Introduction of operating system
An operating system is the collection of the system software
which helps to manage the computer resources and also acts as an interface
between user and computer hardware. The computer resources ma be I/O devices, memory,
processor, storage, data instructions, programs etc.
It helps to make platform for the execution of application
software as well as other different software, such as utilities, system
utilities, language translator etc. without operating system we cannot operate
computer. Its just like a dull machine.
Hence operating system is the link between computer hardware
and user.
Examples: MS-DOS, RC-DOS, Unix: CUI based OS
MS-
Windows, MAC-OS, LINUX, Sun Solaris: GUI based OS
Organization of OS
INTERFACE OF OS
Introduction of Interface
An interface is a platform between computer hardware and
user. It defines means of communication between computer and user. Moreover it
also provides space for the execution of the application software. On the other
hand an interface is also known as the common rules between computer and user.
That mans how computer is operated by using user. Mainly there are two types of
the interface or operating system on the basis of the user interface:
CUI (Command line user interface)
In CUI
based operating system, user can interact between computer by using character
based commands. User should know almost all the command to interact with the computer.
it is difficult to remember all the commands to the normal user so it is also
taken as less user friendly. It is not so much popular in the computer world
like GUI. But, CUI also has an advantage that it can take very less amount of
the memory and it executes faster.
As for example: DIR command is used to view all files
directions in specific locations. form the same purpose in UNIX or Linux we can
use LS command
Examples: UNIX, MS- DOS, PC-DOS etc.
GUI (Graphic user interface)
In CUI based
operating system, user can interact with the computer by using the graphical
components like icons, menu, toolbar, textbox, scrollbar, desktop, window etc.
User can
excess these graphical components by using pointing device. Moreover it also
provides features just like click, double click, minimize, maximize, restore,
close, drag and drop etc. GUI based operating system is more user friendly
because it is very easy to use such type of operating system. so, it is also
more popular than CUI based operating system.
We had a
wide variation of the application software called GUI environment. It has an
disadvantage that GUI based operating system requires more memory so it
executes slower than that of the CUI.
FUNCTIONS OF OPERATING SYSTEM
The factions of the operating systems are discussed below:
1. Process management
2.
I/O
management
3.
memory
management
4.
storage
management
5. Virtual memory management
6.
File
and directory
7.
Back
up and recovery
8.
Security
9.
command
interpretation
10.
Interrupt
handling
11.
Scheduling
12.
Spooling
and buffering
Their descriptions are given bellow:
1. Process management
The part of the program which is currently locating in the
operating system. there are three states of processing they are:
Ø Ready
state: ready to process
Ø Running
state: processing
Ø
Blocking state
Well there are other two states also but they don’t have so
much value like above the those remaining are:
Ø
end
state: not processing
Ø
waiting
state: waiting for processing
2.
I/O
management
The problem with input and output is that different I/O
device has different characteristics, and run at different speeds. The I/O
devices are very slow devices and the co-ordination of it between computer and
I/O is called spooling. It is used for the management of the I/O devices. it is
a traditional approach. This technique uses hard disk hence it is slower.
Where as
buffering is a technique to manage the buffer area inside ram which contains
currently incoming and outgoing data it
executes faster and it is also known as the modern technique.
3.
memory
management
Most computers nowadays are capable of holding several
programs in the memory simultaneously so that a user can switch from one
application to another. in order to execute any instructions and programs it
requires certain space which is managed by the operating system and this
management is called the memory management. Its main work is allocation and de-allocation
of memory.
4.
storage
management
it helps to provide space or manage the area in the storage
devices for storing the application for the future reference.
It acts like, as if it helped for backup and
recovery.
5. Virtual memory management
Virtual memory is a technique for making a computer appears
to have more memory than it actually has. by holding process in a special area
on disk and only loading small portions of a processes and when they are needed,
swapping them out which is in the turn of the next process to have processor
time, many process can effectively share the same memory space.
