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					      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     1
     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        2
 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    3
The Central Tool of Modern
  Information Systems




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




Figure 4.2 Organizations have moved from using large mainframes to using
networked PCs.


                            MIS 175 Spring 2002                            5
   The Central Tool of Modern
     Information Systems




Figure 4.3 A timeline of computing


                                MIS 175 Spring 2002   6
    The Central Tool of Modern
      Information Systems




Figure 4.3 (continued) A timeline of computing
                                MIS 175 Spring 2002   7
  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”
                  is “base 2”
  – Binary systemMIS 175 Spring 2002         8
Computers Communicating:
     Bits And Bytes



                              Figure 4.4 Binary encoding
                              schemes




        MIS 175 Spring 2002                           9
  A Peek Inside the Computer




Figure 4.5 A look inside a computer
                              MIS 175 Spring 2002   10
 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    11
 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 2002                              12
  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 2002                           13
 A Peek Inside the Computer

• Machine Cycle
  – CPU’s execution of four functions:
    • Fetch
    • Decode
    • Execute
    • Store



                MIS 175 Spring 2002      14
       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 2002   15
     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                16
             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          17
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     18
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       19
            Input Devices
•   Keyboard
•   Mouse, Trackball, and Track Pad
•   Touch Screen
•   Source Data Input Devices
•   Imaging
•   Speech Recognition


                 MIS 175 Spring 2002   20
                  Input Devices




Figure 4.9 Banks use magnetic-ink character recognition (MICR) to automate
their input procedures.
                            MIS 175 Spring 2002                          21
        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     22
    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            23
     External Storage Media
•   Magnetic Tapes
•   Magnetic Disks
•   Optical Discs (Compact Discs)
•   Optical Tapes




               MIS 175 Spring 2002   24
  External Storage Media
• Business Considerations of
  Storage Media
  – Trade-offs
  – Modes of Access
    • Sequential Access
    • Direct Access




               MIS 175 Spring 2002   25
        External Storage Media




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




Figure 4.12 Sequential and random data organization
                          MIS 175 Spring 2002         27
 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
                  to be stored in a central
   data that needMIS 175 Spring 2002          28
 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        29
 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         30
  Classification of Computers
• Personal Computers / Clients

• Laptop and Handheld Computers




            Figure 4.13 PC sales continue to grow.
                  MIS 175 Spring 2002                31
   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                 32
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              33

				
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