OPERATING SYSTEM
Definition:
An operating system is a
group of computer programs that coordinates all the activities among computer
hardware devices. It is the first program loaded into the computer by a boot
program and remains in memory at all times.
An operating system is
system software that manages computer hardware and software resources and
provides common services for computer programs. The operating system is a
component of the system software in a computer system. Application programs
usually require an operating system to function.
An operating system
sometimes abbreviated as ‘OS’ is the program that, after being initially loaded
into the computer by a boot program, manages all the other programs in a
computer. The other programs are called applications or application programs.
The application programs make use of the operating system by making requests
for services through a defined application program interface (API). In
addition, users can interact directly with the operating system through a user
interface such as a command language or a graphical user interface (GUI).
An operating system performs
these services for applications or functions:
·
In multitasking operating system
where multiple programs can be running at the same time, the operating system
determines which applications should run in what order and how much time should
be allowed for each application before giving another application a turn.
·
OS acts as a bridge between the
user and computer.
·
It manages the sharing of internal
memory among multiple applications.
·
It handles input and output to and
from attached hardware devices such as hard disks, printers and dial-up ports.
·
It sends messages to each
application or interactive user (or to a system operator) about the status of operation
and any errors that may have occurred.
·
It can offload the management of
what are called batch jobs (for example, printing) so that the initiating
application is freed from this work.
·
On computers that can provide
parallel processing, an operating system can manage how to divide the program
so that it runs on more than one processor at a time.
The operating system is
the most important program that runs on a computer. Every general-purpose
computer must have an operating system to run other programs and applications.
Operating system perform basic tasks, such as recognizing input from the
keyboard, sending output to the display screen, keeping track of files and
directories on the disk and controlling peripheral devices such as disk and
printers.
For large system, the
operating system has even greater responsibilities and powers. It is like a
traffic cop it makes sure those different programs and users running at the
same time do not interfere with each other. The operating system is also
responsible for security, ensuring that unauthorized users do not access the
system.
Types of file system:
-
File Allocation Table (FAT)
-
New Technology File System (NTFS)
File Allocation Table
(FAT) uses the file allocation table which records, which clusters are used and
unused and where files are located within the clusters.
NTFS is a file system
introduced by Microsoft and it has a number of advantages over the previous
file system, named FAT32 (File Allocation Table).
One major advantage of
NTFS is that it includes features to improve reliability. For example, the new
technology file system includes fault tolerance, which automatically repairs
hard drive errors without tracks hard drive errors. This can help prevent hard
disk failures and makes it possible to recover files if the hard drive does
fail.
NTFS also allows
permissions (such as read, write and execute) to be set for individual
directories and files.
The classification of
Operating Systems:
In
olden days the OS mainly divided in to two types they are
1.
Character User Interface (CUI)
Example: DOS
2.
Graphical User Interface (GUI) Example:
Window
There are so many of OS
are available in present lays. They are classified depending on the work, way
and users:
·
Single
user: Allows only one user to run programs at the
same time.
·
Multi-user:
Allows
two or more users to run programs at the same time. Some operating systems
permit hundreds or even thousands of concurrent users.
·
Multi-processing:
Supports
running a program on more than one CPU.
·
Multi-tasking
: Allows
more than one program to run concurrently.
·
Multi-threading:
Allows
different parts of a single program to run concurrently.
·
Real
time: Responds to input instantly. General purpose
operating systems, such as DOS and UNIX
are not real time.
Operating systems provide
a software platform on top of which other programs, called application
programs, can run. The application programs must be written to run on top of a
particular operating system. Your choice of operating system, therefore,
determines to a great extent the applications you can run. For PCs, the most
popular operating systems are DOS, OS/2 and windows, but others are available
such as Linux.
Single and Multi-tasking:
A single-tasking system
can only run one program at a time, while a multi-tasking operating system
allows more than one program to be running in concurrency. This is achieved by
time-sharing, dividing the available processor time between multiple process
which are each interrupted repeatedly in time-slices by a task scheduling
subsystem of the operating system. Multi-tasking may be characterized in
preemptive and co-operative types. In preemptive multitasking the operating
system slices the CPU time and dedicates a slot to each of the programs. UNIX
likes operating systems, e.g., Solaris, Linux as well as Amiga-OS support
preemptive multitasking. Cooperative multitasking is achieved by relying on
each process to provide time to the other processes in a defined manner. 16-bit
versions of Microsoft Windows used cooperative multi-tasking. 32-bit versions
of both Windows NT and Win9x used preemptive multi-tasking.
