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Title: Chapter 1 Introduction to Computers and Information Systems


1
Chapter 1Introduction to Computers and
Information Processing
2
Types of Computer
3
Objectives
  • Describe at least two major differences between
    analog and digital computer. Give examples of
    analog and digital devices.
  • Differentiate between dedicated, special purpose,
    and general-purpose computers.

4
Major Families
  • Different types of computer are shown in Figure
    1.1.

Figure 1.1 Types of Computer
5
Major Families (continued)
  • The major differences between digital and analog
    computers are summarized in Table 1.1.

Data Digital Computer Analog Computer
Represented by Digits 0 and 1 Electrical voltages
Calculated by Counting digits Combining and measuring voltages
Controlled by Stored programs Connections on patch-panel
Precision Greater Limited
Quantity of data storage Large Small
Table 1.1 Major Differences Between Digital and
Analog Computers
6
Computer for Application
  • Dedicated, special-purpose, and general-purpose
    computers are different in relative efficiency,
    speed, cost, and economy of operation, and
    versatility.
  • Figure 1.2 shows the relationships between
    dedicated, special-purpose, and general-purpose
    computers.

7
Computer for Application (continued)
Higher Lower
Dedicated
Computer
Efficiency, Speed, and Special-Purpose
Economy Computer
Versatility
General-Purpose
Computer
Lower Higher
Figure 1.2 Differences Between Dedicated,
Special-Purpose, and General-Purpose Computers
8
The Computer Revolution
9
The Computer As a Productivity Tool
  • Much of the work done today is done by computers.
  • Computers have automated many difficult,
    dangerous, and even humanly impossible tasks.
  • Automation - when mechanical or electronic
    devices take the place of human observation or
    effort.

10
The Computer As a Productivity Tool (continued)
  • Computers are able to handle the detail and
    leave important things to the human.
  • Computers make it possible to solve difficult
    problems.
  • When used effectively, computers can increase
    productivity at home and at the office.

11
The Information Revolution
12
Objectives
  • Differentiate between data and information.
  •  
  • Identify the sources of information.

13
Data, Knowledge, and Information
  • The information revolution is the result of
    various societal and economic changes brought
    about by rapid increases in the amount of
    available
  • data
  • knowledge
  • information

14
Data
  • Data - (the plural of datum) are raw facts that
    convey little meaning by themselves.
  • Data raw, unorganized facts that describe
    reality.
  • All facts can be considered to be data, including
    such descriptions of reality as sounds and
    images.
  • determining their relevance
  • converting them into information

15
Knowledge
  • Knowledge - the body of rules, guidelines, and
    procedures used to select, organize, and
    manipulate data to make it more useful for a
    specific task.

16
Selection, Organization,and Manipulation
  • Selecting or rejecting facts based on their
    relevancy to a particular task is part of the
    process of converting data into information.
  • Even facts not suited to a particular purpose are
    data.

17
Information
  • Information - data that has been selected,
    organized, and manipulated, and is appropriate
    for a particular purpose.
  • Information is data that has been made more
    useful through the application of knowledge.
  • For example, your first test grade of, say, 93 is
    information to you but is probably regarded only
    as data by your teacher.

18
Sources of Information
  • Information can be of two general types
    quantitative or qualitative.
  • Quantitative information tells how much or how
    many and can be presented in two forms, as
    numerical or graphical information.
  • For example, there are 12 roses in the vase.
  • Quantitative information is used throughout
    businesses.
  • How many units were sold? Or
  • How many pounds are being spent on employee
    salaries?

19
Sources of Information
  • Qualitative information describes something in
    nonquantitative terms.
  • For example, the roses in the vase are red.
  • Qualitative characteristics can be used to
    describe job categories or positions, such as
    marketing manager, graphics designer, or
    programmer.

20
Sources of Information (continued)
  • The two basic sources of information are
  • internal, those gathered within an organization,
    and
  • external, those gathered outside the
    organization.
  • Three common internal sources are
  • Documents (balance sheet, employee file, ),
  • Observations (observing a situation or event),
    and
  • Surveys (form of questionnaires, telephone
    interviews, or personal interviews).
  • Common external sources include surveys, annual
    reports from other organizations, statistics from
    government agencies, trade publications, and
    research reports.

