In 1983
Microsoft announced the development of
Windows, a
graphical user interface (GUI)
for its own
operating system (
MS-DOS), which
had shipped for
IBM PC and compatible computers since 1981. Since then, Microsoft has shipped many versions of
Windows, and the product line has changed from a GUI product to a modern
operating system.
The first independent version of Microsoft Windows, version 1.0, released on 20 November 1985, achieved little popularity. It was originally going to be called "Interface Manager" but Rowland Hanson, the head of marketing at
Microsoft, convinced the company that the name <Windows> would be more appealing to consumers. Windows 1.0 was not a complete operating system, but rather an "operating environment" that
extended MS-DOS, and shared the latter's inherent flaws and problems. The first version of Microsoft Windows included a simple
graphics painting program called Windows Paint, Windows Write, a simple word processor, an appointment
"calendar", a "cardfiler", a "Microsoft notepad", a "clock", a " control panel", a "computer terminal", "Clipboard", and RAM driver.
It also included the MS-DOS Executive and a game called Reversi.
Microsoft had worked with Apple Computer to develop several Desk Accessories and other minor pieces of software that were included with early Macintosh system software. As part of the related business negotiations, Microsoft had licensed certain aspects of the Macintosh user interface from
Apple; in later litigation, a district court summarized these aspects as "screen displays". In the development of Windows 1.0, Microsoft intentionally limited its borrowing of certain GUI
elements from the Macintosh user interface, in order to comply with its license.
For example, windows were only displayed "tiled" on the screen; that is, they could not overlap or overlie one another. There was no trash can icon with which to delete files, since Apple claimed
ownership of the rights to that paradigm.
Microsoft Windows version 2 came out on 9 December 1987, and proved slightly more popular than its predecessor. Much of the popularity for Windows 2.0 came by way of its inclusion as a "run-time version" with Microsoft's new graphical applications, Excel and Word for Windows. They could be run from MS-DOS,
executing Windows for the duration of their activity, and closing down Windows upon exit.
Microsoft Windows received a major boost around this time when Aldus PageMaker appeared in a Windows version, having previously run only on Macintosh. Some computer historians date this, the first appearance of a significant and non-Microsoft application for Windows, as the
beginning of the success of Windows.
Versions 2.0x used the real-mode memory model, which confined it to a maximum of 1 megabyte of memory. In
such a configuration, it could run under another multitasker like DESQview, which used the 286 Protected Mode.
Later, two new versions were released: Windows/286 2.1 and Windows/386 2.1. Like previous versions of Windows, Windows/286 2.1 used the real-mode memory model, but was the first version to
support the "High Memory Area|HMA". Windows/386 2.1 had a protected mode kernel with LIM-standard EMS
emulation, the predecessor to XMS which would finally change the topology of IBM PC computing. All Windows and
DOS-based applications at the time were real mode, running over the protected mode kernel by using the virtual 8086 mode,
which was new with the 80386 processor.
Version 2.03, and later 3.0, faced challenges from Apple over its overlapping windows
and other features Apple charged mimicked the ostensibly copyrighted "look and feel" of its operating system and "embodie[d] and generated a copy of the Macintosh" in its OS. Judge William Schwarzer dropped all but 10 of Apple's 189 claims of copyright infringement, and ruled that most of the
remaining 10 were over uncopyrightable ideas.
Microsoft Windows scored a significant success with Windows 3.0, released in 1990. In addition to improved capabilities given to native applications, Windows also allowed users to better
multitask older MS-DOS based software compared to Windows/386, thanks to the introduction of
virtual memory.
Windows 3.0's user interface was finally a serious competitor to the user interface of the Macintosh computer. PCs had
improved graphics by this time, due to VGA video cards, and the Protected/Enhanced mode allowed Windows applications
to use more memory in a more painless manner than their DOS counterparts could. Windows 3.0 could run in Real, Standard,
or 386 Enhanced modes, and was compatible with any Intel processor from the 8086/8088 up to the 80286 and 80386. This was the first version to run Windows programs in protected mode, although the 386 enhanced mode kernel was an enhanced version of the protected mode kernel in Windows/386.
A "multimedia" version, Windows 3.0 with Multimedia Extensions 1.0, was released several months later. This was bundled with "multimedia upgrade kits", comprising a CD-ROM drive and a sound card, such as the Creative Labs Sound Blaster Pro. This version was the precursor to the multimedia features available in Windows 3.1 and later, and was part of Microsoft's specification for the Multimedia PC.
