SSD2: Introduction to Computer Systems

1. SSD2: Introduction to Computer Systems ISS,WHU

2. Unit 1. Computer Systems • 1.1 Overview of Computer Systems • 1.2 Evolution of Computer Systems • 1.3 Data Representation in a Computer System

3. Internet Subsystems of a Computer • Network System • Internet services (email) • Network connections (modems, network cards) • Software System • Operating System (Unix, Mac OS, Microsoft • Windows) • Web browser (Netscape, Internet Explorer) • Office productivity applications (Microsoft • Office, Star Office) • Hardware System • Keyboard • Monitor • System unit

4. Speakers Monitor Printer System unit Keyboard Mouse Hardware System

5. Hardware Components: Peripheral Devices • Equipment added to computer to enhance its functionality • Modify and expand the basic computer system • Examples of peripheral devices: • Keyboard • Monitor • Mouse • Printer • Scanner • Digital Video Camera • Graphic Tablet • Joy Stick

6. Hardware Components:Storage Devices • Optical Disks • CD-ROM • CD-RW • DVD-ROM • Magnetic Disks • Floppy disk • Hard disk (removable & fixed)

7. What is Software? • Software is a set of computer instructions or data. • Software receives input from the user and processes this input through the computer to produce output. • Software directs how the computer interacts with the user. • Software specifies how to process the user's data

8. Users Application Software Operating System Software Hardware System Software System • Two categories: • Operating system software, • Application software

9. Software System • Operating system software, also called system software, is the master controller for all activities that take place within a computer • Examples of OS software: • Microsoft Windows • Unix • Mac OS • Application software is a set of one or more computer programs that helps a personcarry out a task • Examples of application software: • Microsoft Word • Internet Explorer • Macromedia Dreamweaver • Adobe Acrobat Reader

10. Internet • Network connection components: • Network Interface Card (NIC) • Modem • Phone line or cable • Internet Service Provider (ISP) Network System • A network provides connections among computers to enable computers on a network to share data (e.g. documents), hardware (e.g. printers), and software resources (e.g. application programs). • Network users can also send messages to each other. • A network must be secured to protect data from unauthorized usage (e.g. using login name and password to gain access to a network).

11. Basic Computer Model • All computers perform four basic operations • Input Data • Process Data • Store Data • Output Data

12. Basic Operations • Input datais to feed information which can be supplied by any person, environment or other computer. • Processing datais manipulating data by performing calculations, sorting lists of words or numbers, drawing pictures. • Storing datais for future retrieval and processing. Memory holds data that is waiting to be processed, and storage areas hold data permanently until the data is deleted. • Output datais the result produced by a computer, which includes reports, documents, music, graphs and pictures.

13. Categories of Computers • Computers are classified based on their technology, function, physical size, performance and cost. The categories of computers include: • Personal computers • Handheld computers • Mainframes • Supercomputers

14. Personal Computer (PC) • Designed to meet the computing needs of an individual • Desktop computers • Notebook computers

15. Handheld Computer • Designed to fit into a pocket, run on batteries, and be used while you are holding it • Also called a PDA (Personal Digital Assistant) • Send and receive e-mail • Use maps and global positioning • Maintain expense account, contacts, to-do lists, memos, etc. • Make voice calls using cellular service A personal digital assistant (PDA) accepts infoon a touch-sensitivescreen

16. Mainframe Computer • It is a large and expensive computer that is capable of handling requests and passing data simultaneously to many users. • Used by governments and large corporations to provide centralized storage and control • Processes billions of data per second and includes many units where one directs overall operations, a second one handles communication between users, and third searches for requests given by user.