21
Information Processing
22
Information Processing
  • Information processing - the act of using a
    computer to assist in the conversion or
    processing of data into meaningful information.
  • The computer performs four basic functions
  • input
  • processing
  • output
  • storage

23
Information Processing
24
Input
  • Data - facts entered into the computer.
  • Programs - specific processing instructions.

25
Processing
  • Processing - the computer selects, organizes, and
    manipulates the data according to the program
    instructions.

26
Output
  • Information - the converted data that is either
    made immediately available for use or placed in
    storage for future use.

27
Storage
  • Storage - an important function that enables the
    processing activity to be accomplished more
    efficiently by providing a place to hold data,
    programs, and even output until they are needed.

28
What are Computers and Information System
29
Objectives
  • Define the terms computer and information system.
  • Recognize the importance of processing a basic
    level of knowledge, understanding, and skill in
    using computers and information systems.
  • State the purpose of a computer, describe the
    three basic functions that computers perform, and
    explain the advantage of using a computer to
    accomplish them.

30
What are Computers
  • A computer is an electronic device that can
    accept input, process it in a prescribed manner,
    output the results, and store the results for
    later use.
  • A computer is a tool used to process data into
    information.

31
What are Computers (continued)
  • Microelectronics - the miniaturization of the
    components of an electronic circuit.
  • Electronic circuit - a series of components that
    forms a pathway capable of carrying an electrical
    current.
  • Integrated circuit - an electronic circuit placed
    together with a single piece of semiconducting
    material (silicon).
  • Microprocessor - a special type of integrated
    circuit.
  • consists of thousands of electrical circuits
    etched into a very small slice of silicon
  • accepts and processes inputs, and delivers outputs

32
What are Information System
  • A system is any set of components that work
    together to perform a task.
  • An information system is a set of components that
    work together to manage the acquisition, storage,
    manipulation, and distribution of information.

33
Components of an Information Processing System
  • An information processing system components
    consists of
  • hardware
  • software
  • data
  • people
  • procedures
  • All of these elements are organized for a
    specific purpose.

34
Hardware
  • Hardware includes all the physical equipment that
    make up a computer.
  • Hardware - those electronic components of an
    information system that you can see and touch.
  • Also includes telecommunications devices that
    allow input, processing, and output.

35
Software
  • Software is the instructions that cause the
    hardware to do the work.
  • Software - all the instructions that direct the
    operation of the computer system.
  • Includes both the programs and the written
    documentation explaining how to use the
    programs.

36
Data
  • Data provide the basis for the information
    generated by an information system.
  • Data - first input into the information
    processing system, processed, and then output as
    useful information.
  • It is important to recognize two important
    characteristics of data
  • it is reusable
  • if it has been processed into information, that
    information can be considered as data and
    reprocessed into new information as necessary

37
People
  • The single most important component in an
    information processing system is people.
  • People make products, deliver services, solve
    problems, and make decisions.
  • A person who uses computer hardware and software
    to perform a task is often referred to as an end
    user or user.

38
Procedures
  • The methods, policies, and rules that govern the
    use of the information processing system are
    called procedures.
  • Procedures are the instructions that tell a user
    how to operate and use an information system.
  • Some procedures might describe when to run a
    program, while others might describe when an end
    user can use the system, or how the removal of
    outdated data from storage should be handled.

39
Function of Information System
  • Information systems are designed to perform three
    basic functions
  • to accept data (input),
  • to convert data to information (process), and
  • to produce and communicate information in a
    timely fashion to users for decision making
    (output).
  • For example, many banks and other financial
    institutions use information systems to help
    determine whether a customer applying for a loan
    is a good risk (Table 1.2).

40
Function of Information System (continued)
Input Process Output
Data Customer specifies Lending policy Interest rate Data to Information Algorithms to convert data into desired information (e.g., customer credit worthiness, recommendation of whether to grant loan or not) Information Transformed into a form usable by loan officer (e.g., screen display, paper copy)
Table 1.2 Functions of an Information System in
Determining Customer Credit
41
Why Learn About Computers and Information Systems?
  • The shift to a society that emphasizes the
    possession and dissemination of information has
    brought about an increasing use and reliance on
    computers and information systems in many
    professions.
  • To complete in the marketplace you should posses
    a basic level of knowledge and understanding of
    computers and have the ability to effectively use
    them and the information they generate.
  • Possessing knowledge and understanding of
    computers and information systems in combination
    with the ability to use them effectively is
    called computer literacy.

