2. Introduction
Computer software or just software, is a
collection of computer programs and
related data that provides the instructions for
telling a computer what to do and how to do it.
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3. TYPES OF SOFTWARE
There are two types of software:
Systems software: the operating system.
Applications software: the programs we use.
Systems software is the control software that
operates the hardware and allows the
applications to run.
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4. An Operating System (OS) is the
master controller within a computer.
EX: Windows, MacOS, DOS, UNIX, Linux
An operating system interacts with:
◦ All hardware installed in or connected to a
computer system.
◦ All software installed or running from a
storage device on a computer system.
System Software
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5. Structure of Operating System:
Application Programs
System Programs
Software (Operating System)
HARDWARE
6. System Software
Microsoft Windows
◦ Most popular operating system.
◦ Supports a vast array of application
software and peripheral devices.
MacOS
◦ For Macintosh computers.
◦ Proprietary system.
◦ Does not have same functionality and
support for software and peripheral
devices.
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7. Operating Systems
Operating Systems run in
the background without the
users being aware of it.
It controls the inputs,
outputs, interrupts, and
storage of files as
requested by the
applications software.
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8. System Software
Network operating system (NOS)
◦ Manages network resources.
◦ Maintains security.
◦ Tracks user accounts.
◦ Handles communication between
workstations and servers.
Popular network operating systems
Windows NT, Novell Netware, UNIX
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9. System Software
Utilities
Utilities augment functionality of operating
systems. Utilities includes device drivers
and Troubleshooting capabilities.
Utilities provide file management
capabilities such as copying, moving or
renaming a file.
Norton Utilities includes an undelete
function that can recover deleted files.
Symantec and McAfee Virus checkers add
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10. Types of Operating System
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Batch Processing
Multiprogramming
Multi-tasking
Time Sharing
11. Batch Processing:
In Batch processing same type of jobs batch
(BATCH- a set of jobs with similar needs) together
and execute at a time.
The OS was simple, its major task was to transfer
control from one job to the next.
The job was submitted to the computer operator in
form of punch cards. At some later time the output
appeared.
The OS was always resident in memory. (Ref. Fig.
next slide)
Common Input devices were card readers and tape
drives.
12. Batch Processing (Contd…):
Common output devices were line printers, tape
drives, and card punches.
Users did not interact directly with the computer
systems, but he prepared a job (comprising of the
program, the data, & some control information).
Example: Stock Status at the end of day, bill
generation at the end of month cycle, etc.
OS
User
program
area
13. Multiprogramming:
Multiprogramming is a technique to execute number
of programs simultaneously by a single processor.
In Multiprogramming, number of processes reside in
main memory at a time.
The OS picks and begins to executes one of the jobs
in the main memory.
If any I/O wait happened in a process, then CPU
switches from that job to another job.
Hence CPU in not idle at any time.
14. Multiprogramming (Contd…):
OS
Job 1
Job 2
Job 3
Job 4
Job 5
• Figure dipicts the layout of
multiprogramming system.
• The main memory consists of 5
jobs at a time, the CPU executes
one by one.
Advantages:
•Efficient memory utilization
•Throughput increases
•CPU is never idle, so
performance increases.
15. Multi-Tasking :
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A multi-tasking operating system allows more than one
program to be running at a time, from the point of view of
human time scales. A single-tasking system has only one
running program.
16. Time Sharing Systems:
Time sharing, or multitasking, is a logical extension
of multiprogramming.
Multiple jobs are executed by switching the CPU
between them.
In this, the CPU time is shared by different
processes, so it is called as “Time sharing
Systems”.
Time slice is defined by the OS, for sharing CPU
time between processes.
Examples: Multics, Unix, etc.,
17. Application Software
Application Software consists of programs
that tell a computer how to produce
information. Some of the more commonly
used packages are:
Word processing
Electronic spreadsheet
Database
Presentation graphics
18. Word Processing
Word Processing software is used to create and print
documents. A key advantage of word processing
software is that users easily can make changes in
documents.
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19. Electronic Spreadsheets
Electronic spreadsheet software allows the user to
add, subtract, and perform user-defined calculations
on rows and columns of numbers. These numbers
can be changed and the spreadsheet quickly
recalculates the new results.
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20. Database Software
Allows the user to enter, retrieve, and update data in
an organized and efficient manner, with flexible
inquiry and reporting capabilities.
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21. Presentation Graphics
Presentation graphic software allows the user to
create documents called slides to be used in making
the presentations. Using special projection devices,
the slides display as they appear on the computer
screen.
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