1. Problem Solving and Program Design in C Chap. 1 Overview of Computers and Programming Chow-Sing Lin

2. CSIE@NUTN Computers Computer Technology is everywhere!! – Virtually every aspect of your life depends on computers. The computer program’s role in this technology is essential – Without a list of instructions to follow, the computer is virtually useless. One of the most versatile programming languages available today  the C language Dr. Chow-Sing LinProgram Design I - CH12

3. CSIE@NUTN Electronic Computers Then and Now The First Computer built in 1930s by Dr. John Atanasoff and Dr. Clifford Berry at Iowa State University. (ABC) – Atanasoff-Berry-Computer (ABC) – Used in nuclear physics with mathematical computations Dr. Chow-Sing LinProgram Design I - CH13

4. CSIE@NUTN ABC Dr. Chow-Sing LinProgram Design I - CH14

5. CSIE@NUTN ENIAC The first large-scale, general-purpose electronic digital computer – ENIAC – Electronic Numerical Integrator and Computer – Built in 1946 at the Univ. of Pennsylvania with funding from the U.S. army. – Used to compute ballistics tables, predict the weather, make atomic energy calculations – Weight :30 tons; Space: 30 x 50 ft 2 Used vacuum tubes as their basic electronic component. Dr. Chow-Sing LinProgram Design I - CH15

6. CSIE@NUTN ENIAC Dr. Chow-Sing LinProgram Design I - CH16

7. CSIE@NUTN Electronic Technology advance Technological advances in the design and manufacture of electronic components led to new generations of computers – Smaller, faster, and less expensive Nowadays, the entire circuitry of a computer processor can be packaged in a single electronic component, microprocessor chip Dr. Chow-Sing LinProgram Design I - CH17

8. CSIE@NUTN Dr. Chow-Sing LinProgram Design I - CH18 Figure 1.1 The Intel Atom processor chip contains the full circuitry of a central processing unit in an integrated circuit whose small size and low power requirements make it suitable for use in mobile internet devices. (Intel Corporation Pressroom Photo Archives)

9. CSIE@NUTN Computer Category Modern computers are categorized according to their size and performance – Personal computers Used by a single person at a time – Mainframes Large real-time transaction processing systems – Supercomputers The largest capacity and fastest mainframes Intensive computation applications Dr. Chow-Sing LinProgram Design I - CH19

10. CSIE@NUTN Dr. Chow-Sing LinProgram Design I - CH110 1-10 Figure 1.2 (a) Notebook Computer (HP Pavilion dv5©, Courtesy of Hewlett-Packard). (b) Palmtop Computer (iPhone 3G©, Courtesy of Apple, Inc.) (c) Desktop Computer (iMac©, Courtesy of Apple, Inc.)

11. CSIE@NUTN Elements of Computer System Hardware – Perform the necessary computations Central processing unit, monitor, keyboard, mouse, printer, speakers Processing data represented only by 0 and 1 (binary numbers) Software – Programs to solve problems with a computer by providing it with lists of instructions to perform Dr. Chow-Sing LinProgram Design I - CH111

12. CSIE@NUTN Computer Hardware Main Memory Secondary Memory – Hard disks, floppy disk, DVDs, …. Central Processing Unit Input Devices – Keyboards, mouses, touch pads, …. Output Devices – Monitors, printers, and speakers Dr. Chow-Sing LinProgram Design I - CH112

13. CSIE@NUTN Component of a Computer Dr. Chow-Sing LinProgram Design I - CH113

14. CSIE@NUTN Memory Imagine the memory of a computer as an ordered sequence of storage locations  memory cells To store and access information, the computer use an unique address to identify the individual cell. Data and programs are stored in the memory cells – Stored program concept: a program’s instruction must be stored in main memory before they can be executed. Dr. Chow-Sing LinProgram Design I - CH114

15. CSIE@NUTN Memory Layout Dr. Chow-Sing LinProgram Design I - CH115 Figure 1.4 1000 Memory Cells in Main Memory

16. CSIE@NUTN Byte and Bit 0 and 1  one bit 8 bits  1 byte  one character Dr. Chow-Sing LinProgram Design I - CH116

17. CSIE@NUTN Main Memory RAM(random access memory) – Temporary storage of programs and data – Volatile memory Everything in RAM will be lost when the computer is switched off ROM(read-only memory) – Store read-only information permanently within the computer – Not volatile – Store start-up instructions and other critical instructions Dr. Chow-Sing LinProgram Design I - CH117