42
Why Learn About Computers and Information
Systems? (continued)
  • Judging the value of information and using the
    information generated wisely is called
    information literacy.
  • There are many levels of ability. These range
    from
  • users who only need to know how to turn the
    computer on and off and use the software required
    by their job.
  • to those who must decide what data should be
    generated and how that data should be processed
  • to those who repair, install, or design
    computers.

43
Why use a Computer?
  • The purpose of a computer is to transform data
    into information.
  • Computers perform three basic functions
  • performing arithmetic operations on numeric data,
  • testing relationships between data items by
    logically comparing values, and
  • storing and retrieving data.

44
Why use a Computer? (continued)
  • The advantage of using computers for these
    functions over humans is that they can use
    perform them
  • faster
  • more accurate, and
  • more reliable.

45
Major System Units
46
Objectives
  • Sketch a simple block diagram of a computer
    system and label the five major units. These are
    the input, central processor, main memory,
    auxiliary storage, and output units.
  • Understand the purpose of software and describe
    the two main types.
  • Describe the steps involved in transforming data
    into information.
  • Understand the limitations of computers.

47
What Hardware Makes Up a Computer?
  • Computer hardware includes the system unit
    (Central Processing Unit and main memory), input
    devices, output devices, and secondary storage
    devices (Figure 1.3).

48
What Hardware Makes Up a Computer? (continued)
Control Data
Figure 1.3 Block Diagram of Basic Computer
Units
49
Components of a Computer System
  • Computer System - a collection of the four basic
    components organized for some purpose.
  • The four basic components are
  • input devices
  • processor unit
  • output devices
  • storage devices

50
Components of a Computer System
51
Four Basic Componentsof a Computer System
  • Input devices - transmit data to the processor
    unit for processing.
  • Processor unit - the brains of a computer
    system contained within the system unit.
  • System unit - the box or case that contains the
    power supply, cooling fans, wires, and other
    devices.

52
Four Basic Componentsof a Computer System
(continued)
  • Output devices - make the converted data
    (information) available for use.
  • Storage devices - hold data and programs for
    current and future use.
  • Primary storage - main memory.
  • Secondary storage - disk and tape.
  • Tertiary storage - disk and tape.

53
Four Basic Componentsof a Computer System
(continued)
  • Input Unit
  • Input refers to the data and instructions entered
    into a computer for processing or to the act of
    entering data, which is often called data entry.
  • An input device is the hardware that allows
    instructions and data to be entered into the
    computer for processing.
  • The input is converted into a digital form the
    computer can use.
  • It is important that data being input into the
    computer be accurate because they are the basis
    for producing the output generated.

54
Four Basic Componentsof a Computer System
(continued)
  • There are numerous devices used for input. They
    are
  • Keyboard
  • Pointing devices
  • Touch screen
  • detect where a computer screen is touched and use
    this information to initiate an action.
  • Speech recognition (Voice recognition)
  • The ability of a computer to accept input by
    understanding the speech of a user.

55
Four Basic Componentsof a Computer System
(continued)
  • Optical recognition
  • The process of using light-sensing equipment to
    scan paper and other media, and translate the
    patterns of light and dark (or color) into a
    digital signal for the computer.
  • Optical scanners are either flatbed scanners or
    handheld scanners.
  • Optical-mark recognition (OMR) (score test
    results)
  • Optical-Bar recognition (OBR)
  • Optical scanners (used in combination with
    graphical software or optical-character
    recognition (OCR) software)

56
Four Basic Componentsof a Computer System
(continued)
  • Output Unit
  • The process of translating machine-readable data
    into a form that can be understood by humans or a
    form that can be read by other machines is called
    output.
  • The information that is the result of processing
    is also referred to as output.
  • An output device is the hardware that enables a
    computer to communicate information to humans or
    other machines so that it may be used.
  • Output that people can read is categorized as
    either hard copy or soft copy.