The features listed above and growing market support from application software developers made Windows 3.0 wildly successful, selling around 10 million copies in the two years before the release
of version 3.1. Windows 3.0 became a major source of income for Microsoft, and led the company to revise some of its earlier plans.
During the mid to late 1980s, Microsoft and IBM had cooperatively been developing OS/2 as a successor to DOS. OS/2 would take full advantage of the aforementioned Protected Mode of the Intel 80286 processor and up to 16MB of memory. OS/2 1.0, released in 1987, supported swapping and multitasking and allowed running of DOS executables.
A GUI, called the Presentation Manager (PM), was not available with OS/2 until version 1.1,
released in 1988. Its API was incompatible with Windows. (Among other
things, Presentation Manager placed X,Y coordinate 0,0 at the bottom left of the screen like Cartesian coordinates, while Windows put 0,0 at the top left of the screen like most other computer window systems.) Version 1.2,
released in 1989, introduced a new file system, HPFS, to replace the FAT file
system.
By the early 1990s, conflicts developed in the Microsoft/IBM relationship. They cooperated with each other in developing their PC operating systems, and had access to each others' code. Microsoft
wanted to further develop Windows, while IBM desired for future work to be based on OS/2. In an attempt to resolve this tension, IBM and Microsoft agreed that IBM would develop OS/2 2.0, to
replace OS/2 1.3 and Windows 3.0, while Microsoft would develop a new operating system, OS/2 3.0, to later succeed OS/2 2.0.
This agreement soon however fell apart, and the Microsoft/IBM relationship was terminated. IBM continued to develop OS/2, while Microsoft changed the name of its (as yet unreleased) OS/2 3.0 to
Windows NT. Both retained the rights to use OS/2 and Windows technology developed up to the termination of the agreement;
Windows NT, however, was to be written anew, mostly independently (see below).
After an interim 1.3 version to fix up many remaining problems with the 1.x series, IBM released OS/2 version 2.0 in 1992. This was a major improvement: it featured a new, object-oriented GUI,
the Workplace Shell (WPS), that included a desktop and was considered by many to be OS/2's best feature. Microsoft would later imitate much of it in Windows 95. Version 2.0 also provided a full
32-bit API, offered smooth multitasking and could take advantage of the 4 gigabytes of address space provided by the Intel
80386. Still, much of the system still had 16-bit code internally which required, among other things, device drivers to be 16-bit code as well. This was one of the reasons for the chronic
shortage of OS/2 drivers for the latest devices. Version 2.0 could also run DOS and Windows 3.0 programs, since IBM had retained the right to use the DOS and Windows code as a result of the
breakup.
n response to the impending release of OS/2 2.0, Microsoft developed Windows 3.1, which includes several
minor improvements to Windows 3.0 (such as display of TrueType scalable fonts, developed jointly with Apple), but primarily
consists of bugfixes and multimedia support. It also excludes support for Real mode, and only runs on an 80286
or better processor. Later Microsoft also released Windows 3.11, a touch-up to Windows 3.1 which includes all of the patches and updates that followed the release of Windows 3.1 in 1992. Around
the same time, Microsoft released Windows for Workgroups (WfW), available both as an add-on for existing Windows 3.1 installations and in a version that included the base Windows environment and
the networking extensions all in one package. Windows for Workgroups includes improved network drivers and protocol stacks, and support for peer-to-peer networking. One optional download for WfW
was the "Wolverine" TCP/IP protocol stack, which allowed for easy access to the Internet through corporate networks. There are two versions of Windows for Workgroups, WfW 3.1 and WfW 3.11. Unlike
the previous versions, Windows for Workgroups 3.11 only runs in 386 Enhanced mode, and requires at least an 80386SX processor.
All these versions continued version 3.0's impressive sales pace. Even though the 3.1x series still lacked most of the important features of OS/2, such as long file names, a desktop, or
protection of the system against misbehaving applications, Microsoft quickly took over the OS and GUI markets for the IBM PC. The Windows API became the de-facto standard for consumer software.