Single and Multi-user:
Single-user operating
systems have no facilities to distinguish users, but allow multiple programs to
run in tandem. A multi-user operating system extends the basic concept of
multi-tasking with facilities multiple users and the system permits multiple
users to interact with the system at the same time. Time-sharing operating
systems schedule tasks for efficient use of the system and may also include
accounting software for cost allocation of processor time, mass storage,
printing and other resources to multiple users.
Distributed:
A distributed operating
system manages a group of distinct computers and makes them appear to be a
single computer. The development of networked computers that could be linked
and communicate with each other gave rise to distributed computing. Distributed
computations are carried out on more than one machine. When computers in a
group work in cooperation, they form a distributed system.
Template:
In an OS, distributed and
cloud computing context, templating refers to creating a single virtual machine
image as a guest operating system, then saving it as a tool for multiple
running virtual machines. The technique is used both in virtualization and
cloud computing management and is common
in large server warehouses.
Embedded:
Embedded operating
systems are designed to be used in embedded computer systems. They are designed
to operate on small machines like PDAs with less autonomy. They are able to
operate with a limited number of resources. They are very compact and extremely
efficient by design. Windows CE and Minix-3 are some examples of embedded
operating systems.
Real-time:
A real-time operating
system is an operating system that guarantees to process events or data within
a certain short amount of time. A real time operating system may be single or
multi-tasking, but when multitasking, it uses specialized scheduling algorithms
so that a deterministic nature of behavior is achieved. An event-driven system
switches between tasks based on their priorities or external events while
time-sharing operating systems switch tasks based on clock interrupts.
Library:
A library operating
system is one in which the services that a typical operating system provides,
such as networking are provided in the form of libraries. These libraries are
composed with the application and configuration code to construct uni-kernels
which are specialized, single address space, machine images that can be
deployed to cloud or embedded environments.
Characteristics of OS:
1. Speed:
Even aside from
incompatibilities other issues that many people had with Vista, one of the most
straightforward was speed – it just felt too sluggish compared to XP, even on
pumped up hardware. Windows7 brings a more responsive and sprightly feel and
Microsoft has spent a lot of time and effort getting the Start Menu response
just right.
Microsoft has also
recognized the need for improved desktop responsiveness, which gives the
impression that the computer is responding to the user and that they are in
control – something that was often lacking with Vista. You can also expect
faster boot times. And the boot sequence is now not only prettier than it was
with Vista, but it’s speedier too.
2. Compatibility:
In
simple terms, compatibility on Windows 7 will be far better than it was with
Vista/ many programs that individuals and companies used on Windows XP did not
work immediately and required updates, but with Windows 7 almost all
applications that work on Vista should still run. In essence, Windows Vista has
done most of the hard work for Windows 7 in this respect.
3. Lower hardware requirements:
Vista gained a
reputation for making even the beefiest hardware look rather ordinary. Windows
7, however will run well on lower end hardware, making the transition from
Window XP less painful.
Microsoft is even
pushing Windows 7 for net books. This could provide a modern replacement for
Windows XP, which has found new lease of life as the OS of choice on net books,
supplanting Linux. The downside is that Windows 7 Starter Edition, as it will
be called, will be limited to only three applications running at the same time.
4. Search and Organization:
One of the best things
about Windows 7 is the improved search tool, which now rivals Mac OS X’s
Spotlight to be able to find what you need quickly and easily. For example,
typing ‘mouse’ will bring up the mouse option within the control panel or
typing a word will display it and split it up nearly into files, folders and
applications.
Also introduced is the
concept of Libraries, which takes the ‘My Documents’ concept a stage further.
The various Libraries, such as Documents and pictures, will match multiple
locations which you can add yourself, so you don’t have to keep everything in
one place.
5. Taskbar/Start Menu:
At first glance, the task bar looks like
nothing has much has changed since Vista. In fact, that’s not the case and it’s
a lot more powerful. Microsoft is now making best use of its aero technology.
By default taskbar icons are now larger and items are grouped together and are
not labeled with clumsy text.
DOS (DISK OPERATING
SYSTEM)
In July 1980 IBM assigned
Microsoft to develop a 16-bit operating system for the personal computer for
the fee of $186,000.
Although the company Digital Research of Gary Kildall already had with CP/M 86
such a 16-bit version, but by circumstances no contact has been established
with IBM Microsoft could not sell licenses, a corresponding agreement with the
company Seattle Computer Products was reached for QDOS. QDOS is a 16-bit clone
of CP/M and was finished by Tim Paterson in April 1980. At first Microsoft
licensed QDOS for $25,000.
After a license agreement with IBM was signed, Bill Gates bought QDOS for $50,000
in July 1981. How proved this was a very lucrative business. IBM delivered it
on all IBM computers as PC DOS for the first time on the IBM 5150 PC, for all
other ones the name MS-DOS was for OEM partner. MS DOS 1.0 consists of about
4,000 lines assembled code.