57
Four Basic Componentsof a Computer System
(continued)
  • Hard copy is a relatively stable and permanent
    form of output, such as paper, that can be read
    immediately or stored and read later.
  • Hard copy output devices include
  • printers
  • plotters
  • computer output microform (COM) devices
    (microfilm or microfiche cards).

58
Four Basic Componentsof a Computer System
(continued)
  • Soft copy, for example, screen-displayed output
    or voice output, is a transient form of output.
  • soft copy output devices include
  • Monitors
  • voice-output
  • An input/output (I/O) device is used both to
    transfer data and instructions to the computer
    and to receive information from the computer.
    Terminals (keyboard and monitor) and disk drives
    are examples of input/output devices.

59
Four Basic Componentsof a Computer System
(continued)
  • Processing Unit
  • The system unit, or housing, contains the major
    components and controls of the computer.
  • Hardware that is extremely attached to the system
    unit is sometimes referred to as a peripheral
    device.
  • A central processing unit (CPU) is comprised of
  • arithmetic-logic unit (ALU), and
  • control unit.

60
Four Basic Componentsof a Computer System
(continued)
  • The ALU handles mathematical and comparison
    operations.
  • The control unit regulates the timing and
    sequence of all processing within a computer.
  • Large system computers may contain many CPUs
    while a microcomputer usually has only one.
  • Large-system computers with more than one CPU
    have the ability to accomplish parallel
    processing, while microcomputers execute one
    instruction after another, called serial
    processing.

61
Four Basic Componentsof a Computer System
(continued)
  • The computers main memory is the internal
    storage unit of a computer where programs and
    data are stored.
  • The two types of main memory are random-access
    memory (RAM) and read-only memory (ROM).
  • Random-access memory (RAM) is the part of main
    memory where data and program instructions are
    held temporarily while being manipulated or
    executed.
  • RAM is
  • Read-write
  • Volatile (when the power to a computer is shut
    off, everything in RAM is lost)

62
Four Basic Componentsof a Computer System
(continued)
  • Read-only memory (ROM) is the part of main memory
    that contain permanently stored instructions that
    tell a computer what to do when it is turned on,
    such as checking that everything is working
    properly and seeing what peripheral equipment is
    attached.
  • ROM is
  • Read only
  • Nonvolatile

63
Four Basic Componentsof a Computer System
(continued)
  • Secondary Storage Unit
  • A secondary storage device is the nonvolatile
    memory used for keeping large amounts of data for
    permanent or large-term storage.
  • Secondary storage media also store backups, or
    copies of data and programs.
  • Three types of secondary-storage media are
  • magnetic tape,
  • magnetic disk (floppy diskette hard disk), and
  • optical media (CD-ROM WORM)

64
Four Basic Componentsof a Computer System
(continued)
  • Four main characteristics of all secondary
    storage media are
  • capacity (total bytes density),
  • access time (data access time data transfer
    rate),
  • cost, and
  • compatibility interface.

65
What Is Software?
  • Software or computer program, are the
    instructions that cause the hardware to do the
    work that you desire.
  • There are two main types of software system
    software and application software.
  • System software directly controls and monitors
    the operation of the computer hardware.
  • Application software allows you to perform a
    specific task or set of tasks.

66
What Is Software? (continued)
  • Tasks include preparing documents, managing data,
    performing numeric calculations, creating graphic
    images, and transferring data between computers
    electronically.
  • The types of application software that perform
    these tasks are word processors, database
    management systems, electronic spreadsheets,
    graphic programs, and communication programs.
  • Application software also includes specialized
    tasks related to such fields as business,
    engineering, science, education, and
    entertainment.
  • Figure 1.4 shows the relationship among system
    software, application software, hardware, and the
    user.

67
What Is Software? (continued)
Figure 1.4 The Relationship Among System
Software, Application Software, Hardware, and the
User
68
How Do Computers Transform Data into Information?
  • Data are transformed into information through a
    series of steps referred to as Information
    processing, or data processing.
  • These steps include (Figure 1.5)
  • input,
  • processing,
  • output, and
  • storage.