Meanwhile Microsoft continued to develop Windows NT. The main architect of the system was Dave Cutler, one of the chief
architects of VMS at Digital Equipment Corporation (later purchased by Compaq, now
part of Hewlett-Packard). Microsoft hired him in August 1988 to create a successor to OS/2, but Cutler created a completely new
system instead. Cutler had been developing a follow-on to VMS at DEC called Mica, and when DEC dropped the project he brought the expertise and around 20
engineers with him to Microsoft. DEC also believed he brought Mica's code to Microsoft and sued. Microsoft eventually paid $150 million U.S. and agreed to support DEC's Alpha CPU chip in NT.
Windows NT 3.1 (Microsoft marketing wanted Windows NT to appear to be a continuation of Windows 3.1) arrived in Beta form to developers at the July 1992 Professional Developers Conference in San Francisco. Microsoft
announced at the conference its intentions to develop a successor to both Windows NT and Windows 3.1's replacement (code-named Chicago), which would unify the two into one operating system. This
successor was codenamed Cairo. In hindsight, Cairo was a much more difficult project than
Microsoft had anticipated and, as a result, NT and Chicago would not be unified until Windows XP. Parts of Cairo have
still not made it into Windows as of 2009 - specifically, the WinFS file system, which was the much touted Object File System of
Cairo. Microsoft announced that they have discontinued the separate release of WinFS for Windows XP and Windows Vista and will gradually incorporate the technologies developed for WinFS in other products and technologies, notably Microsoft SQL Server.
Driver support was lacking due to the increased programming difficulty in dealing with NT's superior hardware abstraction model. This problem plagued the NT line all the way through Windows 2000.
Programmers complained that it was too hard to write drivers for NT, and hardware developers were not going to go through the trouble of developing drivers for a small segment of the market.
Additionally, although allowing for good performance and fuller exploitation of system resources, it was also resource-intensive on limited hardware, and thus was only suitable for larger, more
expensive machines.
However, these same features made Windows NT perfect for the LAN server market (which in 1993 was
experiencing a rapid boom, as office networking was becoming common). NT also had advanced network connectivity options and the efficient NTFS file system. Windows NT version 3.51 was Microsoft's entry into this field, and took away market share from Novell (the dominant player) in the
following years.
One of Microsoft's biggest advances initially developed for Windows NT was a new 32-bit API, to replace the legacy 16-bit Windows API. This API was called Win32, and from then on
Microsoft referred to the older 16-bit API as Win16. The Win32 API had three main implementations: one for
Windows NT, one for Win32s (which was a subset of Win32 which could be used on Windows 3.1 systems), and one for Chicago. Thus
Microsoft sought to ensure some degree of compatibility between the Chicago design and Windows NT, even though the two systems had radically different internal architectures. Windows NT was the
first Windows operating system based on a hybrid kernel.
After Windows 3.11, Microsoft began to develop a new consumer oriented version of the operating system code-named
Chicago. Chicago was designed to have support for 32-bit preemptive multitasking like OS/2 and Windows NT, although a 16-bit kernel would remain for the sake of backward compatibility. The Win32
API first introduced with Windows NT was adopted as the standard 32-bit
programming interface, with Win16 compatibility being preserved through a technique known as "thunking". A
new GUI was not originally planned as part of the release, although elements of the Cairo user interface were borrowed and added as other aspects of the release (notably Plug and Play) slipped.
Microsoft did not change all of the Windows code to 32-bit; parts of it remained 16-bit (albeit not directly using real
mode) for reasons of compatibility, performance and development time. Additionally it was necessary to carry over design decisions from earlier versions of Windows for reasons of backwards
compatibility, even if these design decisions no longer matched a more modern computing environment. These factors eventually began to impact the operating system's efficiency and stability.
Microsoft marketing adopted Windows 95 as the product name for Chicago when it was released on August 24, 1995. Microsoft
had a double gain from its release: first it made it impossible for consumers to run Windows 95 on a cheaper, non-Microsoft DOS; secondly, although traces of DOS were never completely removed
from the system, and a version of DOS would be loaded briefly as a part of the booting process, Windows 95 applications ran
solely in 386 Enhanced Mode, with a flat 32-bit address space and virtual memory. These features make it possible
for Win32 applications to address up to 2 gigabytes of virtual RAM (with another 2GB reserved for the operating system), and
in theory prevented them from inadvertently corrupting the memory space of other Win32 applications. In this respect the functionality of Windows 95 moved closer to Windows NT, although Windows 95/98/ME did not support more than 512 megabytes of
physical RAM without obscure system tweaks.
