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Learning Objectives

Learning Objectives. When you finish this chapter, you will: Recognize major components of an electronic computer. Understand how the different components work. Know the functions of peripheral equipment. Learning Objectives.

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Learning Objectives

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  1. Learning Objectives • When you finish this chapter, you will: • Recognize major components of an electronic computer. • Understand how the different components work. • Know the functions of peripheral equipment. MIS 175 Spring 2002

  2. Learning Objectives • Be able to classify computers into major categories, and identify their strengths and weaknesses. • Be able to identify and evaluate key criteria when deciding what computers to purchase. MIS 175 Spring 2002

  3. The Central Tool of Modern Information Systems • Four Basic Functions of Computers • Accept data • Process data • Store data and instructions • Output data MIS 175 Spring 2002

  4. Figure 4.1 All computers have the same basic components. The Central Tool of Modern Information Systems MIS 175 Spring 2002

  5. Figure 4.2 Organizations have moved from using large mainframes to using networked PCs. The Central Tool of Modern Information Systems MIS 175 Spring 2002

  6. Figure 4.3 A timeline of computing The Central Tool of Modern Information Systems MIS 175 Spring 2002

  7. Figure 4.3 (continued) A timeline of computing The Central Tool of Modern Information Systems MIS 175 Spring 2002

  8. Computers Communicating: Bits And Bytes • Computer recognizes two states: on or off • Each on or off signal represents a bit (binary digit) • Encoding Schemes • Representation of symbols by unique strings of bits • Counting Bases • Decimal system is “base 10” • Binary system is “base 2” • Used by computers MIS 175 Spring 2002

  9. Computers Communicating: Bits And Bytes Figure 4.4 Binary encoding schemes MIS 175 Spring 2002

  10. Figure 4.5 A look inside a computer A Peek Inside the Computer MIS 175 Spring 2002

  11. A Peek Inside the Computer • The Central Processing Unit (CPU) • The brain of the computer • Microprocessor • Carries signals that execute all processing • Two Components: • Control unit • Arithmetic logic unit (ALU) MIS 175 Spring 2002

  12. Figure 4.6 Schematic of how circuits on a chip would be open and closed to represent the letter D in EBCDIC (11000100) A Peek Inside the Computer • Microprocessor • Silicon chip embedded with transistors, or semiconductors MIS 175 Spring 2002

  13. Figure 4.7 What happens inside the CPU in one machine cycle executing the operation 7 + 5 A Peek Inside the Computer MIS 175 Spring 2002

  14. A Peek Inside the Computer • Machine Cycle • CPU’s execution of four functions: • Fetch • Decode • Execute • Store MIS 175 Spring 2002

  15. Figure 4.8 Computer time Time Measurements Functions measured in small fractions of a second “Clock speed” determines the number of the smallest operations performed per second MIS 175 Spring 2002

  16. Speed Measurements Measured in terms of cycles per second 1 hertz (Hz) = one clock cycle per second 1 MHz (megahertz) = 1,000,000 clock cycles per second (1 million) 1 GHz (gigahertz) = 1,000,000,000 clock cycles per second (1 billion) MIS 175 Spring 2002

  17. Moore’s Law • States that • Chip density will double every 18 months • This has driven incredible decreases in cost per unit of computing power and memory MIS 175 Spring 2002

  18. A Peek Inside the Computer • Memory • CPU Registers (part of the CPU) • Internal Memory • Random access memory (RAM) • Read-only memory (ROM) MIS 175 Spring 2002

  19. A Peek Inside the Computer • Computer Power • Clock rate (measured in cycles per second) • Amount of information the CPU can process in each cycle • This is determined by the word length and bus size • Effective speed determined only by combination of both factors MIS 175 Spring 2002

  20. Input Devices • Keyboard • Mouse, Trackball, and Track Pad • Touch Screen • Source Data Input Devices • Imaging • Speech Recognition MIS 175 Spring 2002

  21. Figure 4.9 Banks use magnetic-ink character recognition (MICR) to automate their input procedures. Input Devices MIS 175 Spring 2002

  22. Output Devices • Soft-Copy Output Devices • Cathode-Ray Tube (CRT) Monitor • Flat-Panel Monitor • Speech Output • Hardcopy Output Devices • Nonimpact Printers (most common) • Impact Printers MIS 175 Spring 2002

  23. External Storage Media External Memory (Storage) • Magnetic disks, magnetic tapes, optical discs • Important Properties to Consider • Capacity • Speed • Cost • Reliability and permanence MIS 175 Spring 2002

  24. External Storage Media • Magnetic Tapes • Magnetic Disks • Optical Discs (Compact Discs) • Optical Tapes MIS 175 Spring 2002

  25. External Storage Media • Business Considerations of Storage Media • Trade-offs • Modes of Access • Sequential Access • Direct Access MIS 175 Spring 2002

  26. Figure 4.11 Characteristics of storage media for business consideration External Storage Media MIS 175 Spring 2002

  27. Figure 4.12 Sequential and random data organization External Storage Media MIS 175 Spring 2002

  28. Classification of Computers • Supercomputers • The largest, most powerful, and most expensive • Used by universities, research institutions, large corporations, and the military • Mainframe Computers • Less powerful and less expensive than supercomputers • Used by businesses with large amounts of data that need to be stored in a central computer MIS 175 Spring 2002

  29. Classification of Computers • Minicomputer • Often used as the host computer in a network of smaller computers • Priced in the tens of thousands to a few hundred thousand dollars • Manufacturers: Compaq (VAX), IBM (AS/400), and Hewlett-Packard MIS 175 Spring 2002

  30. Classification of Computers • Servers • Minicomputers used for specialized purposes on a network • Example: file server, printer server, database server, web server • Optimized for processing tasks and I/O with other computers MIS 175 Spring 2002

  31. Figure 4.13 PC sales continue to grow. Classification of Computers • Personal Computers / Clients • Laptop and Handheld Computers MIS 175 Spring 2002

  32. Importance of Standards • Compatibility • Software and peripheral devices from one computer can be used with another computer. • In a networked environment, computers need to communicate to share databases and other computing resources. • In addition to power and cost, compatibility is an extremely important factor in purchasing decisions. MIS 175 Spring 2002

  33. Considerations in Purchasing Hardware • What should you consider when buying personal computers? • Power -- speed, size of memory, storage capacity • Expansion and upgrade capability • Ports for external devices like printers, hard disks, communication devices • Ergonomics: Keyboard, Monitor • Vendor reliability, warranty policy, vendor support MIS 175 Spring 2002

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