A Little Windows History
As you surely know, Windows is a
operating system (
that is the heart and soul of your computer. Although Windows was once a toy (I remember when people bought Windows
because of the graphical word processor and paint program it included), it's now an essential element in your computing experience.
When Windows first hit the market in 1985, it actually was a shell that sat upon the increasingly shaky foundations of MS-DOS. Early versions were frequently used as menuing systems for launching MS-DOS programs, because programs that actually required Windows were quite
. In fact, to help promote Windows as a platform for programs, Microsoft distributed a "runtime" version of Windows with some of the early Windows-based programs such as Aldus PageMaker (now an Adobe product). Users who didn't have a full version of Windows needed to install the runtime version before using the program. The runtime version of Windows was launched when the application (such as PageMaker) was started and provided Windows menuing and print services, and closed when the application was closed.
Windows didn't really take off until the introduction of Windows 3.0 in 1990 (it could multitask both DOS and Windows programs if you used a 386 or 486 processor) and Windows 3.1 in 1992, which introduced TrueType scalable fonts. Windows for Workgroups 3.1 (1992) and 3.11 (1994) pioneered the built-in networking features that would typify all
versions of Windows up to the present. Windows for Workgroups 3.11 was the last version of Windows to require that MS-DOS or a comparable text-based operating system be present at installation time.
Although Windows 95, Windows 98, and Windows Me no longer required MS-DOS, they still used an improved form of DOS for some operations. This dependence upon MS-DOS made for an increasingly unstable operating system because the management tricks necessary to keep MS-DOS, old 16-bit Windows applications, and new 32-bit Windows programs running on the same hardware at the same time led to frequent reboots and system lockups. Although many of the features pioneered by Windows 9x and Windows Me have been retained and enhanced in Windows XP, Windows XP is not a true
of DOS-based Windows.
Instead, the Windows XP family is the latest descendent of the "other" Windows family, a family of Windows products that do not use MS-DOS as a foundation. Microsoft's development of a nonDOS-based operating system goes back to 1987 and the joint development (with IBM) of a Windows replacement called OS/2. OS/2 was aimed squarely at the emerging corporate network world then dominated by Novell and its NetWare network operating system.
Unlike NetWare, Microsoft and IBM's OS/2 was designed to handle both the server and the desktop side of network computing. Unfortunately for OS/2, the IBM-Microsoft partnership broke up in 1991 after a series of
about the direction of OS/2. IBM kept OS/2, and Microsoft stuck with Windows. Microsoft had already begun the development of Windows NT in October 1988 with the hiring of Dave Cutler, who had developed the VMS (Virtual Memory System) operating system for Digital Equipment's (DEC) line of VAX multitasking and multiuser computers.
The development of Windows NT took several years: The first version to reach retail
, Windows NT 3.1, was introduced in mid-1993. Windows NT introduced several features common to all its successors, including Windows 2000 and Windows XP:
The user doesn't need to wait for one task to finish before starting another one.
Client/server model for computing
The operating system is divided into two
, just as with mainframe systems.
Dynamic disk caching/virtual memory
The operating system can use more than one drive as virtual memory (using disk space in place of RAM); desktop Windows versions up through Windows Me can use only one drive for virtual memory.
Fault tolerance features
The capability to handle power outages and disk crashes.
Capability to start and stop network services without rebooting.
Fully 32-bit architecture
Windows NT and its successors are free from the limitations of 16-bit Windows (and MS-DOS!) instructions.
Support for multiple file systems, including the old FAT16 file system used by MS-DOS and Windows 9x and the NTFS file system developed for Windows NT, which supports advanced security features, long filenames, and automatic error correction.
Windows NT 4.0, introduced in mid-1996, was
after the Windows 95 user interface (instead of the Windows 3.1 user interface used by earlier Windows NT versions), and provided crash protection
to that of Windows 95. However, it lacked support for Plug and Play, the easy hardware installation feature introduced by Windows 95, and many Windows 95-compatible hardware devices wouldn't work with Windows NT 4.0.
Windows 2000, introduced in early 2000, was originally called NT 5.0 during its prerelease period, and
the NT family's move toward becoming more user-friendly. Many of Windows 2000's features have become part of Windows XP Professional, including Plug-and-Play hardware support, ACPI power management, support for USB and IEEE-1394 ports and devices, AGP video, Internet Connection Sharing, and enhanced system management. Windows 2000 also improved drive support by adding support for FAT32, the file system introduced by Windows 95 OSR 2.x that shatters the 2.1GB limit per drive letter imposed by FAT16. It also introduced a more advanced version of NTFS that supports file encryption, file compression, and support for mounting and
to allow them to be accessed through folders on another drive. Windows XP also supports these
features of Windows 2000.
While Windows NT was being developed and improved, Microsoft was also developing its Windows 9x product family, which culminated in the release of Windows Me in 2000. Windows Me, like Windows 9x, is a hybrid operating system with some features inherited from MS-DOS as well as 32-bit code, so its internal architecture is nothing like Windows XP's. Instead, the most significant fact about Windows Me from a Windows XP Professional user's viewpoint is Windows Me's introduction of a wide variety of built-in multimedia and imaging features. Windows XP features, such as the Scanner and Camera Wizard, the slideshow features in the My Pictures folder, and Movie Maker, are all descended from Windows Me. Another significant feature of Windows XP that Windows Me pioneered is System Restore, which allows the user to get around tricky OS problems by resetting the system configuration to what it was on a previous day.
Like Windows 2000 before it, Windows XP is a highly extensible operating system. Windows XP uses a
derived from Windows 2000, featuring an object-oriented, modular design that enables various types of services, file systems, and other subsystems to be attached to the
operating system, just as various types of hardware can be attached to a PC. The result is that Windows XP can emulate other operating systems and support applications originally designed for DOS, 16-bit Windows, older 32-bit Windows versions, and POSIX-compliant UNIX applications. Although Windows 2000 had a subsystem for OS/2, XP does not. Also, whereas Windows 2000 provided a "one-
-fits-all" approach to running older Windows programs, which didn't always work, Windows XP goes beyond Windows 2000 by providing a customizable emulation feature that enables you to select which version of Windows it should emulate to run a particular program. See Chapter 25, "Maintaining and Optimizing System Performance," for details.
Windows XP Professional can be
described as a combination of the security, stability, and corporate networking features of Windows 2000 and the multimedia, entertainment, and error-handling features of Windows Me.