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

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

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

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

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

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

MIS 175 Spring 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 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 ( )

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

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

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

MIS 175 Spring 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 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 External Storage Media Magnetic Tapes Magnetic Disks Optical Discs (Compact Discs) Optical Tapes

MIS 175 Spring External Storage Media Business Considerations of Storage Media –Trade-offs –Modes of Access Sequential Access Direct Access

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

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

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

MIS 175 Spring 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 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