UNIX/LINUX
Software:
Software is a collection of computer
programs and related data that
provide the instructions for telling a computer what to do and how to do it.
Software is divided into two types.
1. System
S/W:
System S/W is a combination of device drivers and operating
system.
2. Application
S/W:
Application software, also known as an application or an
"app", is computer software designed to help the user to perform specific
tasks. Application S/W communicates with hardware components trough
System S/W.
Application
Software
|
System
Software
|
Hardware
Components
|
Device drivers:
It is a hardware program used to communicate with hardware devices.
Every device in system will
have its own device driver.
v Operating
System Overview:
An operating system (O/S) is a set of
programs that manage computer Hardware resources and provide common services
for application software
.
The operating system is the most important type of System software in a
computer system. A user cannot run an application program on the computer
without an operating system, unless the application program is self booting.
· O/S
is a platform where we can run application S/W (c, c++, java, etc..,)
· O/S
is an interface between Application S/W and Hardware Components
· O/S
provides an environment to run applications. That environment is called “child
process”. O/S is called parent of all current running applications.
OS is divided into two
types of interfaces
1. CUI (Character User
Interface)
Here
Work done by commands. Here you are allowed to work only with keyboard. In CUI
one task runs at a time.
Application: MS Dos
2. GUI (Graphical User
Interface)
Here work done in user friendly environment. Here you are allowed to work
with
any pointing device like mouse. In GUI more tasks can run simultaneously.
Application:
Window
·
History of
Unix/Linux
Before UNIX operating system we have DOS operating
system which is machine dependent and single user O/S. By using this O/S
wastage of much hardware and time consumed to develop any project.
To
overcome the disadvantages of DOS O/S, in 1969 at AT & T Bell labs
software team lead by Dennis Ritche, Ken Thomson, Rudd canady and Brian
Kernighan developed a project called MULTICS (Multiplexed Information
Computing System).
MULTICS was developed to share the resources. It was developed only for two
users. MULTICS was developed in assembly language. In the same year it is
modified to hundreds of users and named as UNICS (Uniplexed information
Computing System).
In
1972 “C” – language was developed, which is most powerful language.
In 1973 UNICS was rewrote in C- language and renamed
as UNIX.
·
Features of UNIX/Linux
·
Multiuser
O/S:
UNIX server supports the multiple users with the
help of process based technology. Process based technology works based on time
sharing between users and queue.
·
Multi-Tasking
O/S
User can perform more than one job at a time. User
can run the task as background process by affixing ‘&’ (ampersand) to
the command and can run one more job as foreground job; foreground will be
given highest priority and next is its background job. So user can run
important job as foreground job.
Advantage of Multi-tasking is to utilize the maximum
CPU time
·
Multiprogramming
Support more than one program, in memory, at a
time. Amounts to multiple user processes on the system.
·
Programming
facility
UNIX provides shell which works like a programming
language. It provides the commands, keywords, control statements and operators
to develop the shell scripting for system administrators, developers and
testers.
·
Open System
UNIX from the beginning is an open source. User can
modify the Unix O/S as per his requirements. User can add new system devices
and update complete Unix O/S
·
Portable O/S
UNIX is an independent of hardware it works with all
processors from 8085 to super computer.
·
Software
Development Tools
UNIX offers an excellent variety of
tools for software development for all phases, from program editing to
maintenance of software.
·
Security
It provides security for local resources like files
and hardware devices
·
Flavors of
UNIX
Many of the proprietary flavors have been
designed to run only (or mainly) on proprietary hardware sold by the same
company that has developed them. Examples include:
·
AIX - developed by IBM for use on its
mainframe computers
·
BSD/OS - a commercial version of BSD developed by
Wind River for Intel processors
·
HP-UX - developed by Hewlett-Packard for its HP
9000 series of business servers
·
IRIX - developed by SGI for applications that
use 3-D visualization and virtual reality
·
QNX - a real time operating system developed
by QNX Software Systems primarily for use in embedded systems
·
Solaris - developed by Sun Microsystems for the SPARC
platform and the most widely used proprietary flavor for web servers
·
Tru64 - developed by Compaq for the Alpha
processor
Others
are developed by groups of volunteers who make them available for free. Among
them are:
- Linux -
the most popular and fastest growing of all the Unix-like operating
systems
- FreeBSD - the most popular of the
BSD systems (all of which are direct descendants of BSD UNIX, which was
developed at the University of California at Berkeley)
- NetBSD - features the ability to
run on more than 50 platforms, ranging from acorn26 to x68k
- OpenBSD - may have already attained
its goal of becoming the most secure of all computer operating systems
- Darwin - the new version of BSD
that serves as the core for the Mac OS X
This
diversity has had both positive and negative effects. Most importantly, it has
resulted in a healthy competition amongst them, which has been a major factor
in the rapid improvement of the Unix-like systems as a whole
·
Comparison
of UNIX with Windows
1. UNIX and Windows
both Multi user O/S.
2. UNIX and Windows
both support multi-tasking.
3. UNIX is process
based technology. Windows is thread based technology.
4. Process based
technology performance is less and it is a heavy weight technology. Thread
based technology is a light weight technology and performance is more.
5. UNIX is independent
of machines. Windows is an Intel Processor Based.
6. UNIX O/S performs
more than Windows with high speed processors in the market.
7. UNIX is an open system;
Windows is a closed system.
8. UNIX provides
system call access whereas windows cannot.
9. UNIX is portable
O/S, windows are not.
10. UNIX provides the programming facility
where as Windows will not.
11. Unlimited users can work with UNIX O/S,
Windows only limited users.
12. UNIX provides security for local resources
whereas Windows will not provide.
13. UNIX is not user friendly. Windows is User
friendly.
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Thank you :
- kareem