Windows – Introduction

Windows – Introduction

Microsoft Windows is the world’s largest operating system for use on personal computers. It is created by Microsoft. There exist also versions of Windows designed for servers. Microsoft first introduced an operating environment named Windows in November,1985, as an add-on to MS-DOS. This was in response to the growing trend of graphical user interface popularised by the Apple Macintosh. Microsoft Windows eventually came to dominate the world personal computer market with market analysts like IDC estimating that Windows has around 90% of the client operating system market

History Of Windows OS
Microsoft has taken two parallel routes in Operating Systems. One route has been the home user and the other has been the professional IT user. The dual route has generally led to the home versions with more "eye candy" and less functionality in networking and security and professional versions with less "eye candy" and better networking and security.

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. In August 1995, Microsoft released Windows 95, which made further changes to the user interface and was the first Windows version to utilize multitasking. In July 1993, Microsoft released Windows NT based on IBM OS/2 technology (which Microsoft had been co-developing for several years prior). NT was considered to be the professional OS. NT and the Windows non-professional line would later be fused together to create Windows XP.

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 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 DOS, Windows allowed users to execute multiple graphical applications at the same time, through co-operative multitasking.

Hybrid 16/32-bit operating environments
Windows 3.0(1990) and Windows 3.1 (1992) perfected the design, notably thanks to virtual memory and loadable virtual device drivers (VxDs) which allowed them to share arbitrary devices between multitasked DOS windows. Most important, 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.

32-bit operating systems
Originally designed and marketed for higher-reliability business use with no DOS heritage. The first release was Windows NT 3.1, 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 if they were 32-bit processors.

The modern 64-bit Windows family comprises Windows XP 64-bit Edition for IA-64 systems,Windows XP Professional x64 Edition for AMD64 systems, and Windows Server 2003, in versions for both IA-64 and AMD64. The AMD64 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.


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