Post on 25-Dec-2015
transcript
1GMS-VU : Module 2
Introduction to Information and Communication
Technologies
Module 2Module 2Computer Software Computer Software
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Scope What is software? What are the types of software? How is software created? What are some problems in using software? How do you ensure security of the system
and data? What are future trends in software
development?
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Learning OutcomesBy the end of this lesson, you should be able to:
1. Define the functions of software in a computer system
2. Identify the different types of software3. List different types of operating systems and
application software4. Identify steps in creating software5. Identify problems in using software6. Describe the ways to ensure security of the
system and data7. Identify general trends in software development
4GMS-VU : Module 2
What is software? A computer system is generally composed
of hardware and software. Hardware makes up the physical
components. Software makes up the set of instructions
for the computer. Without software, the computer will not be able to perform the tasks required.
Sometimes software is called a computer program.
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What are the types of software?
There are two sets of instructions that a computer must follow:
System software such as DOS, Windows, Linux, Unix, and Mac OS
Application software such as those used for word processing, spreadsheets, or library management
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System Software An organized collection of system programs which
serve as the interface between the computer hardware and the user application
It manages the hardware resources: Operating System
CPU management to facilitate sharing execution time of processes
Memory management to allocate memory resources dynamically
I/O management to handle reading and writing devices
Compiler/Interpreter Utilities
CPU
Memory
I/O
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Examples of Operating Systems
Disk Operating System (DOS)Microsoft WindowsMac OSLINUXUNIXOther Proprietary OS
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A generic term describing any operating system that is loaded from disk devices
It is not a user friendly OS since users need to memorize commands and issue them by typing line by line, known as command line interface.
Very few end users use DOS nowadays.
Disk Operating Systems (DOS)
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Microsoft Windows A Graphical User Interface (GUI), which was
originally run on DOS (Windows 3.x), that allows multitasking or the ability to run several programs at the same time
Examples: Microsoft Windows 95 Microsoft Windows 98 Microsoft Windows 2000 Microsoft Windows XP
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Application Software A set of instructions designed to perform a
specific task such as word processing, accounting, cataloguing, library management, animation, etc.
The type of the software depends on the application
General purpose office softwareBusiness softwareSpecial purpose and other software
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General Purpose Office Software Word processing: e.g. MS Word Spreadsheets: e.g. MS Excel Database management
systems: e.g. MS Access, SQL Presentation/Graphics: e.g. MS
PowerPoint, Adobe Photoshop Software suite: e.g. MS Office
*MS stands for Microsoft
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Business Software A set of software used for
business application such as software for banking, e-Commerce, etc.
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Special purpose software and other software Desktop publishing software: e.g. MS Publisher Imaging and drawing: e.g. Corel Draw File management: e.g. CDS/ISIS, INMAGIC Library management software: e.g. Athena,
VTLS, INNOPAC, Library Solutions Other Software: e.g. Statistics and
registration software, etc.
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How is software created? Software Development Process
2.0 Software Design
1.0 Software Analysis
3.0 Programming/Coding4.0 Compiling
5.0 Testing and Debugging
6.0 Implementing and maintenance
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1.0 Software Analysis
•To identify problems and user requirements
2.0 Software Design
•To illustrate what the software will do and what output will be generated
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3.0 Programming/Coding
•To create the software by translating specifications and requirements into program instructions
4.0 Compiling
•To translate program instructions into machine language
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5.0 Testing and Debugging
•To examine whether the software is error free and produces the intended results
6.0 Implementing and Maintenance
•To install and operate the software efficiently
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Programming Languages
Programming languages are used to write software. Some of these are: Low level languages
Assembly High level languages
COBOL FORTRAN C++ Pascal Visual Basic
Programming languages for the Internet Perl Java HTML XML
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What are problems in using software?
Programming languages Character sets Malicious Software
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Problems caused by programming languages Programming languages are usually in English. Applications usually use the English language
and the Roman alphabet. Problems arise when the user is non-English
and/or is using non-Roman script.
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Problems caused by different characters sets
Computers use character sets stored in binary codes.
Different scripts use different character sets.
Computers must know which writing system/character set they are dealing with.
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Problems caused by malicious software
Computer Virus Worm Trojan Horse
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A program or a code that gains access without the users’ knowledge and/or perform actions not intended by the user, often damaging data and sometimes the whole system in the process.
Viruses are activated once unknowing users run, open, view or copy the file containing it.
The action that will trigger the virus to deliver its “payload” depends on the type of virus that infected the file.
Computer Virus
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Characteristics of a virus A self-replicating program whose main purpose is
to propagate itself to as many places as possible Self-propagating by modifying another program to
include itself by an act of a user, e.g. opening/ viewing files unknowing that they are infected and/or copying/transferring files from one system to another through diskettes, file transfer, e-mail, the internet and other means…
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Worm
A program that replicates and propagates itself without any action from the user
This differentiates it from a virus that needs user action in order to replicate.
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A Trojan horse contains hidden functions that, while running, may destroy files or create a “back door” allowing an intruder to access the system.
A Trojan horse, unlike a virus, does not spread by itself but can be as destructive, depending on the intentions of the intruder.
Trojan Horse
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How do you ensure security of the system and data? Back-up your system and your data regularly by
using CD-R, CD-RW, diskettes, tapes, or another hard disk.
Use firewalls, encryption and other security measures to protect data, computer systems and networks from intrusion and attacks done through the Internet.
Protect yourself from malicious software: Virus/Worm/Trojan Horse.
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Protect yourself from Protect yourself from viruses, worms and viruses, worms and Trojan horsesTrojan horses Refrain from running any program or opening any
file from untrusted sources. Scan floppy diskettes and CD-ROMs before using. Install a virus shield to automatically check
diskettes and CDs. Get an updated version of a virus scan program. Always check you hard disk for possible infection,
if you are connected to the Internet. Use diskettes only after they have been scanned.
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What are future trends in software development? More user friendly
More customized More Web enabled More flexible/compatible More sophisticated
programming languages functions