IBM continued to market OS/2, producing later versions in OS/2 3.0 and 4.0 (also called Warp). Responding to complaints about OS/2 2.0's
high demands on computer hardware, version 3.0 was significantly optimized both for speed and size. Before Windows 95 was released, OS/2 Warp 3.0 was even shipped preinstalled with several large
German hardware vendor chains. However, with the release of Windows 95, OS/2 began to lose market share.
It is probably impossible to choose one specific reason why OS/2 failed to gain much market share. While OS/2 continued to run Windows 3.1 applications, it lacked support for anything but the
Win32s subset of Win32 API (see above). Unlike with Windows 3.1, IBM did not have access to the source code for Windows 95 and was
unwilling to commit the time and resources to emulate the moving target of the Win32 API. IBM also introduced OS/2 into the United States v. Microsoft case, blaming unfair marketing tactics on Microsoft's part, but many people would probably agree that
IBM's own marketing problems and lack of support for developers contributed at least as much to the failure.[original research?]
Microsoft went on to release five different versions of Windows 95:
- Windows 95 - original release
- Windows 95 A - included Windows 95 OSR1 slipstreamed into the installation.
- Windows 95 B - (OSR2) included several major enhancements, Internet Explorer (IE) 3.0 and full
FAT32 file system support.
- Windows 95 B USB - (OSR2.1) included basic USB support.
- Windows 95 C - (OSR2.5) included all the above features, plus IE 4.0. This was the last 95 version produced.
OSR2, OSR2.1, and OSR2.5 were not released to the general public, rather, they were available only to OEMs that would preload the OS onto computers. Some companies sold new hard drives with OSR2 preinstalled (officially justifying
this as needed due to the hard drive's capacity).
The first Microsoft Plus! add-on pack was sold for Windows 95.
Microsoft released Windows NT 4.0, which features the new Windows 95 interface on top of the Windows NT kernel. (a patch was available for developers to make NT 3.51 use the new UI, but it was
quite buggy).
Windows NT 4.0 came in four versions:
- Windows NT 4.0 Workstation
- Windows NT 4.0 Server
- Windows NT 4.0 Server, Enterprise Edition (includes support for 8-way SMP and
clustering)
- Windows NT 4.0 Terminal Server
On 25 June 1998, Microsoft released Windows 98, which was widely regarded as a minor revision of Windows 95, but generally found to be more stable and reliable than its 1995 predecessor. It
included new hardware drivers and better support for the FAT32 file system which allows support for
disk partitions larger than the 2 GB maximum accepted by Windows 95. The USB support in Windows 98 is far superior
to the token, unreliable support provided by the OEM editions of Windows 95. It
also controversially integrated the Internet Explorer browser into the Windows GUI and Windows Explorer file
manager, prompting the opening of the United States v. Microsoft case, dealing with the
question of whether Microsoft was abusing its hold on the PC operating system market to unfairly compete with companies such as Netscape.
In 1999, Microsoft released Windows 98 Second Edition, an interim release whose most notable feature was the addition of Internet Connection Sharing, which was a form of network address translation, allowing several machines on a LAN (Local Area Network) to share a single Internet connection. Hardware support through device drivers was increased. Many minor problems present in the
original Windows 98 were found and fixed which make it, according to many, the most stable release of Windows 9x family.
Microsoft released Windows 2000, known during its development cycle as Windows NT 5.0, in February 2000. It was successfully deployed both on the server and the workstation markets. Amongst
Windows 2000's most significant new features was Active Directory, a near-complete replacement of the NT 4.0
Windows Server domain model, which built on industry-standard technologies like DNS, LDAP, and Kerberos to
connect machines to one another. Terminal Services, previously only available as a
separate edition of NT 4, was expanded to all server versions. A number of features from Windows 98 were incorporated as well, such as an improved Device Manager, Windows Media Player, and a revised DirectX that made it possible
for the first time for many modern games to work on the NT kernel. Windows 2000 is also the last NT-kernel Windows operating system to lack Product Activation.
While Windows 2000 upgrades were available for Windows 95 and Windows 98, it was not intended for home users. It lacked device drivers for many common consumer devices such as scanners and printers.
