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Microsoft Windows is a family of operating systems by Microsoft. They can run on several types of platforms such as servers, embedded devices and, most typically, on personal computers. Microsoft first introduced an operating environment named Windows in November 1985 as an add-on to MS-DOS in response to the growing trend of graphical user interfaces (GUI) popularized by the Macintosh. Microsoft Windows eventually came to dominate the world's personal computer market. At the 2004 IDC Directions conference, IDC Vice President Avneesh Saxena stated that Windows had approximately 90% of the client operating system market.
Versions The term Windows collectively describes any or all of several generations of Microsoft (MS) operating system (OS) products. These products are generally categorized as follows: 16-bit operating environments The early versions of Windows were often thought of as just graphical user interfaces or desktops, mostly because they were started from 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. Finally, 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. Examples include Windows 1.0 (1985) and Windows 2.0 (1987) and its close relative Windows/286. Hybrid 16/32-bit operating environments Windows/386 introduced a 32-bit protected mode kernel and virtual machine monitor. For the duration of a Windows session, it created one or more virtual 8086 environments and provided device virtualization for the video card, keyboard, mouse, timer and interrupt controller inside each of them. The user-visible consequence was that it became possible to preemptively multitask multiple MS-DOS environments in separate windows (graphical applications required switching the window to full screen mode). Windows applications were still multi-tasked cooperatively inside one of such real-mode environments. Windows 3.0 (1990) and Windows 3.1 (1992) improved the design, mostly thanks to virtual memory and loadable virtual device drivers (VxDs) which allowed them to share arbitrary devices between multitasked DOS windows. Because of this, Windows applications could now run in 16-bit 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. Hybrid 16/32-bit operating systems With the introduction of 32-bit File Access in Windows for Workgroups 3.11, Windows could finally stop relying on DOS for file management. Leveraging this, Windows 95 introduced Long File Names, reducing the 8.3 DOS to the role of a boot loader. MS-DOS was now bundled with Windows; this notably made it (partially) aware of long file names when its utilities were run from within Windows, but angered the competition. The most important novelty was the possibility of running 32-bit multi-threaded preemptively multitasked graphical programs. However, the necessity of keeping compatibility with 16-bit programs meant the GUI components were still 16-bit only and not fully reentrant, which resulted in reduced performance and stability. There were three releases of Windows 95 (the first in 1995, then subsequent bug-fix versions in 1996 and 1997, only released to OEMs, which added extra features such as FAT32 support). Microsoft's next OS was Windows 98; there were two versions of this (the first in 1998 and the second, named "Windows 98 Second Edition", in 1999). In 2000, Microsoft released Windows Me (Me standing for Millennium Edition), which used the same core as Windows 98 but adopted the visual appearance of Windows 2000, as well as a new feature called System Restore, allowing the user to set the computer's settings back to an earlier date. It was not a very well received implementation, and many user problems occurred. Windows Me was considered a stopgap to the day both product lines would be seamlessly merged. Microsoft left little time for Windows Me to become popular before announcing their next version of Windows which would be called Windows XP. 32-bit operating systems This family of Windows systems was designed and marketed for higher-reliability business use, and was unencumbered by any Microsoft DOS heritage. The first release was Windows NT 3.1 (1993, numbered "3.1" to match the Windows version and to one-up OS/2 2.1, IBM's flagship OS codeveloped by Microsoft and Windows NT's main competitor at the time), which was followed by NT 3.5 (1994), NT 3.51 (1995), and NT 4.0 (1996); the latter implemented the Windows 95 user interface. Microsoft then moved to combine their consumer and business operating systems. Their first attempt, Windows 2000, failed to meet their goals, and was released as a business system. The home consumer edition of Windows 2000, codenamed "Windows Neptune", ceased development and Microsoft released Windows Me in its place. Eventually "Neptune" was merged into their new project, Whistler, which later became Windows XP. Since then, a new business system, Windows Server 2003, has expanded the top end of the range, and the forthcoming Windows Vista will complete it. Windows CE, Microsoft's offering in the mobile and embedded markets, is also a true 32-bit operating system. 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 supported DEC Alpha and MIPS R4000, which were 64-bit processors, although the operating system treated them as 32-bit processors. With the introduction of the IA-64 (Itanium) architecture, and later the AMD64/EM64T (or x64 in Microsoft terminology) architectures, Microsoft released new versions of its more contemporary operating systems to support them. The modern 64-bit Windows family comprises Windows XP 64-bit Edition for IA-64 systems, Windows XP Professional x64 Edition for AMD64/EM64T systems, and Windows Server 2003, in both IA-64 and x64 editions. The x64 versions of Windows XP Professional and Server 2003 were released on April 25 2005, while the IA-64 versions were released at the same time as their mainstream x86 (32-bit) counterparts. Windows Vista will be the first end-user version of Windows that Microsoft plans to release simultaneously in 32-bit and x64 editions. History
Security Security has been a major weakness of Windows for many years, and even Microsoft itself has been the victim of security breaches.• Due in some part to the widespread usage of Windows on personal computers as well as a number of technical reasons there is reportedly a five-fold greater amount of malware for Windows than other operating systems such as GNU/Linux, Unix, Mac OS X, and FreeBSD•. Windows was 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. Windows NT and its successors are designed for security (including on a network) and multi-user PCs, but was not designed for Internet security in mind as much since, when it was first developed, the Internet was less important. Combined with occasionally flawed code (such as buffer overflows), Windows is a frequent target of worms and virus writers. Furthermore, until Windows Server 2003 most versions of even Windows NT were shipped with important security features disabled by default, and vulnerable (albeit useful) system services enabled by default. 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 publicly admitted their ongoing security problems shortly after the turn of the century and now claims to regard security as their number one priority. The much-needed Automatic Update came first with Windows Me. As a result, Service Pack 2 for Windows XP, as well as Windows Server 2003, was installed by users more quickly than it might have been. 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 Windows 2000 (SP3 and later), Windows XP and Windows Server 2003, updates can be automatically downloaded and installed if the user selects to do so. Windows Defender On 6 January 2005, Microsoft released a beta version of Windows AntiSpyware, based upon the previously released Giant AntiSpyware. On 14 February 2006, Windows 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. Paul Thurrott's Supersite for Windows gave Defender Beta 2 a stellar review•; it received more middling reviews from other publications such as PC Magazine.• and CNet.• Windows 2000 and Windows XP users can freely download the program from Microsoft's web site, and Microsoft has stated that Windows Defender will ship as part of Windows Vista.• Third-party analyses A study conducted by Kevin Mitnick and marketing communications firm Avantgarde found that an unprotected and unpatched Windows XP system lasted only 4 minutes on the Internet before it was 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: See also General Further reading Official Programming Reviews and evaluation High Performance Computing Other | |||||||||||||||||||||||||||||
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