Microsoft Windows is a series of
software operating
systems and
graphical user
interfaces produced by
Microsoft.
Microsoft first introduced an operating environment named
Windows in November 1985 as an add-on to
MS-DOS in response to the growing interest in
graphical user interfaces
(GUIs). Microsoft Windows came to
dominate the world's
personal computer market, overtaking
Mac OS, which had been introduced previously.
As of October 2009, Windows had approximately 91% of the market
share of the
client operating
systems for usage on the Internet. The most recent client version
of Windows is
Windows 7; the most recent
server version is
Windows Server 2008 R2.
Versions
The term
Windows collectively describes any or all of
several generations of
Microsoft operating system products. These products
are generally categorized as follows:
Early versions
The history of Windows dates back to September 1981, when the
project named "Interface Manager" was started. It was announced in
November 1983 (after the
Apple Lisa, but
before the
Macintosh) under the name
"Windows", but
Windows 1.0 was not
released until November 1985. The
shell of Windows 1.0 was a program
known as the
MS-DOS Executive.
Other supplied programs are
Calculator,
Calendar,
Cardfile,
Clipboard viewer,
Clock,
Control Panel,
Notepad,
Paint,
Reversi,
Terminal, and
Write.
Windows 1.0 does not allow overlapping
windows, due to Apple
Computer
owning this feature . Instead all windows
are
tiled. Only dialog boxes
can appear over other windows.
Windows 2.0 was released in October 1987
and featured several improvements to the user interface and memory
management. Windows 2.0 allowed application windows to overlap each
other and also introduced more sophisticated keyboard-shortcuts. It
could also make use of
expanded
memory.
Windows 2.1 was released in two different flavors:
Windows/386 employed the
386
virtual 8086 mode to multitask
several DOS programs, and the paged memory model to emulate
expanded memory using available
extended
memory.
Windows/286 (which, despite
its name, would run on the 8086) still ran in
real mode, but could make use of the
high memory area.
The early versions of Windows were often thought of as simply
graphical user interfaces, mostly because they ran on top of
MS-DOS and used it for
file system services. However, even the earliest
16-bit Windows versions already assumed many typical operating
system functions; notably, having their own
executable file format and providing
their own
device drivers (timer,
graphics, printer, mouse, keyboard and sound) for applications.
Unlike
MS-DOS, Windows allowed users to
execute multiple graphical applications at the same time, through
cooperative multitasking.
Windows implemented an elaborate, segment-based, software virtual
memory scheme, which allowed it to run applications larger than
available memory: code segments and
resource were swapped in and thrown away
when memory became scarce, and data segments moved in memory when a
given application had relinquished processor control, typically
waiting for user input.
Windows 3.0 and 3.1
Windows 3.0 (1990) and
Windows 3.1 (1992) improved the design, mostly
because of
virtual memory and
loadable virtual device drivers (
VxDs) which
allowed them to share arbitrary devices between multitasked DOS
windows. Also, Windows applications could now run in protected mode
(when Windows was running in Standard or 386 Enhanced Mode), which
gave them access to several megabytes of memory and removed the
obligation to participate in the software virtual memory scheme.
They still ran inside the same address space, where the segmented
memory provided a degree of protection, and multi-tasked
cooperatively. For Windows 3.0, Microsoft also rewrote critical
operations from
C into
assembly, making this release
faster and less memory-hungry than its predecessors. With the
introduction of the
Windows for Workgroups
3.11, Windows was able to bypass DOS for file management
operations using
32-bit file
access.
Windows 95, 98, and Me
Windows 95 was released in 1995,
featuring a new user interface, support for
long file names of up to 250 characters, and
the ability to automatically detect and configure installed
hardware (
plug and play). It can
natively run 32-bit applications, and features several
technological improvements that increased its stability over
Windows 3.1. There were several OEM Service Releases (OSR) of
Windows 95, each of which was roughly equivalent to a
service pack.
Microsoft's next release was
Windows 98
in 1998. Microsoft released a second version of Windows 98 in 1999,
named
Windows 98
Second Edition (often shortened to Windows 98 SE).
In 2000, Microsoft released
Windows Me
(
Me standing for
Millennium Edition), which
updated the core from Windows 98 but adopted some aspects of
Windows 2000 and removed the "boot in
DOS mode" option. It also added a new feature called
System Restore, allowing the user to set the
computer's settings back to an earlier date.
