1 Lecture-I CSIT-120 Spring 2001 Introducing the Course Syllabus Introduction to Computers Introduction to Computer Science Information, Algorithms and Programs Information Technology Computer as an idiot Examples of Algorithms

2 Introducing the Course Welcome to CSIT120 Computer Science Overview This course aims at doing a comprehensive survey of the field of computer science The textbook is “Computer Science: An Overview”, by J. Glenn Brookshear, Addison Wesley

Introduction Let us go over the syllabus and then start the introductory topics

Topics 1.Introduction to Computers, Main Components and Operating Systems 2.Algorithms and Problem Solving 3.Data Storage and Manipulation 4.Programming 5.Software Engineering 6.Data Structures 7.Computer Applications and Ethics in Computing

Introducing Computers Computer is a machine capable of performing computations Computer can take logical decisions to choose between alternatives, something we do every day

6 Decisions….. If it is raining, take the umbrella else do not take the umbrella If I am a hard working student, I should continue in CSIT120 else drop it If my car is disabled then: If the Greyhound bus can take me to Buffalo before the program starts, I am all set else call to cancel my presentation

History of Computers 2000BC Abacus used for computations 1890 Hollerith designs electronic census reader and later founds IBM 1939 J. Atanasoff designs first electronic digital computer 1946 Von Neumann proposes stored program computer 1977 Apple Computer launched 1981 IBM PC launched

History of Computers 1970 UNIX first version released 1971 Pascal language developed 1972 C language developed 1973 Part of UNIX implemented in C 1985 C re-implemented as C C++ standard released

Types of Computers Microcomputers (PDA, Lap-top, Desk-top and Workstation computers) Minicomputers and Mainframes Supercomputers

Hardware of Computers Computers consist of YCPU (Data path and control) YMemory (Primary/Secondary) YInput devices YOutput devices What is a CD-Drive? What is a SIMM? What is a modem?

11 Computer Science Computer science has the same relation to computers that astronomy does to telescopes. ~ Donald Knuth What does this mean? Is computer science study of computers or something else? Is astronomy study of telescopes or something else?

12 Computer Science Computer Science is a relatively new discipline It has advanced rapidly and growth of fields within computer science is enormous Look at programming languages and techniques, computer networks, even the speed and power of PC’s

13 Computer Science Formal Defintion: “It is a science of information handling and representation” Another Definitions: “Computer Science is the study of those algorithms that transform information” What is an algorithm?

14 Information, Algorithms and Programs An algorithm is a precise sequence of steps that can be automated Thus an algorithm can be entered into the computer using any programming language, resulting in a “program” A computer can take logical decisions during execution of the programs e.g. if Temp<10 don’t go jogging

15 Algorithms Algorithms are computational procedures that are guaranteed to work, i.e. solve a problem and do it in a finite amount of time An algorithm should use the computing resources efficientlyincluding the processor, memory and peripherals Once an algorithm is developed, it “locks intelligence” and one can use it without caring about how it works

16 Information Technology Due to the fact that computers can handle and process information, the use of computers has spread to all fields of human knowledge. This is the IT of CSIT code Computer can process sound and video data, financial and commerce data and scientific data, all with automated procedures

17 Computer as an idiot A computer will only do whatever it is told to do, it is a faithful slave. If you ask the computer to do something, it will do it, whether right or wrong If your program runs well but contains logical errors, you will get wrong results If your program is ok but you feed wrong information, you will get wrong results

18 Computer as an idiot Computers are very picky and small mistakes will confuse them easily When you develop your Visual C++ programs, you will find out that the above statement is very true A minor mistake, such as an additional comma or missing semicolon will drive the compiler crazy

19 Examples of Algorithms Develop an algorithm to add three numbers together: –Add first two numbers; store the result at a temporary place –Recall the result from previous step and add the third number to it