The story of Windows begins with a very different operating system, developed by Microsoft for the first IBM personal computer and referred to as MS-DOS or PC-DOS. The initial version, DOS 1.0, was released in August 1981. It consisted of 4000 lines of assembly language source code and ran in 8 Kbytes of memory using the Intel 8086 microprocessor.
When IBM developed a hard disk-based personal computer, the PC XT, Microsoft developed DOS 2.0, released in 1983. It contained support for the hard disk and provided for hierarchical directories. Heretofore, a disk could contain only one directory of files, supporting a maximum of 64 files. While this was adequate in the era of floppy disks, it was too limited for a hard disk, and the single-directory restriction was too clumsy. This new release allowed directories to contain sub-directories as well as files. The new release also contained a richer set of commands embedded in the operating system to provide functions that had to be performed by external programs provided as utilities with release 1. Among the capabilities added were several UNIX-like features, such as I/O redirection, which is the ability to change the input or output identity for a given application, and background printing. The memory-resident portion grew to 24 Kbytes.
When IBM announced the PC AT in 1984, Microsoft introduced DOS 3.0. The AT contained the Intel 80286 processor, which provided extended addressing and memory protection features. These were not used by DOS. To remain compatible with previous releases, the operating system simply used the 80286 as a "fast 8086." The operating system did provide support for new keyboard and hard disk peripherals. Even so, the memory requirement grew to 36 Kbytes. There were several notable upgrades to the 3.0 release. DOS 3.1, released in 1984, contained support for networking of PCs. The size of the resident portion did not change this was achieved by increasing the amount of the operating system that could be swapped.
DOS 3.3 released in 1987, provided support for the new line of IBM machines, the PS/2. Again, this release did not take advantage of the processor capabilities of the PS/2, provided by the 80286 and the 32-bit 80386 chips. The resident portion at this stage had grown to a minimum of 46 Kbytes, with more required if certain optional extensions were selected. By this time, DOS was being used in an environment far beyond its capabilities. The introduction of the 80486 and then the Intel Pentium chip provided power and features that simply could not be exploited by the simple-minded DOS. Meanwhile, beginning in the early 1980s, Microsoft began development of a graphical user interface (GUI) that would be interposed between the user and DOS. Microsoft's intent was to compete with Macintosh, whose operating system was unsurpassed for ease of use. By 1990, Microsoft had a version of the GUI, known as Windows 3.0, which incorporated some of the user friendly features of Macintosh.However, it was still hamstrung by the need to run on top of DOS.
After an abortive attempt by Microsoft to develop with IBM a next-generation operating system, which would exploit the power of the new microprocessors and which would in corporate the ease-of-use features of Windows, Microsoft struck out on its own and developed a new operating system from the ground up, Windows NT. Windows NT exploits the capabilities of contemporary microprocessors and provides multitasking in a single-user or multiple-user environment.
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Windows NT[/caption]
The first version of Windows NT (3.1) was released in 1993, with the same GUI as
Windows 3.1, another Microsoft operating system (the follow-on to Windows 3.0). However,
NT 3.1 was a new 32-bit operating system with the ability to support older DOS and Windows
applications as well as provide OS/2 support.
After several versions of NT 3.x, Microsoft released NT 4.0. NT 4.0 has essentially the
same internal architecture as 3.x. The most notable external change is that NT 4.0 provides the
same user interface as Windows 95. The major architectural change is that several graphics components that ran in user mode as part of the Win32 subsystem in 3.x have been moved into the Windows NT Executive, which runs in kernel mode. The benefit of this change is to speed up the operation of these important functions. The potential drawback is that these graphics functions now have access to low-level system services, which could impact the reliability of the operating system.
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Windows 2000[/caption]
In 2000, Microsoft introduced the next major upgrade, now called Windows 2000. Again, the underlying Executive and kernel architecture is fundamentally the same as in NT 4.0, but new features have been added. The emphasis in Windows 2000 is the addition of services and functions to support distributed processing. The central element of Windows 2000's new features is Active Directory, which is a distributed directory service able to map names of arbitrary objects to any kind of information about those objects.
One final general point to make about Windows 2000 is the distinction between Windows 2000 Server and Windows 2000 desktop. In essence, the kernel and executive architecture and services remain the same, but Server includes some services required to use as a network server.
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Windows XP[/caption]
In 2001, the latest desktop version of Windows was released, known as Windows XP. Both home PC and business workstation versions of XP are offered. Also in 2001, a 64-bit version of XP was introduced. In 2003, Microsoft introduced a new server version, known as Windows Server 2003 both 32-bit and 64 bit versions are available. The 64-bit versions of XP and Server 2003 are designed specifically for the 64-bit Intel Itanium hardware.
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Windows-Vista[/caption]
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Windows-Vista[/caption]
Microsoft was able to change the look and designed of OS by inventing Windows Vista after XP, It was released in 2006 and was upto 2008. Design plays a big role in Windows Vista, and features such as the taskbar and the borders around windows get a brand new look. Search gets new emphasis and helps people find files on their PCs faster. Windows Vista introduces new editions that each have a different mix of features. It's available in 35 languages. The redesigned Start button makes its first appearance in Windows Vista. Unlikely some problems were risen among the users inorder to solve those problems
Microsoft took initiatives and built a new OS named it Windows 7. It solved all the problems of that Vista users were having, and introduced wireless hotspots, Bitlocker Encryption to secure PC’s and Laptops, Snap, Peek, and Shake—which both improved functionality and made the interface more fun to use.
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Windows 7[/caption]
Microsoft was able to change the look and designed of OS by inventing Windows Vista after XP, It was released in 2006 and was upto 2008. Design plays a big role in Windows Vista, and features such as the taskbar and the borders around windows get a brand new look. Search gets new emphasis and helps people find files on their PCs faster. Windows Vista introduces new editions that each have a different mix of features. It's available in 35 languages. The redesigned Start button makes its first appearance in Windows Vista. Unlikely some problems were risen among the users inorder to solve those problems Microsoft took initiatives and built a new OS named it Windows 7. It solved all the problems of that Vista users were having, and introduced wireless hotspot, Bitlocker Encryption to secure PC’s and Laptops, Snap, Peek, and Shake—which both improved functionality and made the interface more fun to use.
Improvements to the Windows 7 taskbar include live thumbnail previews.
Suddenly Touch-screen smart phones and Tablets took the whole market and Google started builting their own OS called Android as well as planed to take all over the market, and day after day its popularity was increasing. In 2012 Microsoft publishes their own OS Windows 8 mainly builted for Tablet PC but further it was also being used in PC and Laptop. It made user more easy to control their programme in the home screen. It introduces a totally new interface that works smoothly for both touch and mouse and keyboard. Windows 8 also includes enhancements of the familiar Windows desktop, with a new taskbar and streamlined file management.
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Windows 8[/caption]
Along with Windows 8, Microsoft also launched Windows RT, which runs on some
tablets and PCs. Windows RT is designed for sleek devices and long battery life, and
exclusively runs apps from the Windows Store. It also comes with a built-in version of
Office that's optimized for touchscreens.
