INTRODUCTION TO INFORMATION SYSTEM
DIT 0100
1
, Table of Contents
Chapter One: Computer and computing infrastructure............................................................................................5
Description of terms and concepts.......................................................................................................................5
Reasons for changing from manual to computerized or electronic systems........................................................6
The computing concept........................................................................................................................................7
The Computer System..........................................................................................................................................7
Central processing unit....................................................................................................................................9
Primary storage..............................................................................................................................................10
Data representation in a computer.................................................................................................................11
Chapter Two: Input and Output technologies........................................................................................................14
Computer Input..................................................................................................................................................14
Direct data input devices................................................................................................................................14
Indirect data devices......................................................................................................................................17
Computer Output devices..................................................................................................................................18
Backing Storage.............................................................................................................................................22
Factors to consider when selecting hardware................................................................................................27
Chapter Three: Software........................................................................................................................................28
Application Software Packages and Productivity Software..............................................................................33
Software package A prewritten, precoded, commercially available set of programs that eliminates the need to
write software programs for certain functions...................................................................................................33
Spreadsheets...................................................................................................................................................36
Data Management Software..........................................................................................................................37
Presentation Graphics...................................................................................................................................38
Integrated Software Packages and Software Suites......................................................................................38
Chapter Four: Data Processing..............................................................................................................................41
Data Processing..................................................................................................................................................41
Hardcopy............................................................................................................................................................41
Softcopy.............................................................................................................................................................41
Data processing Cycle/System...........................................................................................................................42
Figure 4.0. The data processing cycle................................................................................................................42
The table below shows sample data processing cycle activities........................................................................42
Functions of stages in the data processing cycle...........................................................................................43
Processing Components.....................................................................................................................................43
Output Component.............................................................................................................................................43
Storage Component............................................................................................................................................43
Data Processing Methods...................................................................................................................................43
i. Manual data processing......................................................................................................................................43
Factors That Influence Selection Of Data Processing Method......................................................................44
Manual Data Processing................................................................................................................................44
Mechanical.....................................................................................................................................................45
Characteristics....................................................................................................................................................45
Advantages.........................................................................................................................................................45
Disadvantages....................................................................................................................................................45
Electromechanical Data processing...............................................................................................................45
Advantages.........................................................................................................................................................46
Disadvantages....................................................................................................................................................46
Electronic Data processing Systems..............................................................................................................46
Characteristics....................................................................................................................................................46
2
, Advantages.........................................................................................................................................................46
Disadvantages....................................................................................................................................................46
Why data processing is necessary......................................................................................................................46
Data processing techniques............................................................................................................................47
Batch Processing / Off-Line Processing............................................................................................................47
Characteristics................................................................................................................................................47
Advantages.....................................................................................................................................................47
Disadvantages....................................................................................................................................................47
Application.........................................................................................................................................................48
Time Sharing......................................................................................................................................................49
Characteristics....................................................................................................................................................49
Summary................................................................................................................................................................51
Chapter Five: File design and organization...........................................................................................................52
The data hierarchy..............................................................................................................................................52
Factors to consider in file design...................................................................................................................54
Storage media.........................................................................................................................................................54
Serial files......................................................................................................................................................55
Sequential file................................................................................................................................................55
Indexed sequential.........................................................................................................................................55
Direct access/Random/immediate access......................................................................................................56
Applications of file design/organisations sequential.....................................................................................56
Application.............................................................................................................................................................57
Merits.....................................................................................................................................................................57
Demerits.................................................................................................................................................................57
Application.............................................................................................................................................................57
Application.............................................................................................................................................................57
Chapter Six: Information systems used in Organisations......................................................................................58
Major Types of Systems in Organizations.........................................................................................................58
MIS summarize and report on the company’s basic operations. The basic transaction data from TPS are
compressed and are usually presented in long reports that are produced on a regular schedule. The following
figure shows how a typical MIS transforms transaction level data from inventory, production, and accounting
into MIS files that are used to provide managers with reports. The figure below shows a sample report from this
system....................................................................................................................................................................63
Chapter Seven: Communication Networks............................................................................................................69
Network: A network is basically two or more computers connected through a cable or wire or space which
share resources. Network software controls how the computers communicate....................................................69
Components and Functions of a Telecommunications System.........................................................................69
Types of Signals: Analog and Digital............................................................................................................71
Data transmission modes between devices........................................................................................................72
There are three ways by which data signals can be relayed between communicating devices. These ways are:. 72
Simplex transmission.............................................................................................................................................72
Half duplex transmission.......................................................................................................................................72
Full duplex transmission........................................................................................................................................72
Simplex transmission.....................................................................................................................................72
Half-Duplex...................................................................................................................................................72
Full Duplex....................................................................................................................................................72
Scope of Networks.............................................................................................................................................73
Local Area Network.......................................................................................................................................73
Wide Area Network.......................................................................................................................................73
Basic Connectivity Components........................................................................................................................74
3
, a) Network Adapters..............................................................................................................................................74
b) Network Cables..................................................................................................................................................75
i. Twisted-Pair Cable.............................................................................................................................................75
ii. Coaxial Cable....................................................................................................................................................75
Coaxial cable consists of a copper wire core surrounded by insulation, a braided metal shielding, and an outer
cover. The core of a coaxial cable carries the electronic signals that make up the data. This wire core can be
either solid or stranded. There are two types of coaxial cable: ThinNet coaxial cable (10Base2) and ThickNet
coaxial cable (10Base5). Coaxial cabling is a good choice when transmitting data over long distances and for
reliably supporting higher data rates when using less sophisticated equipment....................................................75
iii. Fiber-Optic Cable.............................................................................................................................................76
Fiber-optic cable uses optical fibers to carry digital data signals in the form of modulated pulses of light.