17. Supercomputer • It is the fastest type of computer. • Supercomputers are very expensive and are employed for specialized applications that require immense amounts of mathematical calculations. • It is often used for: • Breaking codes • Modeling weather systems • Simulating nuclear explosions • Research simulations • Capable of performing over 600 billion floating-point operations per second. • Examples: Deep Blue, PARAM 1000, Hitachi's SR2201

18. Evolution of Computers • Needed calculation devices to keep track of accounting for commerce • 1200s—Manual Calculating Devices: the abacus

19. Evolution of Computers (continued) • 1600s—Mechanical Calculators • Used wheels, gears, and counters • To work a mechanical calculator, the operator enters the numbers for a calculation, and then pulls a lever or turns a wheel to carry out the calculation • Example: the Pascaline invented by Blaise Pascal. It used some principles of the abacus, but used wheels to move counters.

20. Evolution of Computers (continued) • 1800s—Punched Cards（punched card ） • Used holes following a specific pattern to represent the instructions given to the machine or stored data • Different program instructions can be stored on separate punched cards, which can be fed through the computing machine repeatedly. • Once punched, the cards were fed into a card reader that used an array of metal rods to electronically read the data from the cards and tabulate the results. This is called the Hollerith Tabulating Machine • Hollerith incorporated The Tabulating Machine better known today as IBM.

21. Evolution of Computers (continued) • Charles Babbage designed a new general-purpose calculating device, the Analytical Engine, which is the ancestor of modern computers. • It included the essential components of present-day computers, which are input, process, storage, and output of data.

22. Evolution of Computers (continued) • 1940s—Vacuum Tubes • Used to control the flow of electrons. Since vacuum tubes responded faster than mechanical components, faster computations were possible. But, the tubes consumed a lot of power and burned out quickly. • The first computer prototype using vacuum tubes was ENIAC (Electronic Numerical Integrator and Computer). It was designed to calculate trajectory tables for the U.S. Army during World War II, but it was not completed until three months after the war.

23. Evolution of Computers (continued) • 1950s—Transistors • Smaller, cheaper, more reliable, and consumed less power than vacuum tubes. • Could perform 200,000 to 250,000 calculations per second.

24. Evolution of Computers (continued) • 1960s—Integrated Circuits • Thin slice of silicon packed with microscopic circuit elements such as wire, transistors, capacitors, and resistors. • Enabled the equivalent of thousands of vacuum tubes or transistors to be packed onto a single miniature chip about the size of your fingernail • Reduces the physical size, weight, and power requirements for devices such as computers

25. Evolution of Computers (continued) • 1970s to Present—Microprocessor • Combined components of a computer on a microchip • Can be manufactured and then programmed for various purposes

26. Evolution of Computers (continued) • Pace of Processor Advancement

27. Applications of Computer Systems • In Education • Multimedia-Facilitated Learning • Simulation-Based Education • Intelligent Machine-Based Training • Interactive Learning • In Business • Supply Chain Management • Project Management • Customer Relationship Management • Sales and Marketing Using Electronic Commerce • Manufacturing Research

28. Applications of Computer Systems • In Entertainment • Movies • Video Games • Music • Digital Photography • Travel • Wearable Computer Systems • Developing new applications of computer systems: • Research at Carnegie Mellon University http://www.cs.cmu.edu/research/projects/ • Research at Massachusetts Institute of Technology Media Labhttp://www.media.mit.edu/

29. Computer Industry • Computer industry encompasses those companies that manufacture handheld computers, personal computers, high-end workstations, servers, mainframes, and supercomputers • Information technology industry(or IT industry), is typically used to refer to the companies that develop, produce, sell, or support computers, software, and computer-related products • IT companies include: • Equipment manufacturers • Chipmakers • Software publishers • Service companies • Retailers

30. Computer Industry (continued) • The 1990s spawned a group of Internet-based companies that came to be called “dot coms”, from the companies’ domain names, which inevitably ended with “.com” and many of the companies even incorporated “.com” into their official company names • Amazon.com was one of the first Internet-based companies

31. Computer Industry (continued) • Governments and private businesses have discovered that they can become much more efficient with a liberal application of computers and other information technologies • As businesses globalize, they encounter new competitors with technological advantages • Bottom line: if your business competitors turn to technology, so must you

