1 Chapter 1 Introduction to Computers and Information Processing

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Chapter 1

Introduction to Computers

and Information

Processing

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Types of Computer

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Objectives

1. Describe at least two major differences between analog and digital computer. Give examples of analog and digital devices.

2. Differentiate between dedicated, special purpose, and general-purpose computers.

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Major Families

Computers

DigitalAnalog

General

PurposeDedicated

Special

Purpose

Different types of computer are shown in Figure 1.1.

Figure 1.1 Types of Computer

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Major Families (continued)

The major differences between digital and analog computers are summarized in Table 1.1.

Data Digital Computer Analog ComputerRepresented by Digits 0 and 1 Electrical voltagesCalculated by Counting digits Combining and measuring

voltagesControlled by Stored programs Connections on patch-panel

Precision Greater LimitedQuantity of data storage

Large Small

Table 1.1 Major Differences Between Digital and Analog Computers

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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.

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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

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The Computer Revolution

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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.

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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.

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The Information Revolution

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Objectives

1. Differentiate between data and information.

2. Identify the sources of information.

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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

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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

DataData

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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.

Knowledge

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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.Selection

OrganizationManipulation

SelectionOrganizationManipulation

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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.

InformationInformation

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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? OrHow many pounds are being spent on employee salaries?

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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.

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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.

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Information Processing

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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

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Input

Input

Programs

Data

Data - facts entered into the computer.

Programs - specific processing instructions.

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Processing

ProcessingProcessing

Programs

Data and Informationfor current and future use

Programs

Data

Information

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

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Output

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

Information

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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.

StorageStorage

ProgramsData and informationfor current and future use

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What are Computers and Information System

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Objectives

1. Define the terms computer and information system.

2. Recognize the importance of processing a basic level of knowledge, understanding, and skill in using computers and information systems.

3. 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.

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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.

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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

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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.

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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.

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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.

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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.

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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

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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.

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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.

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Function of Information System

Information systems are designed to perform three basic functions:

1. to accept data (input),2. to convert data to information (process), and3. 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).

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Function of Information System (continued)

Input Process Output

DataCustomer specifies Lending policy Interest rate

Data to InformationAlgorithms to convert data into desired information (e.g., customer credit worthiness, recommendation of whether to grant loan or not)

InformationTransformed 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

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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.

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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.

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Why use a Computer?

The purpose of a computer is to transform data into information.

Computers perform three basic functions:

1. performing arithmetic operations on numeric data,

2. testing relationships between data items by logically comparing values, and

3. storing and retrieving data.

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Why use a Computer? (continued)

The advantage of using computers for these functions over humans is that they can use perform them

1. faster2. more accurate, and3. more reliable.

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Major System Units

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Objectives

1. 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.

2. Understand the purpose of software and describe the two main types.

3. Describe the steps involved in transforming data into information.

4. Understand the limitations of computers.

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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).

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What Hardware Makes Up a Computer? (continued)

Secondary Storage

Arithmetic and Logic

Unit

Control Unit

Memory Unit

Input Unit Output Unit

Figure 1.3 Block Diagram of Basic Computer Units

Control

Data

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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

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Components of a Computer System

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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.

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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.

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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.

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There are numerous devices used for input. They are

1. Keyboard2. Pointing devices3. Touch screen

– detect where a computer screen is touched and use this information to initiate an action.

4. Speech recognition (Voice recognition)– The ability of a computer to accept input by understanding the

speech of a user.

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5. 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)

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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.

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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).

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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.

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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.

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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.

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The computer’s 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)

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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

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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 are1. magnetic tape,2. magnetic disk (floppy diskette & hard disk), and3. optical media (CD-ROM & WORM)

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Four main characteristics of all secondary storage media are

1. capacity (total bytes & density),2. access time (data access time & data transfer rate),3. cost, and4. compatibility interface.

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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.

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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.

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What Is Software? (continued)

HardwareHardware

UserUser

System softwareSystem software Application software

Application software

Figure 1.4 The Relationship Among System Software, Application Software, Hardware, and the User

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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.