69
How Do Computers Transform Data into Information?
(continued)
Figure 1.5 The basic flow of data through a
computer system involves three steps (1) input,
(2) processing, and (3) output. A user enters
data at an input device, and the computer
converts the data to machine-readable form. After
the computer completes that procedure, the
output, in human-readable form, prints out on the
output device. Data can be stored during this
flow.
70
How Do Computers Transform Data into Information?
(continued)
  • Input refers to the data and instructions entered
    into a computer for processing or to the act of
    entering data, which is often called data entry.
  • It is important that data being input into the
    computer be accurate because they are the basis
    for producing the output generated.
  • If the input is incorrect the output will also be
    incorrect, creating a situation referred to as
    garbage in, garbage out (GIGO).
  • Processing involves manipulating data into the
    desired from.

71
How Do Computers Transform Data into Information?
(continued)
  • Output refers to the results of processing and
    also describes the act of generating results.
  • Storage refers to the computers ability to
    maintain data or information for use at a later
    time.
  • A computer has two primary means of storage
    internal storage called main memory, or primary
    storage, and external storage called secondary
    storage.
  • The instructions in a computer program and the
    data they work on must be stored in main memory
    to be executed.
  • Secondary storage preserves programs and data
    permanently or relatively permanently.

72
What Are the Limitation of Computer Use?
  • Computers cannot operate alone.
  • They require humans to identify a problem, decide
    how to solve it, identify and collect the data to
    solve it, design the software to solve it, and
    interpret the information that is obtained.

73
How Do We Use Computers?
74
Objectives
  • To identify and describe uses of the computer and
    indicate the advantages of using a computer in
    each.

75
General categories of Computers
  • The uses of computers can be classified into
    eight general categories
  • Information systems / data processing
  • Personal computing
  • Science, research, and engineering
  • Process / device control
  • Education
  • Computer-aided design
  • Entertainment
  • Artificial intelligence

76
General categories of Computers (continued)
  • Figure 1.6 shows an estimate of how the sum total
    of existing computer capacity is apportioned to
    each of these general categories.

77
General categories of Computers (continued)
Figure 1.6 The Way We Use Computers This pie
chart is an estimate of how existing computer
capacity is distributed among the general
categories of computer usage.
78
General categories of Computers (continued)
  • Information systems / data processing
  • The computer is used to process data and produce
    business information.
  • Example applications include payroll systems,
    airline reservation systems, student registration
    systems, and hospital patient-billing systems.
  • Hardware, software, people, procedures, and data
    combine to create an information system.

79
General categories of Computers (continued)
  • Personal computing
  • The single-user microcomputer is used for a
    variety of business and domestic applications.
  • The family of productivity software is the
    foundation of personal computing in the business
    world and in the home, such as
  • Word processing software enables users to enter
    text, to store it on magnetic storage, to
    manipulate it in preparation for output, and to
    produce a hard copy (printed output).

80
General categories of Computers (continued)
  • Desktop publishing software allows users to
    produce near-typeset-quality copy for
    newsletters, advertisements, and many other
    printing needs, all from the confines of a
    desktop.
  • Spreadsheet software permits users to work with
    the rows and columns of a matrix (or spreadsheet)
    of data.
  • Database software permits users to create and
    maintain a database and extract information from
    the database.
  • Graphics software facilitates the creation and
    management of computer-based images such as pie
    graphs, line drawings, company logos, maps, clip
    art, and blueprints.

81
General categories of Computers (continued)
  • This area of computing is often referred to as
    personal computing.
  • Personal computers can be used as stand-alone
    computer systems or as remote terminal.
  • Dual-function personal computers can be used in
    conjunction with the telephone to transmit data
    to and receive data from an information network.
  • Information networks permit such applications as
    electronic mail (E-mail) and home shopping where
    payment may be made via electronic funds transfer
    (EFT).

82
General categories of Computers (continued)
  • Science, research, and engineering
  • The computer is used as a tool in
    experimentation, design, and development.

83
General categories of Computers (continued)
  • Process / device control
  • Applications that involve process/device control
    accept data in a continuous feedback loop.
  • An automated traffic-control system is a good
    example of he continuous feedback loop in a
    computerized process-control system.
  • In a continuous feedback loop, street sensors
    provide input to a process-control computer
    system about the direction and the volume of
    traffic flow. Based on their feedback, the system
    controls the traffic lights to optimize the flow
    of traffic.