Because fiber-optic cable carries no electrical impulses, the signal cannot be tapped and its data cannot be
stolen. Fiber-optic cable is good for very high-speed, high-capacity data transmission because the signal is
transmitted very quickly and with very little interference.....................................................................................76
Selecting Cables.................................................................................................................................................76
Wireless Communication Devices.....................................................................................................................76
i. Infrared Transmission.........................................................................................................................................77
ii. Narrowband Radio Transmission......................................................................................................................77
Network Topologies...........................................................................................................................................77
i. Bus Topology......................................................................................................................................................78
ii. Star Topology.....................................................................................................................................................78
iii. Ring Topology...................................................................................................................................................78
iv. Mesh Topology..................................................................................................................................................79
v. Hybrid Topologies.............................................................................................................................................80
a) Star-Bus.............................................................................................................................................................80
b) Star-Ring............................................................................................................................................................80
Types of Data Transmissions.................................................................................................................................81
Unicast...................................................................................................................................................................81
Broadcast................................................................................................................................................................81
Multicast................................................................................................................................................................81
Chapter Eight: The Internet...................................................................................................................................83
What Is the Internet?.........................................................................................................................................83
4
DIT 0100
1
, Table of Contents
Chapter One: Computer and computing infrastructure............................................................................................5
Description of terms and concepts.......................................................................................................................5
Reasons for changing from manual to computerized or electronic systems........................................................6
The computing concept........................................................................................................................................7
The Computer System..........................................................................................................................................7
Central processing unit....................................................................................................................................9
Primary storage..............................................................................................................................................10
Data representation in a computer.................................................................................................................11
Chapter Two: Input and Output technologies........................................................................................................14
Computer Input..................................................................................................................................................14
Direct data input devices................................................................................................................................14
Indirect data devices......................................................................................................................................17
Computer Output devices..................................................................................................................................18
Backing Storage.............................................................................................................................................22
Factors to consider when selecting hardware................................................................................................27
Chapter Three: Software........................................................................................................................................28
Application Software Packages and Productivity Software..............................................................................33
Software package A prewritten, precoded, commercially available set of programs that eliminates the need to
write software programs for certain functions...................................................................................................33
Spreadsheets...................................................................................................................................................36
Data Management Software..........................................................................................................................37
Presentation Graphics...................................................................................................................................38
Integrated Software Packages and Software Suites......................................................................................38
Chapter Four: Data Processing..............................................................................................................................41
Data Processing..................................................................................................................................................41
Hardcopy............................................................................................................................................................41
Softcopy.............................................................................................................................................................41
Data processing Cycle/System...........................................................................................................................42
Figure 4.0. The data processing cycle................................................................................................................42
The table below shows sample data processing cycle activities........................................................................42
Functions of stages in the data processing cycle...........................................................................................43
Processing Components.....................................................................................................................................43
Output Component.............................................................................................................................................43
Storage Component............................................................................................................................................43
Data Processing Methods...................................................................................................................................43
i. Manual data processing......................................................................................................................................43
Factors That Influence Selection Of Data Processing Method......................................................................44
Manual Data Processing................................................................................................................................44
Mechanical.....................................................................................................................................................45
Characteristics....................................................................................................................................................45
Advantages.........................................................................................................................................................45
Disadvantages....................................................................................................................................................45
Electromechanical Data processing...............................................................................................................45
Advantages.........................................................................................................................................................46
Disadvantages....................................................................................................................................................46
Electronic Data processing Systems..............................................................................................................46
Characteristics....................................................................................................................................................46
2
, Advantages.........................................................................................................................................................46
Disadvantages....................................................................................................................................................46
Why data processing is necessary......................................................................................................................46
Data processing techniques............................................................................................................................47
Batch Processing / Off-Line Processing............................................................................................................47
Characteristics................................................................................................................................................47