Windows NT family
The NT family of Windows systems was fashioned and marketed for
higher reliability business use. The first release was MS
Windows NT 3.1 (1993), numbered "3.1" to
match the consumer Windows version, which was followed by
NT 3.5 (1994),
NT
3.51 (1995),
NT 4.0 (1996), and
Windows 2000 (2000). 2000 is the last
NT-based Windows release which does not include Microsoft
Product Activation. NT 4.0 was the first
in this line to implement the "Windows 95" user interface (and the
first to include Windows 95’s built-in 32-bit runtimes). Microsoft
then moved to combine their consumer and business operating systems
with
Windows XP, coming in both home and
professional versions (and later niche market versions for
tablet PCs and
media
centers); they also diverged release schedules for server
operating systems.
Windows Server
2003, released a year and a half after Windows XP, brought
Windows Server up to date with MS
Windows XP. After a lengthy
development process,
Windows Vista was released toward the end of
2006, and its server counterpart,
Windows Server 2008 was released in
early 2008. On July 22, 2009,
Windows 7
and
Windows Server 2008 R2
were released as RTM (release to manufacturing).
Windows 7 was released on October 22 2009.
Windows CE, Microsoft’s offering in the
mobile and embedded markets, is also a true 32-bit operating system
that offers various services for all sub-operating
workstations.
64-bit operating systems
Windows NT included support for several
different platforms before the
x86-based
personal computer became dominant in the
professional world.
Versions of NT from 3.1 to 4.0 variously
supported PowerPC, DEC
Alpha and MIPS
R4000, some
of which were 64-bit processors, although the operating system
treated them as 32-bit processors.
With the
introduction of the Intel
Itanium architecture, which is referred to as
IA-64, Microsoft released new versions of
Windows to support it. Itanium versions of
Windows XP and
Windows Server 2003 were released at the
same time as their mainstream x86 (32-bit) counterparts. On April
25, 2005, Microsoft released
Windows XP Professional x64
Edition and x64 versions of Windows Server 2003 to support the
x86-64 (or
x64 in Microsoft
terminology) architecture. Microsoft dropped support for the
Itanium version of Windows XP in 2005.
Windows Vista is the first end-user version of
Windows that Microsoft has released simultaneously in x86 and x64
editions. Windows Vista does not support the Itanium architecture.
The modern 64-bit Windows family comprises AMD64/Intel64 versions
of
Windows Vista, and
Windows Server 2008, in both Itanium and
x64 editions. Windows Server 2008 R2 drops the 32-bit version,
although
Windows 7 does not.
Windows CE
Windows CE (officially known as Windows Embedded), is an edition of
Windows that runs on minimalistic computers, like satellite
navigation systems and, uncommonly, mobile phones. Windows Embedded
runs as CE, rather than NT, which is why it should not be mistaken
for Windows XP Embedded, which is NT. Windows CE was used in the
Dreamcast along with Sega's own
proprietary OS for the console.
History
The Windows family tree.
Microsoft has taken two parallel routes in its operating systems.
One route has been for the home user and the other has been for the
professional IT user. The dual routes have generally led to home
versions having greater
multimedia
support and less functionality in networking and security, and
professional versions having inferior multimedia support and better
networking and security.
The first version of Microsoft Windows,
version 1.0, released in November 1985, lacked a
degree of functionality and achieved little popularity, and was to
compete with Apple’s own operating system. Windows 1.0 is not a
complete operating system; rather, it extends MS-DOS. Microsoft
Windows version 2.0 was released in November, 1987 and was slightly
more popular than its predecessor. Windows 2.03 (release date
January 1988) had changed the OS from tiled windows to overlapping
windows. The result of this change led to Apple Computer filing a
suit against Microsoft alleging infringement on Apple's
copyrights.
Microsoft Windows version 3.0, released in 1990, was the first
Microsoft Windows version to achieve broad commercial success,
selling 2 million copies in the first six months. It featured
improvements to the user interface and to multitasking
capabilities. It received a facelift in Windows 3.1, made generally
available on March 1, 1992. Windows 3.1 support ended on December
31, 2001.
In July 1993, Microsoft released
Windows
NT based on a new kernel. NT was considered to be the
professional OS and was the first Windows version to utilize
preemptive multitasking. .
Windows NT would later be retooled to also function as a home
operating system, with Windows XP.
On August 24, 1995, Microsoft released
Windows 95, a new, and major, consumer version
that made further changes to the user interface, and also used
preemptive multitasking.
Windows 95 was designed to replace not only Windows 3.1, but also
Windows for Workgroups, and MS-DOS. It was also the first Windows
operating system to use Plug and Play capabilities. The changes
Windows 95 brought to the desktop were revolutionary, as opposed to
evolutionary, such as those in Windows 98 and Windows Me.