RAM executes
the programs more than its size so it uses hard disk and the process of using
hard disk when required by the process of paging and swapping is called virtual
memory there are two terms in the virtual memory they are:
Ø
Paging:
It is the process of slicing the big programs in small swamps.
Ø
Swapping:
it is the process of interchanging the pages from RAM to hard disk and vice
versa called swapping.
6.
File
and directory management
A table is used for the management of the files which is
called the file management.
|
ID
|
Name
|
Ext
|
Date
|
Location
|
|
|
|
|
|
|
It
helps for allocating the space in the storage devices to hold stored and to
de-allocate space is usually divided into fixed sized locations units of say
510 or 1024 bytes. it also helped for making the C, D, E, F, G, drivers
7.
Backup
and recovery
An operating system helps for keeping the back up and
recovery. Permanently stored data in the computer for the future reference is
called back up. If sometime while using the application if it gets ceased by
the virus or any thing it helps to re install the application by keeping the
folder of the application permanently in the computer in a specific area.
Thus we can
say that operating system helps for the backup and recovery.
8.
Security
management
When a computer contains the number of items of software,
accessing various stores of information, this must be protected from each
other.
Protection
is generally files or applications of same size or same name should be separated.
And this separation is also done by the operating system. While installing the
operating system some of the free anti virus application are also installed,
which helps to protect the computer from the viruses and other important thing
is that, it helps to put password for the safety of the computer or for the
miss use of the computer by an unknown user.
9.
command
interpretation
The special program inside the operating system which helps
for converging or we can say that which helps for making the computer easier to
use to those who have the habit to use the cui based operating system. It is just
a program which helps to understand the commands for using the compute.
10.
Interrupt
handling
Interrupt handling is the exceptional process during sifting
from one job to another. There are two types of the interruption they are:
Ø
Hardware
level interruption: the interruption in the hardware is called hardware level
interruption. For example: alt+ctrl+del
Ø
Software
level interruption: the interruption in the software is called software level
interruption
11.
Scheduling
The job management routine of the operating system is called
scheduling. It helps for management of the jobs and it also does the job scheduling
as per the user suggestion and then the computer starts to schedule the jobs as
per the priority of the job. the job which is more important it is in the first
list and those jobs which are not so much important they are schedules at last
for the processing.
12.
Spooling
and buffering
The operating system does the process of spooling and buffering.
their descriptions are:
Ø Spooling:
The I/O devices are very slow devices and the co-ordination of it between
computer and I/O is called spooling. It is used for the management of the I/O
devices. it is a traditional approach. This technique uses hard disk hence it
is slower.
Ø Buffering: Where as buffering is a technique
to manage the buffer area inside ram which contains currently incoming and
outgoing data it executes faster and it
is also known as the modern technique
Types of operating system
We can categories the operating system in two different
categories they are:
Ø On the basis of the operational mode
Ø On the basis of user
Their descriptions are:
v On the basis of the operational mode
On the basis of the operational mode we can classify the
operating system into 6 types they are:
1. Batch processing operating system:
In early days, data and respective
programs were composed in a single unit called batch. in other words it is
defined as the group of data and program stored in magnetic tape in sequential
order.
2. Multiprogramming /multitasking OS
Context switching is the process of processing or loading a
program on RAM at a time and again exchange after finishing in the fractions of
seconds or neon seconds.
Example: system 360
3.
Time
sharing OS
Processor makes the slice of its time because it is extremely
faster and it gives the time for processing as per its size and speed. So while
processing many jobs, it helps for the time scheduling. It also has the
priority list. it does the multi job processing.
Example: UNIX
4.
Real
time OS
The system in which the processor job is predefined and its
processing time is very limited.
So it is used in IT scanner, defense system etc. it is said
that it gives the output immediately. it makes us fell that no time is required
for processing.
5.