84
General categories of Computers (continued)
  • Education
  • The computer interacts with a student to enhance
    the learning process.
  • Computer-based training (CBT) is having a
    profound impact on traditional modes of
    education.
  • Through interactive computer graphics, a CBT
    system can demonstrate certain concepts more
    effectively than books or teachers.
  • CBT programs can help you to learn keyboarding
    skills, increase your vocabulary, study algebra,
    learn about the makeup of the atom, and practice
    your Russian.

85
General categories of Computers (continued)
  • Computer-aided design
  • Computer-aided design (CAD) is using the computer
    in the design process.
  • CAD systems
  • enable the creation and manipulation of an on
    screen graphic image.
  • provide a sophisticated array of tools enabling
    designers to create three-dimensional objects
    that can be flipped, rotated, resized, viewed in
    detail, examined internally or externally.

86
General categories of Computers (continued)
  • Entertainment
  • Every day, computer applications are being
    designed and created just to entertain us.

87
General categories of Computers (continued)
  • Artificial Intelligence
  • Artificial Intelligence (AI) involves creating
    computer systems with the ability to reason, to
    learn or accumulate knowledge, to strive for
    self-improvement, and to simulate human sensory
    and mechanical capabilities.
  • There are four categories of AI research (Figure
    1.7)
  • knowledge-based and expert systems,
  • natural languages,
  • simulation of human sensory capabilities, and
  • robotics.

88
General categories of Computers (continued)
Figure 1.7 Categories of Artificial Intelligence
89
General categories of Computers (continued)
  • Knowledge-based and expert systems
  • A Knowledge-based system relies on a knowledge
    base that is filled with "rules of thumb"
    (intuition, judgment, and inferences) about a
    specific application area, such as automobile
    repair.
  • Humans can use the knowledge-based system and the
    IF-THEN rules in the knowledge base to help them
    solve a particular problem.
  • Expert systems are the most sophisticated
    implementation of a knowledge-based system.
  • Once the knowledge of one or more human experts
    has been entered to an expert system's knowledge
    base, users can tap this knowledge by interacting
    with the system in much the same way they would
    interact with a human expert in that field.

90
General categories of Computers (continued)
  • Both the user and the computer-based expert
    system ask and respond to each other's questions
    until a problem is resolved.
  • Expert system have been developed to support
    decision makers in a broad range of disciplines,
    including
  • - automobile repair,
    - medical diagnosis,
  • - oil exploration,
    - financial planning,
  • - chemical analysis,
    - surgery,
  • - locomotive repair,
    - weather prediction,
  • - computer repair,
    - trouble-shooting satellites,
  • - computer systems configuration,
  • - operation of nuclear power plants,
  • - newspaper layout,
  • - interpreting government regulations, and
  • - tax preparation.

91
General categories of Computers (continued)
  • Natural languages
  • Natural languages refer to software that enables
    computer systems to accept, interpret, and
    execute instructions in the native, or natural,
    language of the end user.

92
General categories of Computers (continued)
  • Simulation of human sensory capabilities
  • This area focuses on equipping computer systems
    with the capabilities of seeing, hearing,
    speaking, and felling (touching).

93
General categories of Computers (continued)
  • Robotics
  • Robotics is the integration of computers and
    robots.
  • Industrial robots, which are usually equipped
    with an arm and a hand, can be taught to
    perform almost any repetitive manipulative task,
    such as painting a car, screwing on a bolt,
    moving material, and even such complex tasks as
    inspecting a manufactured part for defects.

94
Characteristics of Information Processing System
Components
95
Objectives
  • Specify the criteria used to categorize
    computers.
  •  
  • Describe the major computer categories.
  •  
  • Describe the different types of microcomputers.
  •  
  • Distinguish between microcomputers, workstations,
    minicomputers, mainframes, and supercomputers.

96
Types of Processors
  • Special-purpose - accept a limited set of inputs,
    and process them in a limited set of ways.
  • Embedded - type of special-purpose processors
    that are contained in other products.
  • General-purpose - designed to accept a wide
    variety of inputs, accomplish a wide variety of
    processing activities, and deliver a wide variety
    of outputs.