The command interpreter
is integrated in the file command.com with the internal commands for MS-DOS.
Together with the file IO.Sys for simple device routines like the access to the
monitor, keyboard, fixed storage disks and interfaces as well as the booting
code these from the base operating system. DOS works very hardware near.
Update:
Short for Microsoft Disk
Operating System, MS-DOS is a non-graphical command line operating system
derived from 86-DOS that was created for IBM compatible computers. MS-DOS
originally written by Tim Paterson ad introduced by Microsoft in August 1981
and was last updated in 1994 when MS-DOS 6.22 was released. MS-DOS allows the
user to navigate, open and otherwise manipulate files on their computer from a
command line instead of a GUI like Windows.
MS-DOS has only a minor
roll. It is installed for compatibility reasons for MS-DOS programs and makes.
Windows 95 up to ME start able. DOS programs being executed in the DOS box or
directly in MS-DOS before Windows start. Today it finds application for boot
disks or similar purposes.
In 1988 was MS-DOS established and had reached
measured on the market share a monopoly in the DOS market. The number of the
MS-DOS installations grew worldwide to about 60 million and surpassed all other
systems with that amount. Almost every software company offered standard
applications like word processing, calculation or also special solutions like
measurement tools. CAD (Computer Aided Design) or image processing for MS-DOS.
The PC manufacturers designed her systems compatible to MS-DOS except for few
manufacturers.
MS-DOS 5.0 allows the use
of the High Memory and Upper Memory area for DOS itself, TSR programs and
drivers. The most important new external commands in this version are DOSKEY,
DOSSHELL, EDIT, EMM386 and LOADHIGH. UNDELETE can recover deleted files,
UNFORMAT can undo the format of floppy disks. 2.88 MB floppy disk drives from
IBM are now supported. The BAIC interpreter was improved in detail.
MS-DOS is command oriented
OS. The DOS commands are divided into two types they are:
·
Internal
Commands
·
External
Commands
Internal
Commands:
Commands which the files
are included in the OS itself are called as ‘Internal Commands’. Internal
Commands are basically divided into Directory and File Commands.
Directory
Commands:
Directory commands are used to retrieve the
directories
1. Dir:
This command used for viewing the files and directories
of computer.
Syntax: C:\ Dir ¿(Enter Key)
2. MD
(Make Directory)
This command is used to create new directory
Syntax: C:\> MD <Directory Name> ¿(Enter
Key)
Example: C:\> MD Sree Rama ¿(Enter Key)
3. CD
(Change Directory)
This command is used to move one directory to
another directory
Syntax: C:\> CD <Directory Name> ¿(Enter
Key)
Example: C:\> CD Sree Rama ¿(Enter Key)
C: Sree
Rama>_
4. RD
(Remove Directory)
This command are used to remove directories
Syntax: C:\> RD <Directory Name> ¿(Enter
Key)
Example: C:\> RD Sree Rama ¿(Enter Key)
Note:
This command is used when the directory is empty
only.
File
Commands
These commands are used to create and retrieve
files.
5. Copy
con
This commands are used to create new file.
Syntax: C:\> Copy con <File Name> ¿(Enter
Key)
Example: C:\> Copy con Rose ¿(Enter Key)
6. Cls
(Clear Screen)
This
command is used to the display on the screen. When this command is used at
c-prompt total data cleared on screen.
Syntax: C:\> Cls ¿(Enter Key)
Example: C:\>
7. Copy
This
command is used to make a copy of a file with another name.
Syntax: C:\> Copy <Old File Name><New
File Name> ¿(Enter Key)
Example: C:\> Copy Rose Jasmine ¿(Enter Key)
8. Del
(Delete)
This command is used to delete file.
Syntax: C:\> Del <File Name> ¿(Enter Key)
Example: C:\> Del Rose ¿(Enter Key)
9. Erase
(Delete)
This command is used to delete file.
Syntax: C:\> Erase <File Name> ¿(Enter
Key)
Example: C:\> Erase Jasmine ¿(Enter Key)
10. Edit
This command is used to make a changes of an
existing file.
Syntax: C:\> Edit <File Name> ¿(Enter
Key)
Example: C:\> Edit Rose ¿(Enter Key)
External
Commands
External commands are corresponding commands.
These are gathering commands on out sides.
1. Print
This command is used to print a file.
Syntax: C:\> Print <File Name> ¿(Enter
Key)
Example: C:\> Print Rose ¿(Enter Key)
2. Format
This command is used to format a drive
Syntax: C:\> Format <Drive Name> ¿(Enter
Key)
Example: C:\> Format E: ¿(Enter Key)
Note: New
hard disks or floppies cannot be used directly. They should be formatted first.