Mainstream support for
Windows 95 ended
on December 31, 2000 and extended support for
Windows 95 ended on December 31, 2001.
The next in the consumer line was Microsoft
Windows 98 released on June 25, 1998. It was
substantially criticized for its slowness and for its unreliability
compared with
Windows 95, but many of its
basic problems were later rectified with the release of
Windows 98 Second Edition in 1999. Mainstream
support for
Windows 98 ended on June 30,
2002 and extended support for
Windows 98
ended on July 11, 2006.
As part of its "professional" line, Microsoft released
Windows 2000 in February 2000. The consumer
version following Windows 98 was
Windows
Me (Windows Millennium Edition). Released in September 2000,
Windows Me implemented a number of new
technologies for Microsoft: most notably publicized was "
Universal Plug and Play". During
2004 part of the Source Code for Windows 2000 was leaked onto the
internet. This was bad for Microsoft as the same kernel used in
Windows 2000 was used in Windows XP.
In October 2001, Microsoft released
Windows
XP, a version built on the Windows NT
kernel that also retained the
consumer-oriented usability of Windows 95 and its successors. This
new version was widely praised in computer magazines. It shipped in
two distinct editions, "Home" and "Professional", the former
lacking many of the superior security and networking features of
the Professional edition. Additionally, the first "Media Center"
edition was released in 2002, with an emphasis on support for DVD
and TV functionality including program recording and a remote
control. Mainstream support for
Windows
XP ended on April 14, 2009. Extended support will continue
until April 8, 2014.
In April 2003,
Windows Server
2003 was introduced, replacing the
Windows 2000 line of server products with a
number of new features and a strong focus on security; this was
followed in December 2005 by Windows Server 2003 R2.
On January 30, 2007 Microsoft released
Windows Vista. It contains a number of
new features, from a
redesigned shell and user interface to significant
technical changes,
with a particular focus on
security
features. It is available in a number of
different editions, and
has been subject to
some
criticism.
Timeline of releases
Security
Consumer versions of Windows were originally designed for
ease-of-use on a single-user PC without a network connection, and
did not have security features built in from the outset. However,
Windows NT and its successors are
designed for security (including on a network) and multi-user PCs,
but were not initially designed with Internet security in mind as
much, since, when it was first developed in the early 1990s,
Internet use was less prevalent.
These design issues combined with programming errors (e.g.
buffer overflows) and the popularity of
Windows means that it is a frequent target of
computer worm and
virus writers. In June 2005,
Bruce Schneier’s
Counterpane Internet
Security reported that it had seen over 1,000 new viruses and
worms in the previous six months.
Microsoft releases security patches through its
Windows Update service approximately once a
month (usually the second Tuesday of the month), although critical
updates are made available at shorter intervals when necessary. In
versions of Windows after and including Windows 2000 SP3 and
Windows XP, updates can be automatically downloaded and installed
if the user selects to do so. As a result, Service Pack 2 for
Windows XP, as well as Service Pack 1 for Windows Server 2003, were
installed by users more quickly than it otherwise might have
been.
While the
Windows 9x series offered the
option of having profiles for multiple users, they had no concept
of
access privileges,
and did not allow concurrent access; and so were not true
multi-user operating systems. In addition, they
implemented only partial
memory
protection. They were accordingly widely criticised for lack of
security.
The
Windows NT series of operating
systems, by contrast, are true multi-user, and implement absolute
memory protection. However, a lot of the advantages of being a true
multi-user operating system were nullified by the fact that, prior
to
Windows Vista, the first user
account created during the setup process was an
administrator account, which was also
the default for new accounts. Though
Windows
XP did have limited accounts, the majority of home users did
not change to an account type with fewer rights – partially due to
the number of programs which unnecessarily required administrator
rights – and so most home users ran as administrator all the
time.
Windows Vista changes this by
introducing a privilege elevation system called
User Account Control. When logging in
as a standard user, a logon session is created and a
token containing only the
most basic privileges is assigned. In this way, the new logon
session is incapable of making changes that would affect the entire
system. When logging in as a user in the Administrators group, two
separate tokens are assigned. The first token contains all
privileges typically awarded to an administrator, and the second is
a restricted token similar to what a standard user would receive.