Windows 2000 was available in six editions:
- Windows 2000 Professional
- Windows 2000 Server
- Windows 2000 Advanced Server
- Windows 2000 Datacenter Server
- Windows 2000 Advanced Server Limited Edition
- Windows 2000 Datacenter Server Limited Edition
n September 2000, Microsoft introduced Windows Me (Millennium Edition), which upgraded Windows 98 with enhanced multimedia and Internet features. It also introduced the first version of
System Restore, which allowed users to revert their system state to a previous "known-good" point in the case of system failure. System Restore was a notable feature that made its way into
Windows XP. The first version of
Windows Movie Maker was introduced as well.
Windows Me was conceived as a quick one-year project that served as a stopgap release between Windows 98 and Windows XP. Many of the new features were available from the Windows Update site as updates for older Windows versions, (System Restore and Windows Movie Maker were exceptions). As a
result, Windows Me was not acknowledged as a unique Operating System along the lines of 95 or 98. Windows Me was widely criticised for serious stability issues, and for lacking real mode DOS support, to the point of being referred to as the "Mistake Edition" or Me meaning "Many Errors". Windows Me was the
last operating system to be based on the Windows 9x (monolithic) kernel and MS-DOS. It is also the last 32-bit release of Microsoft Windows which does not include Product Activation.
n 2001, Microsoft introduced Windows XP (code named "Whistler"). The merging of the
Windows NT/2000 and Windows 95/98/Me lines was finally achieved with Windows XP. Windows XP uses the Windows NT 5.1 kernel, marking the entrance of the Windows NT core to the consumer market, to replace the aging 16/32-bit branch. The initial release
met with considerable criticism, particularly in the area of security, leading to the release of three major Service Packs. Windows XP SP1 was released in September of 2002, SP2 came out in August, 2004 and SP3 came out in April, 2008. Service Pack 2
provided significant improvements and encouraged widespread adoption of XP among both home and business users. Windows XP lasted longer than any other version of Windows, from 2001 to 2007 when
Windows Vista was released to consumers. The Windows XP line of operating systems was succeeded by Windows Vista on
30 January 2007.
Windows XP is available in a number of versions:
-
Windows XP Home Edition, for home desktops and laptops (notebooks)
-
Windows XP Professional, for business and power users
- Windows XP Professional N, as above, but without a default installation of Windows Media Player, as mandated by a European Union ruling
-
Windows XP Media Center Edition (MCE), released in
November 2002 for desktops and notebooks with an emphasis on home entertainment
- Windows XP Media Center Edition 2003
- Windows XP Media Center Edition 2004
- Windows XP Media Center Edition 2005, released on 12 October 2004.
-
Windows XP Tablet PC Edition, for tablet PCs (PCs with touch screens)
- Windows XP Tablet PC Edition 2005
-
Windows XP Embedded, for embedded systems
-
Windows XP Starter Edition, for new computer users in developing
countries
-
Windows XP Professional x64 Edition, released on
25 April 2005 for home and workstation systems utilizing 64-bit processors based on the x86-64 instruction set developed by AMD
as AMD64; Intel calls their version Intel 64
-
Windows XP 64-bit Edition, is a version for Intel's Itanium line of processors; maintains 32-bit compatibility solely through a software emulator. It is roughly analogous to Windows XP Professional
in features. It was discontinued in September 2005 when the last vendor of Itanium workstations stopped shipping Itanium systems marketed as "Workstations".
- Windows XP 64-bit Edition 2003, based on the Windows NT 5.2 codebase.
On 24 April 2003 Microsoft launched Windows Server 2003, a notable update to Windows
2000 Server encompassing many new security features, a new "Manage Your Server" wizard that simplifies configuring a machine for specific roles, and improved performance. It has the version number NT 5.2. A few services not
essential for server environments are disabled by default for stability reasons, most noticeable are the "Windows Audio" and "Themes" services; Users have to enable them manually to get sound or
the "Luna" look as per Windows XP. The hardware acceleration for display is also turned off by default, users have to turn the
acceleration level up themselves if they trust the display card driver.
December 2005, Microsoft released Windows Server 2003 R2, which is actually Windows Server 2003 with SP1 (Service Pack 1) plus an add-on package. Among the new features are a number of management features for branch offices, file serving, printing and company-wide identity integration.