When a floppy or hard disk is formatted, the computer makes the available space
for use. When disk is formatted all the
files and directories deleted.
3. Move
This command is used to move File or Directory one
place to another place.
Syntax: C:\> Move <Source> <Target>
¿(Enter Key)
Example: C:\> Move Rose D:\ Sree Rama\ ¿(Enter
Key)
4. CHDSK
(check disk)
This command is used to check a drive or disk for
errors.
Syntax: C:\> CHDSK <Drive Name> ¿(Enter
Key)
Example: C:\> CHDSK A: ¿(Enter Key)
5. Deltree
This command is used to delete a directory along
with all files and directories.
Syntax: C:\> Deltree <Directory Name>
¿(Enter Key)
Example: C:\> Deltree Sree Rama ¿(Enter Key)
Wildcards
These are used in
commands to reduce typing work or command has executed on several files. There
are mainly two wildcard in MS-DOS. They are “*” (Asterisk) and “?” (Question
Mark).
Asterisk is use to substitute of file name or
extension.
The question mark are used as a substitute for a
single character in the file name or extension.
WINDOW OPERATING SYSTEM
Windows operating system is developed by Microsoft
Corporation to run personal computers (PCs). Featuring the first graphical user
interface (GUI) for IBM-compatible PCs, the Windows OS soon dominated the PC
market. Approximately 90 percent of PCs run some version of Windows.
The first version of
Windows, released in 1985 was simply a GUI offered as an extension of Microsoft’s
existing disk operating system or MS-DOS. Based in part on licensed concepts
that Apple Inc. had used for its Macintosh System Software, Windows for the
first time allowed DOS users to visually navigate a virtual desktop, opening
graphical ‘Windows’ displaying the contents of electronic folders and files
with the click of a mouse button, rather than typing commands and directory
paths at a text prompt.
Subsequent versions
introduced greater functionality, including native Windows File Manager,
Program Manager and Print Manager programs and a more dynamic interface.
Microsoft also developed specialized Windows packages, including the
networkable Windows for Workgroups and the high-powered Windows NT, aimed at
businesses. The 1995 consumer release Windows 95 fully integrated Windows and
DOS and offered built-in Internet support, including the World Wide Web browser
Internet Explorer.
With the 2001 release of
Windows XP, Microsoft united its various Windows packages under a single
banner, offering multiple editions for consumers, business, multimedia
developers and others. Windows XP abandoned the long-used Windows 95 kernel
(core software code) for a more powerful code base and offered a more practical
interface and improved application and memory management. The highly successful
XP standard was succeeded in late 2006 by Windows Vista, which experienced a
troubled rollout and met with considerable marketplace resistance, quickly
acquiring a reputation for being a large, slow and resource-consuming system.
Responding to Vista’s disappointment adoption rate. Microsoft developed Windows
7, an OS whose interface was similar to that of Vista but was met with
enthusiasm for its noticeable speed improvement and its modest system
requirements.
Windows
Vista
After a lengthy
development process. Windows Vista was released on November 30, 2006 for volume
licensing and January 30, 2007, for consumers. It contained a number of new
features, from a redesigned shell and user interface to significant technical
changes, with a particular editions and has been subject to some criticism,
such as drop of performance, longer boot time, criticism of new UAC and
stricter license agreement. Vista’s server counterpart, Windows Server 2008 was
released in early 2008.
Windows
7
On July 22, 2009 Windows
7 and Windows Server 2008 R2 were released as RTM (release to manufacturing)
while the former was released to the public 3 months later on October 22, 2009.
Unlike its predecessor Windows Vista, which introduced large number of new
features, Windows 7 was intended to be a more focused, incremental upgrade to
the Windows line, with the goal of being compatible with applications and
hardware with which Windows Vista was already compatible. Windows 7 has
multi-touch support, a redesigned Windows shell with an updated taskbar, a home
networking system called Home Group and performance improvements.
Windows
8 and 8.1
Windows 8, the successor
to Windows 7, was released generally on October 26, 2012. A number of
significant changes were made on Windows 8, including the introduction of a use
interface based around Microsoft’s Metro design language with optimizations for
touch-based devices such as tablets and all-in-one PCs. These changes include
the Start Screen, which uses large tiles that are more convenient for touch
interactions and allow for the display of continually updated information and a
new class of apps which are designed primarily for use on touch based devices.
