UNIX was the first multi-user, multiprocessor, multitasking operating system available for use on PCs. In many ways, UNIX served as the model for other PC operating systems.
DOS is a single-user OS that supports only 640 KB of memory. It features a command-line interface and does not support multitasking or multiprocessing.
The Macintosh operating system supports the graphical nature of the Macintosh computer. The Mac OS brought the first truly graphical user interface to consumers. It also brought interface conformity to the desktop.
Windows 3.0, 3.1, and 3.11 brought a graphical user interface and multitasking capabilities to PCs that ran DOS. Windows 3.x is an operating environment.
IBM's OS/2 Warp was the first true GUI-based operating system for Intel-based PCs. OS/2 is a multitasking operating system that provides support for networking and multiple users.
Microsoft's Windows NT was originally meant as a replacement for DOS but was too resource-intensive to work on most PCs at the time of its release. Microsoft issued two versions-Windows NT Workstation and Windows NT Server.
Windows 95 was Microsoft's first true GUI-based, 32-bit operating system for Intel PCs. Its strengths include multitasking and the capability to run older DOS and Windows 3.x programs.
The features of Windows 98 include advanced Internet capabilities, an improved user interface, and enhanced file system performance, among others.
Linux is a version of UNIX and is available free or at a low cost from various sources. Despite its low cost, it is a powerful 32-bit OS that supports multitasking, multiple users, networking, and almost any application.
Windows 2000 includes the same interface and features of Windows 98, with the file system, networking, power, and stability of Windows NT. Several versions of Windows 2000 are available, each targeting a specific user or computing environment.
Windows XP is a line of operating systems developed by Microsoft for use on general-purpose computer systems, including home and business desktops, notebook computers, and media centers.The letters "XP" stand for experience. Windows XP is the successor to Windows 2000 and is the first consumer-oriented operating system produced by Microsoft to be built on the Windows NT kernel and architecture. Windows XP was first released in October 2001. The most common editions of the operating system are Windows XP Home Edition, which is targeted at home users, and Windows XP Professional, which has additional features, such as support for Windows Server domains and dual processors, and is targeted at power users and business clients. Windows XP Media Center Edition consists of Windows XP Professional with new features enhancing the ability to record and watch TV shows, watch DVDs, listen to music and more. Windows XP Tablet PC Edition is designed to run the ink-aware Tablet PC platform. Two separate 64-bit versions of Windows XP were also released, Windows XP 64-bit Edition for IA-64 (Itanium) processors and Windows XP Professional x64 Edition for AMD64/EM64T processors. Windows XP is known for its improved stability and efficiency over previous versions of Windows. It presents a significantly redesigned graphical user interface (GUI), a change Microsoft promoted as more user-friendly than previous versions of Windows. New software management capabilities were introduced to avoid the "DLL hell" that plagued older consumer versions of Windows. It is also the first version of Windows to use product activation to combat software piracy, a restriction that did not sit well with some users and privacy advocates. Windows XP has also been criticized by some users for security vulnerabilities, tight integration of applications such as Internet Explorer and Windows Media Player, and for aspects of its user interface.
Windows Vista is scheduled to be the next major revision of Microsoft Windows, with a planned release date of November 2006 for business editions, and January 2007 for other editions.