User applications, including the
Windows
Shell, are then started with the restricted token, resulting in
a reduced privilege environment even under an Administrator
account. When an application requests higher privileges or "Run as
administrator" is clicked, UAC will prompt for confirmation and, if
consent is given (including administrator credentials if the
account requesting the elevation is not a member of the
administrators group), start the process using the unrestricted
token.
Windows File Permissions
All Windows versions from Windows NT 3 have been based on a file
system permission system referred to as AGLP (Accounts, Global,
Local, Permissions)
AGDLP which in essence
where file permissions are applied to the file/folder in the form
of a 'local group' which then has other 'global groups' as members.
These global groups then hold other groups or users depending on
different Windows versions used. This system varies from other
vendor products such as Linux and NetWare due to the 'static'
allocation of permission being applied directory to the file or
folder. However using this process of AGLP/AGDLP/AGUDLP allows a
small number of static permissions to be applied and allows for
easy changes to the account groups without reapplying the file
permissions on the files and folders.
Windows Defender
On January 6, 2005, Microsoft released a
Beta version of Microsoft AntiSpyware, based
upon the previously released
Giant AntiSpyware. On February 14,
2006, Microsoft AntiSpyware became
Windows Defender with the release of Beta
2. Windows Defender is a freeware program designed to protect
against spyware and other unwanted software.
Windows XP and
Windows Server 2003 users who have
genuine copies of
Microsoft Windows can freely download the program from Microsoft's
web site, and Windows Defender ships as part of
Windows Vista and 7.
Third-party analysis
In an article based on a report by Symantec, internetnews.com has
described Microsoft Windows as having the "fewest number of patches
and the shortest average patch development time of the five
operating systems it monitored in the last six months of
2006."
A study conducted by
Kevin Mitnick and
marketing communications firm Avantgarde in 2004 found that an
unprotected and unpatched Windows XP system with Service Pack 1
lasted only 4 minutes on the Internet before it was compromised,
and an unprotected and also unpatched
Windows Server 2003 system was
compromised after being connected to the internet for 8 hours.
However, it is important to note that this study does not apply to
Windows XP systems running the Service Pack 2 update (released in
late 2004), which vastly improved the security of Windows XP. The
computer that was running Windows XP Service Pack 2 was not
compromised. The
AOL National Cyber Security
Alliance Online Safety Study of October 2004 determined that 80% of
Windows users were infected by at least one
spyware/
adware product. Much
documentation is available describing how to increase the security
of Microsoft Windows products. Typical suggestions include
deploying Microsoft Windows behind a hardware or software
firewall, running
anti-virus and
anti-spyware software, and installing patches
as they become available through
Windows
Update.
Emulation software
Emulation allows the use of some Windows applications without using
Microsoft Windows. These include:
- Wine — a free and open source software
implementation of the Windows API,
allowing one to run many Windows applications on x86-based
platforms, including Linux and Mac OS X. Wine developers refer to it as a
"compatibility layer"; and make use of Windows-style APIs to
emulate the Windows environment.
- CrossOver — A Wine package with
licensed fonts. Its developers are regular contributors to Wine,
and focus on Wine running officially supported applications.
- Cedega — TransGaming Technologies'
proprietary fork of
Wine, designed specifically for running games written for Microsoft
Windows under Linux. A version of Cedega known as Cider is used by some video
game publishers to allow Windows games to run on Mac OS X. Since
wine was licensed under the LGPL Cedega has been unable to port the
improvements made to wine to their proprietary codebase.
- Darwine — A bundling of Wine to the
PowerPC Macs
running OS X by running wine on top of
QEMU. Intel Macs use the same Wine as other *NIX
x86 systems.
- ReactOS — An open-source OS that is
intended to run the same software as Windows, originally designed
to simulate Windows NT 4.0, now aiming at Windows XP compatibility.
It has been in the development
stage since 1996.
See also
General:
Further reading:
References
- Petzold
- AT (formerly XiTi) recently changed its methodology, making
these statistics not directly comparable with its earlier
reports.
- Windows 3.1 Standard Edition Support
Lifecycle
- Windows 95 Support Lifecycle
- Windows 98 Standard Edition Support
Lifecycle
- Your top Windows XP questions answered! (Part
One)
- Paul Thurrott's SuperSite for Windows: A Look at
Freestyle and Mira
- Windows XP Professional Lifecycle Support
- Multi-user memory protection was not introduced until Windows
NT and XP, and a computer's default user was an administrator until
Windows Vista. Source: UAC msdn
- Microsoft describes in detail the steps taken to combat this in
a TechNet bulletin. [1]
- 5 Steps to Securing Your Windows XP Home
Computer
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