Microsoft Windows

From Wikipedia, the free encyclopedia


Microsoft Windows
Windows logo
Windows 7 desktop
Windows 7 desktop
Company / developer Microsoft
OS family MS-DOS/Windows 9x-based, Windows CE, Windows NT
Working state Publicly released
Source model Closed source / Shared source
Latest stable release Windows 7, Windows Server 2008 R2
NT 6.1 Build 7600 (7600.16385.090713-1255)  (2009-10-22; 2 months ago) [+/−]
Latest unstable release [+/−]
License MS-EULA
Website Official website


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).[1] 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.[2][3][4] The most recent client version of Windows is Windows 7; the most recent server version is Windows Server 2008 R2; the most recent mobile device version is Windows Mobile 6.5.


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.[5] The shell of Windows 1.0 was a program known as the MS-DOS Executive. Other supplied programs were Calculator, Calendar, Cardfile, Clipboard viewer, Clock, Control Panel, Notepad, Paint, Reversi, Terminal, and Write. Windows 1.0 did not allow overlapping windows, due to Apple Computer owning this feature[citation needed]. Instead all windows were tiled. Only dialog boxes could appear over other windows.
Windows 2.0 was released in October 1987 and featured several improvements to the user interface and memory management.[5] 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.[6] 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 resources 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.[citation needed]

Windows 3.0 and 3.1

Windows OS market share
Source  ↓ HitsLink[7]  ↓ Awio[8]  ↓ StatCounter[9]  ↓
Date December 2009 December 2009 December 2009
All versions 92.16% 86.43% 93.35%
Windows XP 67.77% 56.61% 65.12%
Windows Vista 17.87% 21.29% 22.02%
Windows 7 5.71% 6.80% 6.21%
Windows 2000 0.62% 0.50%
Windows 98 0.09% 0.09%
Windows Me 0.05%
Windows CE 0.05%
Windows Server 2003 1.14%

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.[citation needed] 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.[citation needed] 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 could natively run 32-bit applications, and featured 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 computerPowerPC, DEC Alpha and MIPS R4000, some of which were 64-bit processors, although the operating system treated them as 32-bit processors. became dominant in the professional world. Versions of NT from 3.1 to 4.0 variously supported
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. Windows CE is the core from which Windows Mobile is derived.

Timeline of releases

Release date Product name Current Version / Build Notes Last IE
November 1985 Windows 1.01 1.01 Unsupported -
November 1987 Windows 2.03 2.03 Unsupported -
May 1988 Windows 2.10 2.10 Unsupported. -
March 1989 Windows 2.11 2.11 Unsupported. -
May 1990 Windows 3.0 3.0 Unsupported -
March 1992 Windows 3.1x 3.1 Unsupported 5
October 1992 Windows For Workgroups 3.1 3.1 Unsupported 5
July 1993 Windows NT 3.1 NT 3.1 Unsupported 5
December 1993 Windows For Workgroups 3.11 3.11 Unsupported 5
January 1994 Windows 3.2 (released in Simplified Chinese only) 3.2 Unsupported 5
September 1994 Windows NT 3.5 NT 3.5 Unsupported 5
May 1995 Windows NT 3.51 NT 3.51 Unsupported 5
August 1995 Windows 95 4.0.950 Unsupported 5.5
July 1996 Windows NT 4.0 NT 4.0.1381 Unsupported 6
June 1998 Windows 98 4.10.1998 Unsupported 6
May 1999 Windows 98 SE 4.10.2222 Unsupported 6
February 2000 Windows 2000 NT 5.0.2195 Extended Support until July 13, 2010[20] 6
September 2000 Windows Me 4.90.3000 Unsupported 6
October 2001 Windows XP NT 5.1.2600 Extended Support until July 13, 2010 for SP2 and April 8, 2014 for SP3. (RTM and SP1 unsupported). 8
March 2003 Windows XP 64-bit Edition (IA-64) NT 5.2.3790 Unsupported 6
April 2003 Windows Server 2003 NT 5.2.3790 Current for SP1, R2, SP2 (RTM unsupported). 8
April 2005 Windows XP Professional x64 Edition NT 5.2.3790 Current 8
July 2006 Windows Fundamentals for Legacy PCs NT 5.1.2600 Current 8
November 2006 (volume licensing)
January 2007 (retail)
Windows Vista NT 6.0.6002 Current
Version changed to NT 6.0.6001 with SP1 (February 4, 2008) and to NT 6.0.6002 with SP2 (April 28, 2009).
July 2007 Windows Home Server NT 5.2.4500 Current 8
February 2008 Windows Server 2008 NT 6.0.6002 Current
Version changed to NT 6.0.6002 with SP2 (April 28, 2009).
October 2009 [21] Windows 7 and Windows Server 2008 R2 NT 6.1.7600 Current 8
2012 Windows 8 Unknown Upcoming Unknown


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.[22] However, Windows NT[23] 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.[24]
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.[25] 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.[26]
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[27] 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.[28]

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 DefenderWindows 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.[29] with the release of Beta 2. Windows Defender is a freeware program designed to protect against spyware and other unwanted software.

Third-party analysis

In an article based on a report by Symantec,[30] 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."[31]
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.[32] 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.[citation needed] 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[33] 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.[34] product.


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";[35] 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.
    • CedegaTransGaming 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.




No comments:

Post a Comment

Related Posts with Thumbnails