Windows Server 2003 is available in six editions:
- Web Edition (32-bit)
- Standard Edition (32 and 64-bit)
- Enterprise Edition (32 and 64-bit)
- Datacenter Edition (32 and 64-bit)
- Small Business Server (32 and 64-bit)
- Storage Server (OEM channel only)
In July 2006, Microsoft released a
thin-client version of Windows XP Service Pack 2, called
Windows Fundamentals for Legacy PCs (WinFLP). It is only available to
Software Assurance customers. The aim of WinFLP is to give companies a viable upgrade
option for older PCs that are running Windows 95, 98, and Me that will be supported with patches and updates for the next several years. Most user applications will typically be run on a remote
machine using Terminal Services or
Citrix.
Windows Home Server (codenamed Q, Quattro) is a server product based on Windows Server 2003, designed
for consumer use. The system was announced on January 7th, 2007 by Bill Gates. Windows Home Server can be configured and
monitored using a console program that can be installed on a client PC. Such features as Media Sharing, local and remote drive backup and file duplication are all listed as features.
The current client version of Windows, Windows Vista (codenamed Longhorn) was released on 30 November 2006 to
business customers, with consumer versions following on 30 January 2007. Windows Vista intended to have enhanced security by introducing a new restricted user mode called User Account Control, replacing the "administrator-by-default" philosophy of Windows XP. Vista also features
new graphics features, the Windows Aero GUI, new applications (such as Windows Calendar, Windows DVD Maker and
some new games including Chess, Mahjong, and Purble Place), a revised and more secure version of Internet Explorer, a new version of Windows Media
Player, and a large number of underlying architectural changes.
Windows Vista ships in several editions:
- Starter (only available in developing countries)
- Home Basic
- Home Premium
- Business
- Enterprise (only available to large businesses and enterprises)
- Ultimate (combines both Home Premium and Enterprise)
All editions (except Starter edition) are currently available in both 32-bit and 64-bit versions. The biggest advantage of the 64-bit version is breaking the 4 gigabyte memory barrier, which
32-bit computers cannot fully access. In the first year after Vista's release, most installations were still 32-bit, due to poor driver support of the 64-bit version.
Windows Server 2008, released on 27 February 2008, was originally known as Windows Server Codename "Longhorn". Windows Server 2008 builds on the technological and security advances first
introduced with Windows Vista, and is significantly more modular than its predecessor, Windows Server 2003. At the Professional Developers Conference (PDC) 2008, Microsoft announced Windows Server 2008 R2, as the server variant of Windows 7.
Windows Server 2008 R2 will ship in 64-bit (x64 and Itanium)
only.
Windows Server 2008 is available in ten editions:
- Windows Server 2008 Standard Edition (32-bit and 64-bit)
- Windows Server 2008 Enterprise Edition (32-bit and 64-bit)
- Windows Server 2008 Datacenter Edition (32-bit and 64-bit)
- Windows HPC Server 2008
- Windows Web Server 2008 (32-bit and 64-bit)
- Windows Storage Server 2008 (32-bit and 64-bit)
- Windows Small Business Server 2008 (32-bit and 64-bit)
- Windows Essential Business Server 2008 (32-bit and 64-bit)
- Windows Server 2008 for Itanium-based Systems
- Windows Server 2008 Foundation Server
Windows 7 is the next major release after Windows Vista and is planned for a three-year development timeframe. It was previously known by the code-names Blackcomb and Vienna.
Some features of Windows 7 are faster boot-up, Device Stage, Windows PowerShell, less obtrusive User
Account Control, multi-touch, improved window management, homegroup networking, multiple thumbnails for combined taskbar buttons, and better power management for notebooks. Features included with
Windows Vista and not in the Windows 7 Release Candidate include the sidebar (although gadgets remain) and several programs that were removed in favor of downloading their Windows Live counterparts.
On February 3rd, 2009, Microsoft announced that Windows 7 would ship in six editions:
- Starter (available worldwide with new PCs only)
- Home Basic (only available to emerging markets)
- Home Premium
- Professional
- Enterprise (only available to volume-license business customers only)
- Ultimate (available to retail market with limited availability to OEMs)
Microsoft will focus on selling Windows 7 Home Premium and Professional. All editions, except the Starter edition, will be available in both 32-bit and 64-bit versions. According to Paul
Thurrott, news editor for Windows IT Pro Magazine, Microsoft plans to ship Windows 7 in 2009.
Product progression
MS-DOS
Windows (MS-DOS Based)
Windows NT
