out directly by the computing agent without further simplification or explanation –Also called primitive operation It is not enough for an operation to be understandable –It must also be doable (effectively computable) by the computing agent 11

Invitation to Computer Science, 5th Edition Algorithms (continued) Algorithm –Result must be produced after the execution of a finite number of operations Infinite loop –Runs forever 12

Invitation to Computer Science, 5th Edition Figure 1.3a A Correct Solution to the Shampooing Problem 13

Invitation to Computer Science, 5th Edition Figure 1.3b Another Correct Solution to the Shampooing Problem 14

Invitation to Computer Science, 5th Edition The Importance of Algorithmic Problem Solving “Computer revolution” of the twentieth and twenty- first centuries –Has enabled us to implement algorithms that mechanize and automate the drudgery of repetitive mental tasks 15

Invitation to Computer Science, 5th Edition A Brief History of Computing The Early Period: Up to 1940 –John Napier invented logarithms as a way to simplify difficult mathematical computations –The first slide rule appeared around 1622 –Blaise Pascal designed and built one of the first mechanical calculators (named the Pascaline) –Gottfried Leibnitz constructed a mechanical calculator called Leibnitz’s Wheel 16

Invitation to Computer Science, 5th Edition Figure 1.4 The Pascaline. One of the Earliest Mechanical Calculators 17

Invitation to Computer Science, 5th Edition The Early Period: Up to 1940 Difference Engine –Could do addition, subtraction, multiplication, and division to six significant digits –Could solve polynomial equations and other complex mathematical problems Babbage’s Analytic Engine –Amazingly similar in design to a modern computer 18

Invitation to Computer Science, 5th Edition The Early Period: Up to 1940 (continued) Herman Hollerith –Designed and built programmable card-processing machines that could automatically read, tally, and sort data entered on punched cards –Founded the Computer Tabulating Recording Company –In 1924, Hollerith’s tabulating machine company changed its name to IBM 19

Invitation to Computer Science, 5th Edition The Birth of Computers: 1940–1950 Mark I –General-purpose, electromechanical programmable computer that used a mix of relays, magnets, and gears to process and store data ENIAC (Electronic Numerical Integrator and Calculator) –Completed in 1946 –First fully electronic general-purpose programmable computer 20

Invitation to Computer Science, 5th Edition The Birth of Computers: 1940–1950 (continued) John Von Neumann –Proposed a radically different computer design based on a model called the stored program computer –Research group at the University of Pennsylvania built one of the first stored program computers, called EDVAC, in

Invitation to Computer Science, 5th Edition The Modern Era: 1950 to the Present First generation of computing –1950 to 1957 Second generation (1957–1965) –Era of FORTRAN and COBOL –The occupation called programmer was born 22

Invitation to Computer Science, 5th Edition The Modern Era: 1950 to the Present (continued) Third generation (1965 to 1975) –Era of the integrated circuit –Birth of the first minicomputer –Birth of the software industry Fourth generation (1975 to 1985) –Saw the appearance of the first microcomputer and computer network –Electronic mail became an important application 23

Invitation to Computer Science, 5th Edition The Modern Era: 1950 to the Present (continued) Fifth generation (1985–?) –Massively parallel processors capable of quadrillions (1015) of computations per second –Handheld digital devices and other types of personal digital assistants (PDAs) –High-resolution graphics for imaging, animation, movie making, and virtual reality 24

Invitation to Computer Science, 5th Edition Figure 1.8 Some of the Major Advancements in Computing 25

Invitation to Computer Science, 5th Edition Organization of the Text 26 Figure 1.9 Organization of the Text into a Six-Layer Hierarchy

Invitation to Computer Science, 5th Edition Summary Computer science is the study of algorithms An algorithm is a well-ordered collection of unambiguous and effectively computable operations that, when executed, produces a result and halts in a finite amount of time If we can specify an algorithm to solve a problem, then we can automate its solution Computers developed from mechanical calculating devices to modern electronic marvels of miniaturization 27