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2. o An OS is an interface between user
and hardware of a computer system.
o An OS also called as a Resource
Manager.
o OS is in charge of a system so all the
requests to use the resources need to go
through OS.
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3. o To make the computer system convenient to
use.
o To use the computer hardware in an efficient
manner.
o To provide an environment in which a
user may execute programs.
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4. o Memory management
o Process management
o Device management
o Information management
o Protection
o Error Handling
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5. o Memory management
The o/s keeps track of the
memory, what parts are in use
and by whom.
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6. o Process management
The o/s keeps track of processors
and the status of processes. It
decides who will have a chance
to use the processor.
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7. o Device management
The o/s keeps track of the devices,
channels, control units and decides
what is an efficient way to allocate
the device.
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8. O/S keeps track of the information,
its location, use, status etc. and
decides who gets use of the
resources, enforce protection
requirements
o Information management
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9. An o/s is to protect the user from
unauthorized access of his files or
data. And also it should protect
itself from users
o Protection
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10. An o/s must respond to errors by
taking the appropriate actions.
o Error Handling
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11. STRUCTURE OF AN OPERATING
SYSTEM
Users
Application Programs
Operating System
Computer Hardware
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12. o Hardware - Physical components of a
computer.
o Software – Set of computer programs.
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13. System Programs Application Programs
oo Which manages
Which manages oo Which solve
Which solve
the operations of
the operations of problems for
problems for
the computer
the computer their users
their users
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14.  First generation: 1945 – 1955
◦ Vacuum tubes
◦ Plug boards
 Second generation: 1955 – 1965
◦ Transistors
◦ Batch systems
 Third generation: 1965 – 1980
◦ Integrated circuits
◦ Multiprogramming
 Fourth generation: 1980 – present
◦ Large scale integration
◦ Personal computers
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15.  Batch Operating System
 Time-Sharing Operating System
 Real-Time Operating System
 Multiprogramming Operating System
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16.  Batch Operating System
Batch operating system is the one which
analyzes our input and groups them into
batches .That is data in each batch is of
similar characteristics. And then it performs
operation on each individual batch.
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17. Computer provides computing services to several or
many users concurrently on-line. Various users are
sharing the central processor, the memory and
other resources of the computer system. The user
has full interaction with the program during its
execution.
 Time-Sharing Operating System
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18. A real-time operating system aims at executing real-
time applications. The main objective of real-time
operating system is their quick and predictable
response to events. Such systems often use
specialized scheduling algorithms so that they can
achieve a deterministic nature of behavior.
 Real-Time Operating System
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19. A multiprogramming operating system is a system
that allows more than one active user program to be
stored in main memory simultaneously. Time-
sharing systems are multiprogramming systems.
More than one job is “ready” at the same time.
 Multiprogramming Operating System
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20. Operating System can also be classified
as follows –
 Single User Systems
 Multi User Systems
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21.  Provides a platform for only one user at a time.
 Theyare popularly associated with Desktop
operating system which run on standalone systems
where no user accounts are required.
 Example: DOS
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22.  Refers to computer systems that support two or
more simultaneous users.
 Another term for multi-user is time sharing.
 Example: Unix
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23.  Microsoft Windows
 Linux
 Unix
 Mac OS X
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24.  Microsoft Windows
 Gamers
 People who must use Windows-only software for
work or school.
 People or businesses looking for an inexpensive
computer yet do not have the ability to use Linux.
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25.  Linux And Unix
 Experienced computer users looking for a good,
free operating system.
 Businesses looking for reliable and affordable
computing, so long as they do not need Windows-
only software and have a competent IT manager.
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26.  Mac OS X
 Home users looking for an easy and reliable
computing experience who are willing to pay more
than low-end PC prices.
 Graphic designers and photographers.
 Scientists.
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27. Though it is not clear which is the best operating system, as
each does have its advantages and disadvantages, and different
people will be best using different ones. Microsoft Windows is a
common operating system and is a reasonable choice for most
people. Mac OS is second-most popular and is an excellent
operating system for those who can purchase a Mac. Linux is a
very good advanced operating system available for free and is
used by experienced users.
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28.  www.wikipedia.com
 Operating System Concepts 6th Edition by
Silberschatz Galvin
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