1. Gender of Computers? An English teacher was explaining to his students the concept of gender association in the English language. He stated how hurricanes at one time were given feminine names and how ships and planes were usually referred to as "she". One of the students raised his hand and asked - "What gender is a computer"?

2. The teacher wasn't certain which it was, so he divided the class into two groups, males in one, females in the other, and asked them to decide if a computer should be masculine or feminine. Both groups were asked to give four reasons for their recommendation.

3. The group of women concluded that computers should be referred to in the masculine gender because: 1. In order to get their attention, you have to turn them on. 2. They have a lot of data but are still clueless. 3. They are supposed to help you solve your problems, but half the time they ARE the problem. 4. As soon as you commit to one, you realize that, if you had waited a little longer, you could have had a better model.

4. The men, on the other hand, decided that computers should definitely be referred to in the feminine gender because: 1. No one but their creator understands their internal logic. 2. The native language they use to communicate with other computers is incomprehensible to everyone else. 3. Even your smallest mistakes are stored in long- term memory for later retrieval. 4. As soon as you make a commitment to one, you find yourself spending half your paycheck on accessories for it

5. Course Overview Broad overview of Computer Science Text Book: Schneider & Gersting An invitation to CS Selected Topics only Lab exercises alongside Lab Manual

6. CS120: Week 1 Introduction to Computer Science Course Introduction Course overview Laboratory Sessions What is Computer Science? What is an algorithm? History of Computing

7. Course Overview Course Objective Course Outline Assessments and Grading Assessment schedule Variety of topics – Overview CS Usually, lectures on Mondays & Fridays and Labs on Tuesdays and Thursdays

8. Lab Exercises Of the 21 exercises, we will do some 10 only Should attend the lab sessions Lab exercises will be checked Self paced (most could be completed in class) Have lab tutors to help you learn Concept (theory) followed by Lab Bring both the text-book and lab manual to the class

9. An Introduction to Computer Science Objectives: Explain what computer science is and is not. Know and explain definitions of: algorithm, computing agent, and primitive. Trace execution of an algorithm. Determine if a set of steps is an algorithm; explain. Describe and identify sequential, iterative, conditional operations.

10. What is Computer Science Write down the things a computer has. Write down the things you do with a computer. Write down your definition of what computer science is

11. Computer Science is not just: the study of computers programming using computer applications

12. Not just computers circuits disks monitors Keyboards Play stations PDAs

13. Not just programming Using programming languages like Pascal FORTRAN, COBOL COBOL C, C++, C# Java

14. Not just using applications word processors spreadsheets databases Internet Web Browsers

15. Computer Science is the study of algorithms, including their formal mathematical properties (correct, efficient) hardware realizations (to carryout) linguistic realizations (translate) Applications (uses)

16. Organization of the Textbook LEVEL CHAPTER Algorithmic Foundations Hardware Virtual Machine Software Applications Social Issues 654321654321 15 12, 13, 14 8, 9, 10, 11 6, 7 4, 5 2, 3

17. Completing the Loop So, for starters in CS, we learn about all the above six, starting from Algorithmic foundation We identify problems requiring solutions using computers for the good of the society. So there is the ‘Problem to be solved’ that links the ‘society’ and the ‘algorithmic foundation.’

18. What is an algorithm? Informally: An Algorithm is a step by step method for solving a problem. (more formal definition later) We tell the computer how to do something and it does what we tell for us. So what does this imply?

19. Computing agent We do the algorithms A thing that carries out the algorithm is called a computing agent. An unambiguous operation that can be understood and carried out by a computing agent is called primitive operation. When I tell you ‘Study Chapters 1 and 14 in our text for homework’, is it a primitive? How about ‘Build an airplane’?

20. Computing Agent The present day Computer Agent Can accept input Can store information in and retrieve it from memory (unlike us accurately) Can take actions according to algorithm instructions (given to it) Can produce output

21. What is an Algorithm? Formal definition: An algorithm is a well ordered collection of unambiguous and effectively computable operations that produces a result and halts in a finite amount of time.

22. An Algorithm is Well Ordered Each step of the algorithm is executed in the order in which it is written, or else the order is clearly stated. Consider the following example: Design the algorithm that will add two number together and save the sum.