Multi
processing OS
The operating system in which the multiple processor does
the multi processing task in fraction of seconds is called multi processing. It
helps us for doing the multiple job in the computer. This type of OS helps for
the multiple job processing at a time in a computer with a great efficiency.
6.
Network
and distributed OS
The operating system that helps for the network processing or
processing the data from the server of the far distance server is called
network connection or the local area connection. it helps to see and edit the
documents of the server or in other words we can say that it helps for using
the storage of viewing the storages of the server or a certain place.
v On the basis of user
1. SINGLE USER OS
DOS is the best
example of the single user. If a system can execute single program in computer
system at a tine then it is called single user operating system
User may be
program or person.
2.
MULTI
USER OS
If a system can simultaneously execute more than one program
at a time then such operating system is called as multi user operating system.
Examples: UNIX,
Linux, MAC-OS etc
INTROSUCTION TO DOS
DOS is a short
form of disk operating system. DOS is the operating system developed for the
disk drivers. In the other words the operating system which on disks is known
as disk operating system.
For running smoothly the older version of word perfect, Dbase, LOTUS
1-2-3, and even window 3.1we need DOS as a platform or back ground for handling
tasks.
Features of DOS
ü MS-DOS
supports various computer languages.
ü It
is a single user based operating system.
ü It
supports both floppy disk and hard disk drivers.
ü MS-DOS
manages files in presence of order.
ü MS-DOS
allows flexible file allocation.
ü MS-DOS
supports pipes 2 and I/O redirection.
ü MS-DOS
can consist with each other operating systems.
Advantages of DOS
1. it
helps to support the various computer languages.
2. it
is easier to give interact by the help of
DOS
3. It
also helps supports both floppy disk and hard disk drivers.
4. MS-DOS
manages files in presence of order which helps us for managing the computer.
5. MS-DOS
allows flexible file allocation which helps for the easy identification of the
file when needed.
6. MS-DOS
supports pipes 2 and I/O redirection which helps to have more user friendly.
7. MS-DOS
can consist with each other operating systems that help for the globalization.
Internal commands
External commands
Introduction to windows
Microsoft Windows is
a family of proprietary operating systems most
commonly used on personal computers. It is the most common family of operating
systems for the personal computer, with about 90% of the market share.[6][7][8] Currently,
the most widely used version of the Windows family is Windows XP[9],
released on October 25, 2001. The newest version is Windows 7 for
personal computers and Windows Server 2008 R2 for servers.
Features of windows
ü It
is GUI based operating system
ü Here
we can use graphical components.
ü It
helps to interact with the computer with out giving commands.
ü It
supports all the I/O devices.
ü It
supports multi user and network data processing.
Advantages / disadvantage of windows
ü It
is easier to give inpit and thake output in the windows.
ü We
can use graphical components for interacting with the computer.
SUMMARY
v Market summary:
As we talk in the global market the 90% of the computer operating system
is captured by the windows and rest of there parts are occupied by the
operating systems like LINUX, Unix, sun Solaris
1market summary
Introduction to Linux/ UNIX
Ken Thompson wrote B, mainly based on BCPL, which he used to
write UNIX, based on his experience in the MULTICS project.
B was replaced by C, and UNIX developed into a large, complex
family of inter-related operating systems which have been influential in every
modern operating system. The Unix-like family
is a diverse group of operating systems, with several major sub-categories
including System V, BSD, and GNU/Linux.
The name "UNIX"
is a trademark of The Open Group which licenses it for use
with any operating system that has been shown to conform to their definitions.
"Unix-like" is commonly used to refer to the large set of operating
systems which resemble the original UNIX.
Advantages / disadvantages
ü
Unix-like systems run
on a wide variety of machine architectures.
ü
They are used heavily
for servers in business, as well as workstations in
academic and engineering environments
ü
Some Unix variants
like HP's HP-UX and
IBM's AIX are designed to run only on that
vendor's hardware
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