Other changes include increased integration with cloud services and other
online platforms (such as social networks and Microsoft’s own Sky Drive and
Xbox Live series.), the Windows Store service for software distribution and a
new variant known as Windows RT for use on devices that utilize the RAM
architecture. An update to Windows 8, called Windows 8.1, was released on
October 17, 2013 and includes features such as new live tile sizes, deeper Sky
Drive integration and many some criticism, such as removal of Start Menu.
Windows
10
On September 30, 2014, Microsoft announced Windows 10 as the successor
to Windows 8.1. It was released on July 29, 2015 and addresses shortcomings in
the user interface first introduced with Windows 8. Changes include the return
of the Start Menu, a virtual desktop system and the ability to run Windows
Store apps within windows on the desktop rather than in full-screen mode.
Windows 10 is said to be available to update from qualified Windows 7 with SPI
and Windows 8.1 computers from the Get Windows 10 application.
Functions
of Windows operating system:
The basic functions of an operating system are:
i.
Booting
the computer
ii.
Performs
basic computer tasks e.g. managing the various peripheral devices e.g. mouse,
keyboard
iii.
Provides
a user interface, e.g. command line, graphical user interface (GUI)
iv.
Handless
system resources such as computer’s memory and sharing of the central
processing unit (CPU) time by various applications or peripheral devices
v.
Provides
file management which refers to the way that the operating system manipulates,
stores, retrieves and saves data.
Booting
the computer:
The process of starting
or restarting the computer is known as booting. A cold boot is when you turn on
a computer that has been turned off completely. A ward boot is the process of
using the operating system to restart the computer.
Performs
basic computer tasks:
The operating system
performs basic computer tasks, such as managing the various peripheral devices
such as the mouse, keyboard and printers. For example, most operating systems
now are plug and play which means a device such as a printer will automatically
be detected and configured without any user intervention.
Provides
a user interface:
A user interacts with
software through the user interface. The two main types of user interfaces are:
command line and a graphical user interface (GUI). With a command line
interface, the user interacts with the operating system by typing commands to
perform specific tasks. An example of a command line interface, the user
interacts with the operating system by using a mouse to access windows, icons,
and menus. An example of a graphical user interface is Windows Vista or Windows
7.
The operating system is
responsible for providing a consistent application program interface (API)
which is important as it allows a software developer to write an application on
one computer and know that it will run on another computer of the same type
even if the amount of memory or amount of storage is different on the two
machines.
Handless
System resources:
The operating system also
handles system resources such as the computer’s memory and sharing of the
central processing unit (CPU) time by various applications or peripheral
devices. Programs and input methods are constantly competing for the attention of
the CPU and demand memory, storage and input/output bandwidth. The operating
system ensures that each application gets the necessary resources it needs in
order to maximize the functionality of the overall system.
CHARACTERISTICS
OR FEATURES OF WINDOWS OPERATING SYSTEM
1. Speed:
Even aside from
incompatibilities and other issues that many people had with Vista, one of the
most straightforward was speed – it just felt too sluggish compared to XP, even
on pumped up hardware. Windows 7 brings a more responsive and sprightly feel
and Microsoft has spent a lot of time and effort getting the Start Menu
response just right.
Microsoft has
also recognized the need for improved desktop responsiveness, which gives the
impression that the computer is responding to the user and that they are in
control – something that was often lacking with Vista. You can also expect
faster boot times. And the boot sequence is now not only prettier than it was
with Vista, but it’s speedier too.
2. Compatibility:
In simple terms,
compatibility on Windows 7 will be far better than it was with Vista. Many
programs that individuals and companies used on Windows XP did not work
immediately and required updates, but with Windows 7 almost applications that
work on Vista should still run. In essence, Windows Vista has done most of the
hard work for Windows 7 in this respect.
3. Lower
hardware requirements:
Vista gained a
reputation for making even the beefiest hardware look rather ordinary. Windows
7, however, will run well on lower end hardware, making the transition from
Window XP less painful.
Microsoft is
even pushing Windows 7 for net books. This could provide a modern replacement
for Windows XP, which has found a new lease of life as the OS of choice on net
books, supplanting Linux. The downside is that Windows 7 starter edition, as it
will be called, will be limited to only three applications running at the same
time.3
4. Search
and organization:
One of the best
things about Windows 7 is the improved search tool, which now rivals Mac OS X’s
spotlight to be able to find what you need quickly and easily. For example,
typing ‘mouse’ will bring up the mouse option within the control panel or
typing a word will display it and split it up neatly into files, folders and
applications.
Also introduced
is the concept of Libraries, which takes the ‘My Documents’ concept a stage
further. The various Libraries, such as Documents and Pictures, will watch
multiple locations which you can add yourself, so you don’t have to keep
everything in one place.
