Microsoft Windows Versions

An operating system (OS) is not just any program on your computer. Rather, the operating system is the primary program that controls your computer and allows you to run other programs. Without an operating system, your computer wouldn't do anything useful. None of the other programs you use would work without an operating system. There are a number of operating systems available, but you generally only need one of them — at least, only one at any given time. Within your operating system, you may have any number of application programs installed, however, and you may use several of them at once.

Microsoft, based in Redmond, Washington, is a very large company, responsible for a large number of different products, including several operating systems. Historically, Microsoft's operating systems fell into two basic categories, which correspond to the left and right columns of the chart below. (There is a third category of Microsoft OS, called Windows CE, but it is designed for special devices, not for regular computers, and this handout does not discuss it further.) Today, only the OS in the left-hand column is still produced.

In order to talk about the versions of Windows, we need to talk breifly about two earlier operating systems: Unix, and CP/M. Unix was developed at Bell Labs for use in the telecommunications industry. CP/M was developed at DRI for use on smaller computers that individual research technicians might have. (Smaller is a relative term; this was before the time of microcomputers.) You don't need to know very much about Unix and CP/M. What's important is that they were different and were designed for different purposes.

This leads us to two of the earliest Microsoft operating systems, XENIX and DOS. XENIX was made to be a lot like Unix, and DOS was more like CP/M. DOS was marketed with the IBM PC starting around 1980, and became the most popular operating system for home computers. XENIX was not designed for home computers, but was used in more technical, business-type, network environments. This leaves you wondering what either of these has to do with Windows...

The first versions of Windows were not really operating systems as such; Windows 2.0 and later Windows 3.0 and 3.1 and 3.11 were graphical user environments. At that time, many operating systems (including XENIX and DOS) required the user to type commands at the keyboard in order to get the computer to do anything. Windows was a program that was designed to run on top of an existing operating system and let the user run programs by clicking with the mouse. Many people bought computers equipped with DOS and Windows 3.1. Often they never learned to use DOS except to get Windows started, which they used to run all their programs.

Around 1993 or 1994, Microsoft decided that if people were going to be running programs using Windows, by clicking with a mouse, it was silly to have to run Windows overtop of a command-line operating system like DOS. So Microsoft began merging the Windows user interface with their operating systems. They merged it with their experimental system called NT (which was based conceptually on XENIX and some other things) and called the result Windows NT. Windows NT 3.5 came out around 1994. They also merged Windows with DOS and produced another operating system, which they called Windows 95, because of the year it was originally scheduled to be released. Windows NT was marketed toward businesses that needed to provide network services, and Windows 95 was marketed toward home users and office desktops. Microsoft designed both Windows NT and Windows 95 so that most programs written for one would run on the other. Only programs that needed to do technical things had to be made separate for each, because of the internal differences.

Microsoft continued to produce new versions of both these operating systems. Windows NT 3.5 gave birth to Windows NT 4.0, and Windows 95 became Windows 95 OSR2 and then Windows 98. So far, so good, but now it gets confusing, because the internet changed Microsoft's plans.

NT was designed for networks in the first place, so making it support the internet was relatively easy. DOS, however, wasn't designed for networks, so making Windows 95 and 98 support the internet was more work. After the release of Windows 98, Microsoft realised that the DOS-oriented consumer product line (Windows 95, 95 OSR2, 98) was becomming difficult to maintain and produce new versions, because of some of the ways it worked internally, and because of changes that resulted from the popularity of the internet. (The exact details are quite technical, but they are also not important.) At the same time, Windows NT was maturing, becomming stable, and getting to be easier to use.

So Microsoft announced that they would create a new version, based on Windows NT, that would be marketed toward not just businesses but home users as well. This was originally developed as Windows NT 5.0, but was eventually renamed Windows 2000.

Meanwhile, because NT 5 took longer than expected to be ready, Microsoft packaged a few updates with Windows 98 and re-released it as Windows 98 Second Edition (SE).

In 2000, NT 5 was ready to ship, and Microsoft's marketing department renamed it Windows 2000, hoping everyone would accept it as the next version after Windows 98. The problem was, consumers didn't buy it. They kept on using Windows 98 SE.

In order to pacify computer vendors who wanted to sell computers with a new operating system but didn't want to go with Windows 2000, Microsoft added a few more features to Windows 98 SE and released it again as the Millennium Edition, Windows Me. Windows Me is the last version of the consumer operating system line that started with Windows 95. Microsoft didn't spend a lot of effort marketing it, and it flopped. People kept using Windows 98 SE.

Microsoft investigated some of the reasons people had rejected Windows 2000 for home use, beefed up the user interface, included some additional updates, rolled out a marketing campaign about the Windows Experience, and came out with Windows XP. Home users bought it, and computer vendors started pre-installing it on systems marketed for home users, so Microsoft could finally move everyone over to the NT product line and drop the old consumer line. After this, there were no new versions of the Windows 95 product line. All new versions of Windows now are based on Windows NT.

Microsoft produced an updates for Windows XP, called service packs. With the service packs Windows XP is more secure than the original release, but it looks and feels much the same.

The next major really new version, with new features and a new look and feel, is Windows Vista. Windows Vista was a pretty major change from Windows XP, and at the time it got a lot of bad publicity.

Two and a half years later, the next version came out, called Windows Seven. At the time of this writing (2010), Windows Seven is the latest version.

To further complicate matters, Microsoft sells one version of Windows NT for ordinary desktop computers and another version for servers:

In fact there are at least eight versions each of Vista and Seven, with five being important in the USA: Home Basic, Home Premium, Business/Professional, Enterprise, and Ultimate. Additionally, Windows XP is still available through a downgrade option. If you are now thoroughly confused, it's little wonder.