97
Processing Power
  • We view processing activity as one which first
    requires the accessing of data and instructions
    and then requires the execution of the selection,
    organization, and manipulation operations.
  • Processing power - defined as the speed at which
    this activity can occur.
  • MIPS - millions of instructions per second.
  • MHz - millions of cycles per second.
  • MFLOPS - millions of floating-point operations
    per second.

98
Processing (Main) Memory
  • The capabilities of main memory are a direct
    function of processor access time and storage
    capacity.
  • Storage capacity is measured in
  • Byte - one byte is equal to one character (B)
  • Kilo - 210 - approximately 1 thousand (K)
  • Mega - 220 - approximately 1 million (M)
  • Giga - 230 - approximately 1 billion (G)
  • Tera - 240 - approximately 1 trillion (T)

99
Computer Systems Come in all Shapes and Sizes
  • The criteria for classifying computers include
  • Architecture (design of the internal circuitry),
  • processing speed (MIPS),
  • amount of main memory,
  • capacity of external storage devices,
  • speed of output devices,
  • number of users that can access a system at one
    time, and
  • cost.

100
Computer Systems Come in all Shapes and Sizes
(continued)
  • According to these criteria, computers are
    grouped into five size classifications
  • microcomputers
  • workstations
  • minicomputers
  • mainframes
  • supercomputers

101
Computer Systems Come in all Shapes and Sizes
(continued)
  • The most distinguishing characteristic of any
    computer system is its size - not its physical
    size, but its computing capacity.
  • Depending on their sophistication, a
    workstations computing capacity falls somewhere
    between that of a micro and a main frame.
  • Small computers are classified as microcomputers
    and workstations.
  • Large computers are categorized as
    supercomputers, mainframe computers, and
    minicomputers.

102
Computer Systems Come in all Shapes and Sizes
(continued)
  • All computers, no matter how small or large, have
    the same fundamental capabilities processing,
    storage, input, and output.
  • The number of companies manufacturing a
    particular category of computer increases as the
    size of computer decreases.
  • Figure 1.8 illustrates how various computer
    systems overlap in computing power.

103
Computer Systems Come in all Shapes and Sizes
(continued)
Figure 1.8 Because technological advanced have
increased computing power and decreased prices,
categorical distinctions among computer systems
are becoming increasingly blurred
104
Single-User vs. Multiuser Systems
  • Single-user systems are information processing
    systems primarily designed to support only one
    end user at any one time.
  • Multiuser systems are more powerful in that they
    allow many people to share the same set of data
    and programs without having to duplicate it for
    each individual.

105
Microcomputers Small but Powerful
  • Microcomputers - primarily designed for single
    users, hence their alternative name of personal
    computer (PC) systems microcomputer systems are
    most popular.
  • desktop computer systems
  • laptops
  • notebooks and sub-notebooks
  • palm-size (PDAs)
  • tower PCs.
  • Continuous improvements in microelectronics and
    computer technology promise to deliver ever
    greater processing power in ever smaller units.

106
Microcomputers Small but Powerful (continued)
  • A microcomputer is a computer that is built
    around a single-chip processor called the
    microprocessor.
  • In a microcomputer, the microprocessor, the
    electronic circuitry for handling input/output
    signals from the peripheral devices (keyboard,
    printer, and so on), and the memory chips are
    mounted on a single circuit board called a system
    board, or motherboard.
  • The computer and its peripheral devices are
    called the computer system configuration.