5. Taskbar/Start
menu:
At first, the
taskbar looks like nothing has much has changed sinceVista. In fact, that’s not
the case and it’s a lot more powerful. Microsoft is now making best use of its
aero technology. By default taskbar icons are now larger and items are grouped
together and are not labeled with clumsy text.
The components of Pop-Up menu Start Button or
menu:
·
Programs
·
Documents
·
Settings
·
Help
& Support
·
Search
·
Run
·
Log off
·
Turn
off
The
important Icons of Desktop Screen:
·
My
Computer
·
My
Documents
·
Network
Places
·
Recycle
Bin
·
Internet
Explorer
Advantages
of Windows over DOS:
1.
DOS is
a character user interface or command line interface. Windows is a graphical
user interface.
2.
In DOS
the user has to remember and type so many commands. Commands executed by Icons
in windows.
3.
DOS do
not support multi tasking. Windows supports multitasking.
4.
DOS are
small OS. It cannot read hard disks with large capacities; Windows read hard
disks with very large capacity.
5.
Installing
new hardware devices is difficult. Installing hardware devices is very easy.
6.
DOS not
support multimedia. Windows support multimedia exhalent.
7.
There
is no security for data in DOS. Windows protect data with passwords.
8.
We
can’t access internet with using DOS. In windows easy to access to Internet.
MAC OS (MACINTOSH)
Mac OS is a series of
graphical user interface-based operating systems developed by Apple Inc. for
their Macintosh line of computer systems.
The original operating
system was system first introduced in 1984 as being integral to the original
Macintosh and referred to as the ‘System’. Referred to by its major revision
starting with ‘System 6’ and ‘System 7’, Apple re-branded version 7.6 as ‘Mac
OS’ a part of their Macintosh clone program in 1996.the Macintosh, specifically
its system software, is credited with having popularized the early graphical
user interface concept.
There have been two
operating systems popularly known as ‘Mac OS’. Up to major revision 10, from
2001 to present, is branded OS X (originally referred to as Mac OS X). Major
revisions to the Macintosh OS are now issued as point revisions, such that, for
example, 10.2 is substantially different from 10.5 both operating systems share
a general interface design and there has been some overlap of application
frameworks for compatibility; but the two systems have different origins and
use deeply different architectures.
Concept:
Apple’s original concept
for the Macintosh deliberately sought to minimize the user’s conceptual
awareness of the operating system. Tasks that required more operating system
knowledge on other systems would be accomplished by mouse gestures and graphic
controls on a Macintosh. This would differentiate it from then current systems,
such as MS-DOS, which used a command line interface consisting of
tersely-abbreviated textual commands.
The core of the system
software was held in ROM, with updates originally provided on floppy disk,
freely copy able at Apple dealers. The user’s involvement in an upgrade of the
operating system was also minimized to running an installer, or replacing
system files using the file manager. This simplicity was possible because the
early releases lacked any access controls, in effect giving its single user
root privileges at all times.
Versions:
Early versions of Mac OS
were compatible only with Motorola 68000-family Macintoshes. As Apple
introduced computers with Power PC hardware, the OS was ported to support this
architecture. Mac OS 8.1 was the last version that could run on a ‘68k’
processor (68040). OS X, which has superseded the ‘Classic’ Mac OS, is
compatible with only Power PC processors from version 10.0 (Cheetah) to version
10.3 (Panther). Both Power PC and Intel processors are supported in version
10.4 (Tiger, Intel only supported after an update) and version 10.5 (Leopard).
10.6 and later versions support only Intel processors.
The early Macintosh
operating system initially consisted of two user-visible components, called
‘System’ and ‘Finder’, each with its own version number, starting with version 5,
both were incorporated under a single ‘System Software’ moniker. System 7.5.1
was the first to include the Mac OS logo (a variation on the original Happy Mac
startup icon) and Mac OS 7.6 was the first to be named ‘Mac OS’. These changes
were made during the era of Macintosh clones, to disassociate the operating
system from Apple’s own Macintosh models.
Before the introduction
of the later PowerPC G3-based systems significant parts of the system were
stored in physical ROM on the motherboard. The initial purpose of this was to
avoid using up the limited storage of floppy disks on system support, given
that the early Macs had no hard disk (only one model of Mac was ever actually
bootable using the ROM alone, the 1991 Mac Classic model). This architecture
also allowed for a completely graphical OS interface at the lowest level
without the need for a text-only console or command-line mode. Boot time
errors, such as finding no functioning disk drives, were communicated to the
user graphically, usually with an icon or the distinctive Chicago bitmap font
and a Chime of Death or a series of beeps. This was in contrast to MS-DOS and
CP/M computers of the time, which displayed such messages in a mono-spaced font
on a black background and required the use of the keyboard, not a mouse, for
input. To provide such niceties at a low level, Mac OS depended on core system
software in ROM on the motherboard, a fact also used to ensure that only Apple
computers or licensed clones (with the copyright-protected ROMs from Apple)
could run Mac OS.
