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MIS 175 Spring 20021 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 20022 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 20023 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 20024 The Central Tool of Modern Information Systems Figure 4.1 All computers have the same basic components.
MIS 175 Spring 20025 The Central Tool of Modern Information Systems Figure 4.2 Organizations have moved from using large mainframes to using networked PCs.
MIS 175 Spring 20026 The Central Tool of Modern Information Systems Figure 4.3 A timeline of computing
MIS 175 Spring 20027 The Central Tool of Modern Information Systems Figure 4.3 (continued) A timeline of computing
MIS 175 Spring 20028 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 20029 Computers Communicating: Bits And Bytes Figure 4.4 Binary encoding schemes
MIS 175 Spring 200210 A Peek Inside the Computer Figure 4.5 A look inside a computer
MIS 175 Spring 200211 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 200212 A Peek Inside the Computer Microprocessor –Silicon chip embedded with transistors, or semiconductors Figure 4.6 Schematic of how circuits on a chip would be open and closed to represent the letter D in EBCDIC (11000100)
MIS 175 Spring 200213 A Peek Inside the Computer Figure 4.7 What happens inside the CPU in one machine cycle executing the operation 7 + 5
MIS 175 Spring 200214 A Peek Inside the Computer Machine Cycle –CPU’s execution of four functions: Fetch Decode Execute Store
MIS 175 Spring 200215 Time Measurements Functions measured in small fractions of a second “Clock speed” determines the number of the smallest operations performed per second Figure 4.8 Computer time
MIS 175 Spring 200216 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 200217 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 200218 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 200219 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 200220 Input Devices Keyboard Mouse, Trackball, and Track Pad Touch Screen Source Data Input Devices Imaging Speech Recognition
MIS 175 Spring 200221 Input Devices Figure 4.9 Banks use magnetic-ink character recognition (MICR) to automate their input procedures.
MIS 175 Spring 200222 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 200223 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 200224 External Storage Media Magnetic Tapes Magnetic Disks Optical Discs (Compact Discs) Optical Tapes
MIS 175 Spring 200225 External Storage Media Business Considerations of Storage Media –Trade-offs –Modes of Access Sequential Access Direct Access
MIS 175 Spring 200226 External Storage Media Figure 4.11 Characteristics of storage media for business consideration
MIS 175 Spring 200227 External Storage Media Figure 4.12 Sequential and random data organization
MIS 175 Spring 200228 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 200229 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 200230 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 200231 Figure 4.13 PC sales continue to grow. Classification of Computers Personal Computers / Clients Laptop and Handheld Computers
MIS 175 Spring 200232 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 200233 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
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