107
Microcomputers Small but Powerful (continued)
  • A typical micro configuration consists of the
    following
  •  
  • A microcomputer
  • A keyboard and a point-and-draw device for input
  • A monitor for soft-copy (temporary) output
  • A printer for hard-copy (printed) output
  • magnetic disk drives for permanent storage of
    data and programs

108
Microcomputers Small but Powerful (continued)
  • Micro users have the flexibility to configure
    their systems with a variety of peripheral
    devices because of the systems open or bus
    architecture.
  • The electrical bus is the path through which the
    processor sends and receives data and commands to
    RAM and all peripheral.
  • A port provides a direct link to the micros bus.
  • External terminal peripheral devices are
    interfaced with the processor through either a
    serial port or a parallel port.
  •  

109
Microcomputers Small but Powerful (continued)
  • Serial ports
  • facilitate the serial transmission of data, one
    bit at a time.
  • provide an interface for low-speed printers and
    modems.
  • Parallel ports
  • facilitate the parallel transmission of data,
    several bits are transmitted simultaneously.
  • provide an interface for high-speed printers,
    magnetic tape backup units, and other computers.
  • Micros can be used as stand-alone computer
    systems, or they can serve as intelligent
    terminals to mainframe computers.
  •  

110
Workstations The Hot Rods of Computing
  • Speed, the sophistication of its input/output
    devices, and its operating system set the
    workstation apart from a PC.
  • The operating system monitors and controls all
    input/output and processing activities within a
    computer system.
  • The workstations operating system enables it to
    handle complex processing activities
    simultaneously and makes it easier to work in
    harmony with other computers in a network.
  •  

111
Workstations The Hot Rods of Computing
(continued)
  • Workstations - single-user systems that provide a
    large amount of processing power and typified by
    high-quality display devices.
  • Common applications for workstations include
    computer-aided design (CAD) and software
    development.
  •  

112
Minis and Mainframes Corporate Workhorses
  • Minicomputers bridge the gap between micros and
    mainframes.
  • Minicomputer is described as the smallest
    computer designed specifically for the multiuser
    environment.
  • Minicomputers - midrange systems that are
    physically smaller and less expensive than
    mainframe systems.
  • are faster and more powerful than some of their
    older mainframe counterparts
  • trend towards smaller computer systems
  • processing power of smaller computer systems has
    dramatically increased
  • advanced telecommunications technologies now
    allow smaller computers to communicate with each
    other

113
Minis and Mainframes Corporate Workhorses
(continued)
  • Minicomputers usually serve as stand-alone
    computer systems (Figure 1.9) for small
    businesses (10 to 400 employees) and as remote
    departmental computer systems.
  •  

114
Minis and Mainframes Corporate Workhorses
(continued)
Figure 1.9 A Minicomputer System
115
Minis and Mainframes Corporate Workhorses
(continued)
  • Mainframes are the category between minicomputers
    and supercomputers.
  • Aside from the obvious differences in processing
    speed, the major difference between minicomputers
    and mainframes is the number of remote terminals
    serviced.
  • A computer servicing more than 200 terminals is
    no longer considered a minicomputers.

116
Minis and Mainframes Corporate Workhorses
(continued)
  • Mainframes - large computer systems that can
    accommodate hundreds of users doing different
    computing tasks
  • applications are large and complex
  • main memory can store hundreds of millions of
    characters
  • used by government agencies, banks, universities,
    and insurance companies

117
Minis and Mainframes Corporate Workhorses
(continued)
  • The operator console in the machine room is used
    to communicate instructions to mini and mainframe
    computer systems.
  • A typical mainframe configuration might have a
    host processor, a front-end processor, and
    perhaps a back-end processor (Figure 1.10).

118
Minis and Mainframes Corporate Workhorses
(continued)
Figure 1.10 Mainframe Computer System
119
Supercomputers Processing Giants
  • Mainframe computers are input/output-bound.
  • In contrast, supercomputers handle the types of
    applications helpful to engineers and scientists.
  • These applications are typically processor-bound
    and require relatively little in the way of input
    or output.

120
Supercomputers Processing Giants (continued)
  • Supercomputers - largest, fastest, and generally
    the most expensive available.
  • main memory can store hundreds of millions of
    characters
  • large businesses and government agencies have
    them
  • popular for advanced scientific calculations
  • used for weather forecasting, engineering, and
    other situations where it is necessary to process
    a lot of data quickly

121
Supercomputers Processing Giants (continued)
  • There are supercomputer applications
  • Simulation of airflow around an airplane at
    different speeds and altitudes.
  • Simulation auto accidents on video screens (Auto
    manufactures).
  • Studying the results of explosions of nuclear
    weapons (Physicists).
  • Hollywood production studios use advanced
    graphics to create special effects for movies and
    TV commercials.
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