Macintosh
Clones:
Several computer
manufacturers over the years have made Macintosh clones capable running Mac OS.
From 1995 to 1997 Apple licensed Macintosh ROMs to several companies, notably Power
Computing, UMAX and Motorola. These machines normally ran various versions of
classic Mac OS. Steve Jobs ended the clone-licensing program after returning to
Apple in 1997.
In 2008, Miami-based
manufacturing company Psystar Corporation announced a $399 clone called Open
Mac that came with a barebones system that can run Mac OS X 10.5 Leopard.
Threatened with litigation, Psystar changed the name to Open Computer. Apple
filed a lawsuit with the company and asked that Psystar be ordered to stop
producing clone systems, recall every systems sold and pay monetary damages.
Eventually Apple prevailed in court and the Open Computer’s production was
ceased. Psystar itself appears to be defunct now, as the company’s website is
gone.
MOBILE APP
A mobile app is a
computer program designed to run on mobile devices such as smart phones and
tablet computers. Most such devices are sold with several apps included as
pre-installed software, such as a web browser, email client, calendar, mapping
program and an app for buying music or other media or more apps. Some
pre-installed apps can be removed by an ordinary uninstall process, thus leaving
more storage space for desired ones. Where the software does not allow this,
some devices can be rooted to eliminate the undesired apps.
Apps that are not
preinstalled are usually available through application distribution platforms,
which began appearing in 2008 and are typically operated by the owner of the
mobile operating system, such as the Apple App Store, Google Play, Windows
Phone Store and Black Berry App World. Some apps are free, while others must be
bought. Usually they are downloaded from the platform to a target device, but
sometimes they can be downloaded to laptops or desktop computers. For apps with
a price, generally a percentage, 20-30% goes to the distribution provider such
as iTunes and the rest goes to the producer of the app. The same app can
therefore cost the average Smart phone user a different price depending on
whether they use iPhone, Android or BlackBerry 10 devices.
The term ‘app’ is a
shortening of the term ‘application’ software. It has become very popular and
in 2010 was listed as ‘Word of the Year’ by the American Dialect Society. In
2009, technology columnist David Pogue said that newer smart phones could be
nicknamed ‘app phones’ to distinguish them from earlier less-sophisticated
smart phones. Mobile apps were originally offered for general productivity and
information retrieval, including email, calendar, contacts, stock market and
weather information. However, public demand and the availability of developer
tools drove rapid expansion into other categories, such as those handled by
desktop application software packages. As with other software, the explosion in
number and variety of apps made discovery a challenge, which in turn led to the
creation of a wide range of review, recommendation and curtain sources,
including blogs, magazines and dedicated online app-discovery services. In 2014
government regulatory agencies began trying to regulate and curate apps,
particularly medical apps. Some companies offer apps as an alternative method
to deliver content (media) with certain advantages over an official website.
Usage of mobile apps has
become increasingly prevalent across mobile phone users. A may 2012 COM score
study reported that during the previous quarter, more mobile subscribers used
apps than browsed the web on their devices: 51.1% Vs 49.8% respectively.
Researchers found that usage of mobile apps strongly correlates with user
context and depends on user’s location and time of the day. Market research
firm Gartner predicted that 102 billion apps would be downloaded in 2013 (91%
of them free), generating US$26 billion, up 44.4% on 2012’s US$18 billion. An
analyst report estimates that the app economy creates revenues of more than £10 billion per year within the European Union, while over 529,000
jobs have been created in 28 EU states due to the growth of the app market.
Developing apps for
mobile devices requires considering the constraints and features of these
devices. Mobile devices run on battery and have less powerful processors than
personal computers and also have more features such as location detection and
cameras. Developers also have to consider a wide array of screen sizes,
hardware specifications and configurations because of intense competition in
mobile software and changes within each of the platforms.
Mobile application
development requires use of specialized integrated development environments.
Mobile apps are first tested within the development environment using emulators
and later subjected to field testing. Emulators provide an inexpensive way to
test applications on mobile to which developers may not have physical access.
As part of the
development process, mobile user interface (UI) Design is also an essential in
the creation of mobile apps. Mobile UI considers constraints and contexts,
screen, input and mobility as outlines for design. The user is often the focus
of interaction with their device and the interface entails components of both
hardware and software. User input allows for the users to manipulate a system
and device’s output allows the system to indicate the effects of the users
manipulation. Mobile UI design constraints include limited attention and form
factors, such as a mobile device’s screen size for a user’s hand. Mobile UI
contexts signal cues from user interactions within a mobile application.