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How Do Computers Transform Data into Information? (continued)

Terminal Computer Prin ter

S torage

User Input Processing O utput

B

C

01000010

0100001 01000010

0100001

BC

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.

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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.

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Output refers to the results of processing and also describes the act of generating results.

Storage refers to the computer’s 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.

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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.

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How Do We Use Computers?

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Objectives

To identify and describe uses of the computer and indicate the advantages of using a computer in each.

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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

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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.

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Entertainment

Computer-Aided Design

Artificial Intelligence

Education

PersonalComputing

Science, Research, and Engineering

Processand

DeviceControl

Information System / Data Processing

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.

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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.

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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).

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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.

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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).

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Science, research, and engineering

The computer is used as a tool in experimentation, design, and development.

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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.

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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.

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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.

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Entertainment

Every day, computer applications are being designed and created just to entertain us.

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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.

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Knowledged-basedand

expert systemsNatural languages

Simulation of human sensory

capabilitiesRobotics

Area of artificial

intelligneceresearch

Partners inproblem solving

Conversations with computers

Seeing, speaking, hearing, smelling,

etc.

Volunteers for repetitive, dirty, and

dangerous jobs

Figure 1.7 Categories of Artificial Intelligence

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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.

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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.

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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.

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Simulation of human sensory capabilities

This area focuses on equipping computer systems with the capabilities of seeing, hearing, speaking, and felling (touching).

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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.

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Characteristics of Information Processing

System Components

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Objectives

1. Specify the criteria used to categorize computers.

2. Describe the major computer categories.

3. Describe the different types of microcomputers.

4. Distinguish between microcomputers, workstations, minicomputers, mainframes, and supercomputers.

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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.

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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.

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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)

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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.

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Computer Systems Come in all Shapes and Sizes (continued)

According to these criteria, computers are grouped into five size classifications:

1. microcomputers2. workstations3. minicomputers4. mainframes5. supercomputers

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The most distinguishing characteristic of any computer system is its size - not its physical size, but its computing capacity.

Depending on their sophistication, a workstation’s 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.

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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.

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Computing Power

Microcomputer

W orkstation

Minicomputer

Mainframe

Subpercomputer

Other factor used to categorizecomputers

� Architecture� Processing speed� Primary storage� Secondary storage� Output speed� Number of users� Cost

Co

st

Figure 1.8 Because technological advanced have increased computing power and decreased prices, categorical distinctions among computer systems are becoming increasingly blurred

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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.

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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 (PDA’s)· tower PCs.

Continuous improvements in microelectronics and computer technology promise to deliver ever greater processing power in ever smaller units.

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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.

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A typical micro configuration consists of the following:

1. A microcomputer2. A keyboard and a point-and-draw device for input3. A monitor for soft-copy (temporary) output4. A printer for hard-copy (printed) output5. magnetic disk drives for permanent storage of data

and programs

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Micro users have the flexibility to configure their systems with a variety of peripheral devices because of the system’s 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 micro’s bus.

External terminal peripheral devices are interfaced with the processor through either a serial port or a parallel port.

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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.

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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 workstation’s operating system enables it to handle complex processing activities simultaneously and makes it easier to work in harmony with other computers in a network.

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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.

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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

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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.

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30 Order entry terminals (marketing department)

7 Interactive programming

terminals

5 Credit-check terminals

(credit department)

15 Management terminals

Console

Printer

4 Magnetic disk drives

2 Magnetic tape drives

Figure 1.9 A Minicomputer System

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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.

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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

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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).

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Back-end processor Host processor Front-end processor

10 Magnetic disk drives

4 Magnetic tape drives

150 Administrative

terminals(utility billing,

taxex)

2 Consoles

60 Management

terminals

Printer

Printer

10 Dial-up connectionsfor micros 120 Sevices

terminals(fire, police,

sewage)

30 Interactiveprogrammingworkstations

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.