23. An Algorithm is Unambiguous The algorithm must be clearly stated, in terms that the computing agent understands (its primitive operations). Correct this algorithm telling a robot how to take a step to the left, if its only primitive operations are Move_Forward_One_Step, and Turn_Right. Step 1. Turn left Step 2. Move_Forward_One_Step

24. An Algorithm is Effectively Computable It must be possible for the computing agent to perform the operation and produce a result. Example: Find and print the 100 th prime number. If we have the following algorithm, can this be done properly?

25. Example of finding 100 th prime number and print it Step1: Generate a list L of all the prime numbers: L1, L2, L3,…. Step2: Sort the list into ascending order Step3: Print out the 100 th element in the list, L 100 Step 4: Stop

26. An Algorithm Must Halt in a Finite Amount of Time Even if it would take centuries to finish executing the algorithm, there is some point in time when the result would be produced. What is wrong with this algorithm? Step 1. Set X to –1 Step 2. Subtract 1 from X Step 3. If X is not 0, go back to Step 2.

28. Three different things to be done I have three research papers to do in CS120 On Saturday, if it rained I play some indoor games otherwise play an outdoor game. I am taking five courses this semester and in each course there are several assessments (exams, projects, research papers et.). I have a calendar sheet with dates & time for the whole semester. I want to mark on it the assessment dates (due dates, in some cases) Help me draw diagrams to describe these.

29. More about Algorithms The order in which the steps of an algorithm are executed is one of the following: sequential conditional iterative

30. Sequential Order Each step is performed in the order in which it is written (top to bottom). Example: Algorithm for finding a sale price. Step 1. Multiply the regular price by the discount percent. Step 2. Subtract the result of Step 1 from the regular price.

31. Conditional Order Determines whether or not a condition is true; and, based on whether or not it is true, selects the next step to do. Example-- Algorithm for processing a bank check: Step 1. Determine if the amount of the check is greater than the checking account balance. Step 2. If Step 1 is true, print “Overdraft” Step 3. Otherwise, subtract the amount of the check from the balance.

32. Iterative Operation Repeat a set of steps over and over -- also called a “looping” operation. Example: Algorithm for counting the digits in a positive integer N. Step 1. Set the Count to 0 Step 2. Divide N by 10 (dropping any remainder) Step 3. Add 1 to the Count Step 4. If N is greater than 0, repeat steps 2-4

34. 1.4 Historical Overview of Computer Systems Development

35. The Nineteenth Century Inventor of Computers Charles Babbage -- 1830’s idea for a general purpose steam-driven computer programs stored on punched cards four subsystems: memory, mill (ALU), operator (control unit), output programs documented by Ada Augusta, Countess of Lovelace (first programmer)

36. The Birth of Computers 1940-1950 In the United States, the ENIAC was built at the University of PA by J. Presper Eckert and John Mauchly funded by Defense Department for use in World War II completed in 1946 contained 18,000 vacuum tubes and weighed 30 tons

37. 1950 - Present First Generation: 1945-1955 Second Generation: 1955-1965 Third Generation: 1965-1980 Fourth Generation: 1980-?

38. First Generation 1945-1955 ENIAC --- Electronic Numerical Integrator And Computer It consisted of 18,000 vacuum tubes and 1500 relays. It weighted 30 tons and consumed 140 kilowatts of power.

39. Second Generation 1955-1965 vacuum tubes replaced by transistors --- a big leap in computer making. difficulties of programming computers overcome by high level languages –FORTRAN (Formula Translation) –COBOL (Common Business Oriented Language Example: PDP-1 by by Digital Equipment Corporation. Price $120,000

40. Third Generation 1965-1980 wiring problems solved by integrated circuits first small computers built and sold to government –on-board computer for Apollo 11 -- first man on moon –on-board computers for guided missiles

41. Fourth Generation 1980-? microprocessors -- allowed mass production of “throw-away” computers -- “computer on a chip” Apple (1978) -- first affordable commercial microcomputer IBM-PC (1981) -- took major part of market away from Apple Macintosh (1984) -- first graphical interface Microsoft Windows for IBM-PC (1990)

42. Fifth Generation ??? Networked computers (the Internet) Versatile input-output (e.g. touch, speech) Multi-media (graphics and sound) Virtual reality (3-d graphics) Artificial intelligence Neural networks