Overall, mobile UI design’s goal is primarily for an understandable,
user-friendly interface.
Mobile UIs, or
front-ends, rely on mobile back-ends to support access to enterprise systems.
The mobile back-end facilitates data routing, security, authentication,
authorization, working off-line and service orchestration. This functionality
is supported by a mix of middleware components including mobile app services,
Mobile Backend as a service and SOA infrastructure.
The two biggest app stores are Google Play for
Android and Apple Store for iOS
Google
Play:
Google Play formerly
known as the Android Market is an international online software store developed
by Google for Android devices. It opened in October 2008. In August 2014, there
were approximately 1.3+ million apps available for Android and the estimated
number of applications downloaded from Google Play was 40 billion.
According to
Statista.com, statistic shows the number of available applications in the
Google Play Store, formerly known as Android Market, from December 2009 to
February 2015. In May 2012, the number of available apps in the Google Play
Store surpassed 1 million apps in July 2013 and was most recently placed at 1.4
million apps in February 2015.
App
Store:
Apple’s App Store for iOS
was not the first app distribution service but it ignited the mobile revolution
and was opened on July 10, 2008 and as of January 2011, reported over 10
billion downloads. the original App Store was first demonstrated to Steve Jobs
in 1993 by Jesses Taylor at NeXT World Expo As of June 6, 2011, there were
425,000 apps available, which had been downloaded by 200 million iOS users.
during Apple’s 2012 Worldwide Developers Conference, Apple CEO Tim Cook
announced that the App Store has 650,000 available apps to download as well as
30 billion apps downloaded from the app store until the date. from an
alternative perspective, figures seen in July 2013 by the BBC from tracking
service Adeven indicate over two-thirds of apps in the store are ‘Zombies’
barely ever installed by costumers.
Others:
·
Amazon
App Store is an alternative application store for the Android operating system.
It was opened in March 2011, with 3800 applications. The Amazon App store’s
Android Apps can also run on BlackBerry 10 devices.
·
Black
Berry World is the application store for BlackBerry 10 and BlackBerry OS
devices. It opened in April 2009 as BlackBerry App World and as of February
2011, was claiming the largest revenue per app: $9,166.67 compared to $6,480.00
at the Apple App Store and $1,200 in the downloads per day and 1 billion total
downloads. In May 2013, BlackBerry World reached over 120,000 apps. BlackBerry
10 users can also run Android apps.
·
Ovi
(Nokia) for Nokia phones was launched interationally in May 2009. In May 2011,
Nokia announced plans to re-brand its Ovi product line under the Nokia brand
and Ovi Store was renamed Nokia Store in October 2011. Nokia Store will no
longer allow and Mee Go operating systems from January 2014.
·
Windows
Phone Store was introdubed by Microsoft for its Windows Phone platform, which
was launched in October 2010. As of October 2012, it has over 120,000 apps
available.
·
Windows
Store was introduced by Microsoft for its Windows Phone platform, which was
launched in October 2010. As of October 2012, it has over 120,000 apps
available.
·
Windows
Store was introduced by Microsoft for its Windows 8 and Windows RT platforms.
While it can also carry listings for traditional desktop programs certified for
compatibility with Windows 8, it is primarily used to distribute Windows Store
Apps – which are primarily built for use on tables and other touch based
devices but can still be used with a keyboard and mouse and on desktop
computers and laptops.
·
Samsung
Apps was founded in September 2009. As of October 2011, Samsung Apps reached 10
million downloads. The store is available in 125 countries and it offers apps
for Windows Mobile, Android and Big platforms.
·
The
Electronic App Wrapper was the first electronic distribution service to
collectively provide encryption and purchasing electronically.
·
There
are many other independent app stores for Android devices Now a days so many
different types app zones are available for android mobiles. They are:
-
Shopping
-
Student
Zone
-
News
Zone
-
Photo
Zone
-
Music
Zone
-
Video
Zone
-
Story
& Fun Zone
-
Life
Style Zone
Advantages
of Mobile Apps:
1.
Internet
browsing is very easy without any knowledge to use mobile apps.
2.
Professional
Mobile Application Management helps companies protect their data. One option
for securing corporate data.
3.
Very
easy to download games to compare internet.
4.
Updating
of the softwares is very easy to use app.
5.
Easy to
send messages to others free of cost.
6.
Banking,
recharge very easy.
7.
Shopping
any item is easy.
8.
Photo
framing and change of background is easy to use apps like Photo Editor, Photo
Collage Art etc.
