2. Computer software
Organized information in the form of operating
systems, utilities, programs, and applications that
enable computers to work.
Software consists of carefully-organized instructions
and code written by programmers in any of various
special computer languages. Software is divided
commonly into two main categories
(i)Application software
(ii) System software
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3. Computer software
Systems software
Set of programs that coordinates activities and functions of the
hardware and various other programs
Application software
Programs that help users solve particular computing problems
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4. Application software
Application software is a program or
group of programs designed for end
users.
Application software can also be stored on
CDs, DVDs, and flash or keychain storage
devices
In most cases, application software resides on
the computer’s hard disk
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5. Application Software
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Primary function is to apply the power of the
computer to give individuals, workgroups, and the
entire enterprise the ability to solve problems and
perform specific tasks
Application programs interact with systems
software; systems software then directs computer
hardware to perform the necessary tasks
6. Overview of Application Software
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Proprietary software: one-of-a-kind program for
a specific application, usually developed and owned
by a single company
Off-the-shelf software: existing software program
that is purchased
8. Overview of Application Software
(continued)
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A Comparison of Proprietary and Off-the-Shelf Software
9. Overview of Application Software
(continued)
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A Comparison of Proprietary and Off-the-Shelf Software (continued)
10. Personal Application Software
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Serves the needs of an individual user
Includes personal productivity software
Enables users to improve their personal effectiveness
13. Personal Application Software (continued)
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Software suite: collection of single application
programs packaged in a bundle
Microsoft Office: most popular general-purpose software suite
Other general-purpose software suites: Corel’s WordPerfect
Office, Lotus SmartSuite, Sun Microsystems’s StarOffice
Integrated application packages: offer a range
of capabilities for less money than software suites
Example: Microsoft Works
15. Workgroup Application Software
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Workgroup application software: support
teamwork, whether people are in the same
location or dispersed around the world
Groupware: software that helps groups of
people work together more efficiently and
effectively
17. Enterprise Application Software
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Software that benefits an entire organization
Enterprise resource planning (ERP)
software: set of integrated programs that manage a
company’s vital business operations for an entire
multisite, global organization
19. Role of Systems Software
System software…
Is an interface or buffer between application software and
hardware
Controls the computer hardware and acts as an interface with
applications programs
Schematic
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21. Operating System Functions
Perform common computer hardware functions
Provide a user interface
Provide a degree of hardware independence
Manage system memory
Manage processing tasks
Provide networking capability
Control access to system resources
Manage files
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22. User Interface
User interface
A function of the operating system that allows individuals to
access and command the computer
Command-based user interface
A particular user interface that requires text commands be given
to the computer to perform basic activities
E.g., unix, DOS
Graphical user interface (GUI)
A user interface that uses pictures (icons) and menus displayed on
the screen to send commands to the computer system
E.g. Windows, MAC OS
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23. Systems Software Concepts
Hardware independence
Operating system (OS) provides hardware independence for
application software
Application software interfaces with the operating system
which interfaces with the hardware
When the hardware is changed, the operating system is
changed so that the application software is not required to be
changed
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28. Virtual Memory & Paging
Virtual memory
Memory that allocates space in secondary storage to
supplement the immediate, functional memory capacity of
RAM
Paging
A function of virtual memory allowing the computer to store
currently needed pages in RAM while the rest of the pages wait in
secondary storage
Schematic
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29. Programs
and other
software
Program 1 (a few pages)
Program 2 (a few pages)
Program 3 (a few pages)
Program 4 (a few pages)
Program 5 (a few pages)
Program 6 (a few pages)
Other memory requirements
Operating
system and
system
software
Memory Disk
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30. Virtual Memory ‘Discussion’ (1)
An imaginary memory area supported by some operating
systems (for example, Windows but not DOS) in conjunction
with the hardware.
You can think of virtual memory as an alternate set of
memory addresses.
Programs use these virtual addresses rather than real
addresses to store instructions and data.
When the program is actually executed, the virtual addresses
are converted into real memory addresses.
The purpose of virtual memory is to enlarge the address
space, the set of addresses a program can utilize.
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32. Multitasking, Multithreading, Time-sharing
Multitasking
A processing activity that allows a user to run more than
one application at the same time
Multithreading
A processing activity that is basically multitasking within
a single application
Time-sharing
A processing activity that allows more than one person to
use a computer system at the same time
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