DEFINITION:
"An operating system is a set of system software programs in a computer that regulate the ways application software programs use the computer hardware and ways that user control the computer."
Cellular OS is the operating system that
operates a smartphone, tablet, PDA, or other digital mobile devices. Modern
mobile operating systems combine the features of a personal computer operating
system with touchscreen, cellular, Bluetooth, WiFi, GPS mobile navigation,
camera, video camera, voice recorder,music player, Near field communication,
and other features.
ERA:
Operating
system was absent in the first commercial form of electronic computer launched
in 1940's.The earliest version of operating system was used by the General
Motors Research Laboratories. IBM 701 was the first operating system equipped
computer architecture.This type of computer system was known as batch
processing system. Through the 1950s, many major features were pioneered in the
field of operating systems and after that many Os's were launched by IBM for
mainframe computers. During 1970's according to need of companies and
organizations many OS were introduced like General Comprehensive Operating
System (GCOS), DOS, Apple Macintosh computer with an innovative Graphical User
Interface (GUI), Linux, etc.
However these days many advance OS are
available such as.....OS x Mountain lion(Mac), Leopard, windows 8, windows 7,
windows server 2012, Android 4.1, etc.
Common Features of OS:
Program Execution Providing Interfaces Handling Input / Output Operations Error Handling Memory management Process management.- Now the reason behind the advancement is to manage critical resources in increasingly complex computer Architecture. The performance issues incurred by the increasingly complex structure and operations of these resources have not been effectively addressed at any level of computer systems.The overall performance of a computer system is increasingly hindered by data accesses to memory and storage.Thus, acquiring good performance more and more relies on fast data accesses by making efficient use of the resources on memory hierarchies. This dissertation advances operating systems and database systems to manage the shared resources to support fast data accesses for applications running on multi-core platforms.
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1) Single-user
operating systems
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a a) Graphical User Interface or GUIs
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b b) Command Line Interface (CLI) operating systems
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2) Multi-user
operating systems
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3) Multi-processor
and multi-tasking operating systems
FUNCTION OF OS
Access Control
When a computer is started, it runs
in the supervisor mode, by which we mean that the first few programs running on
the computer and the operating system have an unlimited access to the hardware.
An operating system has the ability to place the computer in the protected
mode, wherein programs are given a limited access to computer resources.
Execution of Programs
Programs in execution are known as
processes. The execution of a program requires the operating system to create
processes. The operating system kernel creates a process by loading program
code from the disk and allocating memory to it before running the program.
User Interface
Users interact with operating systems
by means of command line interfaces or graphical user interfaces. Though
graphical user interface cannot be referred to as an operating system service,
many operating systems integrate support for user interfaces into their
kernels. Beginning from Windows 95, Microsoft Windows has kept revising its
user interfaces. Their latest operating system, Windows Vista implements a
graphics subsystem.
Memory Management
The operating system kernel handles
the allocation and management of memory that programs use. In a cooperative
memory management strategy, it is assumed that programs make a voluntary use of
the computer memory. This strategy was used by operating systems of old times.
Modern operating systems implement segmentation and paging mechanisms
facilitating memory protection, whereby all the computer programs can obtain a
fair share of memory for execution. The operating system kernel controls the
amount of memory allocated to application programs. An operating system can use
the same memory locations for multiple tasks, using the underlying concept of
virtual memory and swapping or paging.
Scheduling
An operating system kernel consists
of a scheduler program that manages the time taken by each program for its
execution. Kernel passes the controls to processes whereby the
processes can access the CPU and memory. In cooperative multitasking, each
process is allowed to use the system resources for an unlimited period of time.
Pre-emptive multitasking mechanisms have replaced cooperative multitasking.
Windows NT was the first to implement pre-emptive multitasking. This feature
reached the users after Windows XP was released.
Interrupt Handling
An operating system has to deal with
unexpected events in program execution. They are known as interrupts.
Interrupts may also come from computer hardware. If a piece of computer
hardware triggers an interrupt, the operating system kernel devises ways to
handle it. Interrupts triggered by running programs can also be handled by the
operating system kernel.
Management of Files
Operating systems are in charge of
handling the application program access to files stored on the disk. The
operating systems in earlier days did not support different types of file
systems. But the relatively recent operating systems, like Unix and Linux, implement a virtual file system allowing
various types of programs, to access a wide variety of system resources and
devices that use different file systems.
File systems
File systems are methods used for storing and managing
computer files and data. A file system can be considered as a specialized
storage system for the organization, access and retrieval of data. To get a
glimpse of some file systems like FAT and NTFS, go
through FAT and NTFS Data Recovery Information.
Computer Security
I am sure you are aware of multiple
user profiles on operating systems. When you login to your user account on the
operating system you use, you are actually being a part of the security
measures implemented by your operating system. Most of the operating systems
require its users to login to their accounts by means of a username and
password. Recent developments in technology have introduced biometry to
operating systems. Windows Vista has introduced User account control, whereby
each logon session is associated with a token containing the privilege assigned
to that session.
Computer Networking
Operating systems support a variety of
networking protocols,
whereby, computers running different operating systems can work over a common
network. The operating system support for networking protocols enables the
computers to access resources on remote computers in fairly simple ways.
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| POPULAR OPERATING SYSTEMS |
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