Transcript Chapter 1 Introduction to Computers and Information Systems

Chapter 1
Introduction
to Computers
and
Information
Processing
1
Types of Computer
2
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.
3
Major Families

Different types of computer are shown in Figure 1.1.
Computers
Analog
Digital
Special
General
Purpose
Purpose
Dedicated
Figure 1.1 Types of Computer
4
Major Families (continued)

The major differences between digital and analog
computers are summarized in Table 1.1.
Data
Represented by
Calculated by
Digital Computer
Digits 0 and 1
Counting digits
Controlled by
Stored programs
Analog Computer
Electrical voltages
Combining and measuring
voltages
Connections on patch-panel
Precision
Quantity of data
storage
Greater
Large
Limited
Small
Table 1.1 Major Differences Between Digital and Analog Computers
5
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.
6
Computer for Application (continued)
Higher
Lower
Dedicated
Computer
Efficiency,
Speed, and
Economy
Special-Purpose
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
8
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.
9
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.
10
The Information Revolution
11
Objectives
1. Differentiate between data and information.
2. Identify the sources of information.
12
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.
Data
 determining their relevance
 converting them into information
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Knowledge

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.
15
Selection, Organization,
and Manipulation
Selection
Organization
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.
16
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
17
by your teacher.
Information

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?
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Sources of Information

Qualitative
information
nonquantitative terms.
describes
something
in

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
21
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
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Information Processing
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Input

Data
Input

Data - facts entered into the
computer.
Programs - specific processing
instructions.
Programs
24
Processing
Data and Information
for current and
future use
Programs
Data

Processing - the
computer
selects,
organizes,
and
manipulates the data
according to the
program instructions.
Processing
Programs
Information
25
Output

Output
Information - the converted
data that is either made
immediately available for
use or placed in storage for
future use.
Information
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Storage

Storage
Programs
Data and information
for current and
future use
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.
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What are Computers and
Information System
28
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
31
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.
34
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.
35
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
36
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.
37
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.
2.
3.

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).
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Function of Information System
(continued)
Input
Data
Customer specifies
 Lending policy
 Interest rate
Process
Output
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
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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.
41
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.
42
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.
43
Why use a Computer? (continued)
 The advantage of using computers for these functions
over humans is that they can use perform them
1.
2.
3.
faster
more accurate, and
more reliable.
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Major System Units
45
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.
46
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).
47
What Hardware Makes Up a
Computer? (continued)
Secondary
Storage
Input Unit
Memory
Unit
Output Unit
Control
Unit
Control
Data
Arithmetic
and Logic
Unit
Figure 1.3
Block Diagram of Basic Computer Units
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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
50
Four Basic Components
of 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 Components
of 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.
52
Four Basic Components
of 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.
53
Four Basic Components
of a Computer System (continued)

There are numerous devices used for input. They are
1.
2.
3.
4.
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.
54
Four Basic Components
of a Computer System (continued)
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)
55
Four Basic Components
of 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.
56
Four Basic Components
of 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).
57
Four Basic Components
of 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.
58
Four Basic Components
of 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.
59
Four Basic Components
of 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.
60
Four Basic Components
of a Computer System (continued)

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)
61
Four Basic Components
of 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
62
Four Basic Components
of 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 largeterm storage.
Secondary storage media also store backups, or copies of
data and programs.
Three types of secondary-storage media are
1. magnetic tape,
2. magnetic disk (floppy diskette & hard disk), and
3. optical media (CD-ROM & WORM)
63
Four Basic Components
of a Computer System (continued)
 Four main characteristics of all secondary storage media are
1.
2.
3.
4.
capacity (total bytes & density),
access time (data access time & data transfer rate),
cost, and
compatibility interface.
64
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.
65
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.
66
What Is Software? (continued)
Hardware
System software
Application
software
User
Figure 1.4 The Relationship Among System Software, Application
Software, Hardware, and the User
67
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.
68
How Do Computers Transform Data
into Information? (continued)
Storage
01000010
B
0100001
01000010
C
0100001
B
C
Terminal
User
Input
Computer
Processing
Printer
Output
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
69
form, prints out on the output device. Data can be stored during this flow.
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.
70
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 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.
71
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.
72
How Do We Use Computers?
73
Objectives
 To identify and describe uses of the computer and indicate
the advantages of using a computer in each.
74
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
75
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.
76
General categories of Computers
(continued)
Information System / Data Processing
Entertainment
Computer-Aided Design
Artificial Intelligence
Education
Process
and
Device
Control
Personal
Computing
Science, Research, and Engineering
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.
77
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.
78
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).
79
General categories of Computers
(continued)

Desktop publishing software allows users to produce near-typesetquality 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.
80
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).
81
General categories of Computers
(continued)
Science, research, and engineering
 The computer is used as a tool in experimentation, design,
and development.
82
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.
83
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.
84
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.
85
General categories of Computers
(continued)
Entertainment
 Every day, computer applications are being designed and
created just to entertain us.
86
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.
87
General categories of Computers
(continued)
Area of
artificial
intellignece
research
Knowledged-based
and
expert systems
Partners in
problem solving
Natural languages
Conversations
with computers
Simulation of
human sensory
capabilities
Seeing, speaking,
hearing, smelling,
etc.
Robotics
Volunteers for
repetitive, dirty, and
dangerous jobs
Figure 1.7 Categories of Artificial Intelligence
88
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.
89
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.
90
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.
91
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).
92
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.
93
Characteristics of
Information Processing
System Components
94
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.
95
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.
96
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.
97
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)
98
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.

99
Computer Systems Come in all
Shapes and Sizes (continued)

According to these criteria, computers are grouped
into five size classifications:
1.
2.
3.
4.
5.
microcomputers
workstations
minicomputers
mainframes
supercomputers
100
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 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.
101
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.
102
Computer Systems Come in all
Shapes and Sizes (continued)
Other factor used to categorize
computers
Ÿ
Ÿ
Ÿ
Ÿ
Ÿ
Ÿ
Ÿ
Architecture
Processing speed
Primary storage
Secondary storage
Output speed
Number of users
Cost
Subpercomputer
Mainframe
Minicomputer
W orkstation
Cost
Microcomputer
Computing Power
Figure 1.8 Because technological advanced have increased computing power
and decreased prices, categorical distinctions among computer systems are
becoming increasingly blurred
103
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.
104
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.
105
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.
106
Microcomputers: Small but Powerful
(continued)
 A typical micro configuration consists of the
following:
1.
2.
3.
4.
5.
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
107
Microcomputers: Small but Powerful
(continued)
 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.
108
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.
109
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.
110
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.
111
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
112
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.
113
Minis and Mainframes: Corporate
Workhorses (continued)
7 Interactive
programming
terminals
30 Order entry terminals
(marketing department)
5 Credit-check
terminals
(credit department)
Console
15 Management
terminals
Printer
4 Magnetic disk
drives
2 Magnetic tape
drives
Figure 1.9 A Minicomputer System
114
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.
115
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
116
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 backend processor (Figure 1.10).
117
Minis and Mainframes: Corporate
Workhorses (continued)
10 Dial-up connections
for micros
10 Magnetic
disk drives
120 Sevices
terminals
(fire, police,
sewage)
4 Magnetic
tape drives
Back-end processor
Printer
30 Interactive
programming
workstations
Front-end processor
Host processor
2 Consoles
Printer
60
Management
terminals
Figure 1.10 Mainframe Computer System
150
Administrative
terminals
(utility billing,
taxex)
118
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.
119
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
120
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.
121