Advantages.....................................................................................................................................................47
Disadvantages....................................................................................................................................................47
Application.........................................................................................................................................................48
Time Sharing......................................................................................................................................................49
Characteristics....................................................................................................................................................49
Summary................................................................................................................................................................51
Chapter Five: File design and organization...........................................................................................................52
The data hierarchy..............................................................................................................................................52
Factors to consider in file design...................................................................................................................54
Storage media.........................................................................................................................................................54
Serial files......................................................................................................................................................55
Sequential file................................................................................................................................................55
Indexed sequential.........................................................................................................................................55
Direct access/Random/immediate access......................................................................................................56
Applications of file design/organisations sequential.....................................................................................56
Application.............................................................................................................................................................57
Merits.....................................................................................................................................................................57
Demerits.................................................................................................................................................................57
Application.............................................................................................................................................................57
Application.............................................................................................................................................................57
Chapter Six: Information systems used in Organisations......................................................................................58
Major Types of Systems in Organizations.........................................................................................................58
MIS summarize and report on the company’s basic operations. The basic transaction data from TPS are
compressed and are usually presented in long reports that are produced on a regular schedule. The following
figure shows how a typical MIS transforms transaction level data from inventory, production, and accounting
into MIS files that are used to provide managers with reports. The figure below shows a sample report from this
system....................................................................................................................................................................63
Chapter Seven: Communication Networks............................................................................................................69
Network: A network is basically two or more computers connected through a cable or wire or space which
share resources. Network software controls how the computers communicate....................................................69
Components and Functions of a Telecommunications System.........................................................................69
Types of Signals: Analog and Digital............................................................................................................71
Data transmission modes between devices........................................................................................................72
There are three ways by which data signals can be relayed between communicating devices. These ways are:. 72
Simplex transmission.............................................................................................................................................72
Half duplex transmission.......................................................................................................................................72
Full duplex transmission........................................................................................................................................72
Simplex transmission.....................................................................................................................................72
Half-Duplex...................................................................................................................................................72
Full Duplex....................................................................................................................................................72
Scope of Networks.............................................................................................................................................73
Local Area Network.......................................................................................................................................73
Wide Area Network.......................................................................................................................................73
Basic Connectivity Components........................................................................................................................74
3
, a) Network Adapters..............................................................................................................................................74
b) Network Cables..................................................................................................................................................75
i. Twisted-Pair Cable.............................................................................................................................................75
ii. Coaxial Cable....................................................................................................................................................75
Coaxial cable consists of a copper wire core surrounded by insulation, a braided metal shielding, and an outer
cover. The core of a coaxial cable carries the electronic signals that make up the data. This wire core can be
either solid or stranded. There are two types of coaxial cable: ThinNet coaxial cable (10Base2) and ThickNet
coaxial cable (10Base5). Coaxial cabling is a good choice when transmitting data over long distances and for
reliably supporting higher data rates when using less sophisticated equipment....................................................75
iii. Fiber-Optic Cable.............................................................................................................................................76
Fiber-optic cable uses optical fibers to carry digital data signals in the form of modulated pulses of light.
Because fiber-optic cable carries no electrical impulses, the signal cannot be tapped and its data cannot be
stolen. Fiber-optic cable is good for very high-speed, high-capacity data transmission because the signal is
transmitted very quickly and with very little interference.....................................................................................76
Selecting Cables.................................................................................................................................................76
Wireless Communication Devices.....................................................................................................................76
i. Infrared Transmission.........................................................................................................................................77
ii. Narrowband Radio Transmission......................................................................................................................77
Network Topologies...........................................................................................................................................77
i. Bus Topology......................................................................................................................................................78
ii. Star Topology.....................................................................................................................................................78
iii. Ring Topology...................................................................................................................................................78
iv. Mesh Topology..................................................................................................................................................79
v. Hybrid Topologies.............................................................................................................................................80
a) Star-Bus.............................................................................................................................................................80
b) Star-Ring............................................................................................................................................................80
Types of Data Transmissions.................................................................................................................................81
Unicast...................................................................................................................................................................81
Broadcast................................................................................................................................................................81
Multicast................................................................................................................................................................81
Chapter Eight: The Internet...................................................................................................................................83
What Is the Internet?.........................................................................................................................................83
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