32. Careers in Computing • A systems analystinvestigates the requirements of a business or organization, its employees, and its customers in order to plan and implement new or improved computer services • A security specialistanalyzes a computer system’s vulnerability to threats from viruses, worms, unauthorized access, and physical damage • Acomputer programmer designs, codes, and tests computer programs • A quality assurance specialist participates in alpha and beta test cycles of software • A database administrator analyzes a company’s data to determine the most effective way to collect and store it

33. Careers in Computing (continued) • A network specialist/administrator plans, installs, and maintains one or more local area networks • A computer operatortypically works with minicomputers, mainframes, and supercomputers • A computer engineer designs and tests new hardware products, such as computer chips, circuit boards, computers, and peripheral devices • Atechnical support specialistprovides phone or online help to customers of computer companies and software publishers

34. Careers in Computing (continued) • A technical writer creates documentation for large programming projects, and writes the online or printed user manuals that accompany computers, peripheral devices, and software • A computer salesperson, or “sales rep,” sells computers • A Web site designer creates, tests, posts, and modifies Web pages • Amanufacturing technician participates in the fabrication of computer chips, circuit boards, system units, or peripheral devices

35. Careers in Computing (continued) • The U.S. Bureau of Labor Statistics (BLS) projects that the number of jobs in the computer industry will substantially increase between now and 2008 • According to the BLS, the largest increases in available jobs will be for database administrators, computer support specialists, and computer engineers • Over the next few years, economic trends may cause significant changes in the job market • A daily look at in-demand tech skills can be viewed at: http://mshiltonj.com/sm/

36. IT Salaries in the U.S. Source: http://www.bls.gov

37. 1.3 Data Representation in a Computer System • 1.3.1 Bits and Bytes • 1.3.2 Number Systems

38. 1.3.1 Bits and Bytes • Recall computers are made up of electrical components • Data can be represented electronically with electrical components being on or off. • On and off states can be represented using digits 0s and 1s. For example: • 0: Off state • 1: On state • Thus, data can be represented digitally using digits 0 and 1. • 0 and 1 are called binary digits. • Each binary digit is called a bit（二进制位，比特）. • Eight Bits equal to one byte （字节）.

39. Data Representation Using Binary Digits • A piece of data, such as an alphabet letter, may be represented using a sequence of binary digits- 0's and 1's. • There are several types of codes used to represent character data. • Extended ASCII (America Standard Code for Information Interchange) code, • the alphabet letter "a" can be represented using a series of eight binary digits, "01100001."

40. Extended ASCII code • uses eight bits (or one byte) to represent input characters.

41. data representing • All data, including audio, visual, and program instruction data can be represented and stored using a sequence of binary digits, or a sequence of bytes.

42. A file is a collection of data. • In some files, the bits of data directly encode individual letters, numbers, and punctuation symbols that make up words and sentences. • In other files such as an image file, the bits of data need to be computed in order for them to transform to images that we can interpret.

43. A file is a collection of data. • Most applications encode information in specialized ways that are not readable by humans. such as Microsoft Word or PowerPoint • even though Microsoft Word is often used to edit text, a Word document cannot be properly displayed by a simple text editor like Notepad because the document includes information in a format specific to Microsoft Word. • Therefore, it must be opened by Microsoft Word to be read. • Some files have a header section that indicates which format was used to encode the data in order to allow the computer to reassemble the binary data back into the human-readable form of the document.

44. Increasing Need for Bytes

45. In terms of storage, more is better—which • more information in the form of both data and programs that act on that data can be stored. • Corresponding to the growth in storage capacity, memory capacity is also increasing. • Moreover, memory technologies are getting smaller, lighter, and faster, for about the same price.

46. 1.3.2 Number Systems • Decimal: base 10 (digits 0-9) • Binary: base 2 (digits 0-1) • Hexadecimal: base16 (digits 0-9 and A-F) • Each hexadecimal digit represents four binary places. • Hex digit can be used as shorthand for binary notation • One Hex digit four bits • One byte = 8 bits two Hex digits