18. CSIE@NUTN Secondary Memory Computer systems provide storage in addition to main memory for two reasons: 1.Computers need storage permanent or semi- permanent so that information can retained during a power loss or when the computer is turn off. 2.Systems typically store more information than will fit in memory. Hard disk, DVD, magnetic tape, ….. Dr. Chow-Sing LinProgram Design I - CH118

19. CSIE@NUTN Central Processing Unit Play two roles – Coordinating all computer operations – Performing arithmetic and logical operations on data To Process a program stored in main memory, – the CPU retrieves (fetch) each instruction in sequence, interprets the instruction, and then retrieves any data needed to carry out that instruction. – Execute, and store the result back to memory Dr. Chow-Sing LinProgram Design I - CH119

20. CSIE@NUTN Computer Network Link computers together to communicate with one another Dr. Chow-Sing LinProgram Design I - CH120 LAN, Local Area NetworkWAN, Wide Area Network

21. CSIE@NUTN Operating System A middleware (program) between computer hardware and users – Loading the operating system into memory is called booting the computer Operating System is responsible for – Communicate with the computer users – Managing allocation of memory, processor time, and other resources for tasks – Collecting input from other input devices (mouse..) – Conveying program out to other output devices (screen..) – Access/writing data from/to secondary storage Dr. Chow-Sing LinProgram Design I - CH121

22. CSIE@NUTN Application Software Application software is running on top of the operating system – Microsoft office – Google Chrome – Photoshop – ….. Dr. Chow-Sing LinProgram Design I - CH122

23. CSIE@NUTN Computer Languages Machine language – Binary code 001011, 001101, …. – hardly readable by human – CPU dependent Assembly language – More readable, but still hard to learn CLA, ADD A, STA A, …. – One assembly instruction corresponding to one machine language Dr. Chow-Sing LinProgram Design I - CH123

24. CSIE@NUTN Table 1.3 A machine language program fragment and its assembly language equivalent Memory AddressesMachine Language Instructions Assembly Language Instructions 00000000 CLA 0000000100010101ADD A 0000001000010110ADD B 0000001100110101STA A 0000010001110111HLT 00000101?A ? 00000110?B ? Dr. Chow-Sing LinProgram Design I - CH124

25. CSIE@NUTN Computer language (cont’) Write code, run any platform  CPU- independent  high-level language High-level language – Combine algebraic expressions and symbols taken from English Table 1.3 can be replaced by a single high-level language a = a + b ; C, C++, Java, php, C#, Python, …… Dr. Chow-Sing LinProgram Design I - CH125

26. CSIE@NUTN Computer language(cont’) High-level language must be translated into the target computer machine language Source file  object file  executable file  RUN Dr. Chow-Sing LinProgram Design I - CH126

27. CSIE@NUTN Dr. Chow-Sing LinProgram Design I - CH127 Figure 1.12 Entering, Translating, and Running a High-Level Language Program

28. CSIE@NUTN Figure 1.13 Flow of Information During Program Execution Dr. Chow-Sing LinProgram Design I - CH128

29. CSIE@NUTN The Software Development Method 1.Specify the problem requirement – State the problem clearly and unambiguously and to gain a clear understanding of what is required for its solution. 2.Analyze the problem – Identify the problem Input Output Additional requirement and constraints on the solution Dr. Chow-Sing LinProgram Design I - CH129

30. CSIE@NUTN The Software Development Method (cont’) 3.Design the algorithm to solve the problem – Develop a list of steps called an algorithm to solve the problem and to then verify that the algorithm solves the problem as intended. – Writing the algorithm is often the most difficult part of the problem-solving process. – List the major steps, and then refine. – Desk check!! 4.Implement the algorithm – Converting each algorithm step into one or more statements in a programming language, such as C. Dr. Chow-Sing LinProgram Design I - CH130

31. CSIE@NUTN The Software Development Method (cont’) 5.Test and verify the completed program – Testing the completed program to verify that it works as desired. – Run the program several times using different sets of data to ensure its correctness in every aspects. 6.Maintain and update the program – Modifying a program to remove previously undetected errors – keep it up-to-date as government regulations or company policies change. Dr. Chow-Sing LinProgram Design I - CH131

32. CSIE@NUTN Failure is part of the process !! Debugging !! Dr. Chow-Sing LinProgram Design I - CH132

33. CSIE@NUTN Dr. Chow-Sing LinProgram Design I - CH133 Figure 1.14 Miles-to-Kilometers Conversion Program

34. CSIE@NUTN Be sure to read the Chapter Review at the end of each chapter and understand the listed topics ! Do as many implementation exercises as possible ! Dr. Chow-Sing LinProgram Design I - CH134