Microsoft Windows: Difference between revisions

Revision as of 16:11, 22 July 2005

Revision as of 16:12, 22 July 2005

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* '''Hybrid 16/32-bit operating environments'''. ''Windows/386'' introduced a 32-bit [[protected mode]] [[kernel (computer science)|kernel]] and [[virtual machine]] monitor. For the duration of a Windows session, it provided a device virtualization for the disk [[controller]], video card, keyboard, mouse, timer and [[interrupt]] controller. 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.x|Windows 3.0]] (1990) and Windows 3.1 (1992) perfected the design, notably thanks to [[virtual memory]] and loadable virtual device drivers ([[VxD]]s) 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 programming language|C]] into [[Assembly_language|assembly]], making this release faster and less memory-hungry than its predecessors.

* '''Hybrid 16/32-bit operating system'''. 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 (computing)|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 however the possibility of running 32-bit multi-threaded preemptively multitasked graphical programs. 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 [[File Allocation Table|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). This was an evolutionary enhancement, in much the same relation to Windows 98 as Windows 3.1 had been to 3.0. In 2000, Microsoft released [[Windows Me]], 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. Compared to previous upgrades, comparatively few people bothered to switch to ME: by this time most power users had already jumped over to the NT family. This can be defended by the fact that Microsoft left little time for Windows Millennium to become popular before announcing their next version of Windows.

* '''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 (1993, numbered "3.1" to match the Windows version and to 1-up [[OS/2]] 2.1, its main competitor at the time), which was followed by NT 3.5 (1994), NT 3.51 (1995), and NT 4.0 (1996); the latter of which introduced the Windows 95 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, [[Microsoft codenames|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]]. XP finally rendered DOS obsolete, and since then a new business system, [[Windows Server 2003]], has expanded the top end of the range, and the forthcoming [[Windows Longhorn]] will complete it. [[Windows CE]], Microsoft's offering in the mobile and embedded markets, is also a true 32-bit operating system.