Win9x

• Windows 95
• Windows 98
• Windows ME.

  Collectively, these operating systems are called either Win9x or Windows-class.

Windows NT

• Windows NT 3.1
• Windows NT 3.5
• Windows NT 3.51
• Windows NT 4.0
• Windows 2000
• Windows XP
• Windows Server 2003 & R2
• Windows Vista
• Windows Server 2008 & R2
• Windows Server 2012 & R2

  Although Microsoft has changed the names of these products for marketing reasons, they are all NT-class operating systems underneath. Windows 2000 is really NT 5.0, and XP is NT 5.1, Vista/2008 are 6.x and so forth. You can verify this by using the GetVersionEx() API call, or looking at the version that's displayed when you start a command prompt.

  NT 3.51 was the first stable and useful version of NT, and was for many years considered the baseline for NT-class machines. There is very little software available for versions of NT prior to 3.51. Each new version of NT has additional features as well as a new name, but typically the platforms are backward-compatible. Therefore, software that runs on NT 3.51 will almost always run on later versions.

  Unfortunately, the reverse is not always true. Since newer versions of the OS have new features, software that uses those new features probably won't run on earlier versions. Because of the shell extensions introduced with NT 4, and, more recently, changes to compiler libraries for 64-bit compatibility, it is difficult to continue to compile for older NT versions. Newer builds of our software will therefore tend to run only on XP and above unless otherwise indicated. Regardless, the versions of Windows any particular program supports will be clearly indicated in the software requirements for the product.

Alpha processor architecture

64-Bit Operating Systems

• Windows Server 2003 & R2
• Windows Vista
• Windows Server 2008 & R2
• Windows Server 2012 & R2

  There are two major hardware platforms for running 64-bit Windows: x64 (also known as AMD64 or Intel EM64T depending on which processor manufacturer is talking) or the IA64 (Intel Itanium) platform. x64 systems are much more common than IA64 systems, so when we speak of 64-bit software, we mean the x64 flavor unless we specify otherwise.

  Software compiled specifically to run on these 64-bit platforms is not compatible with the 32-bit versions of Windows. However, most 32-bit programs will run on a 64-bit OS. This means that even if a 64-bit version of a particular program isn't available, you can still run the 32-bit version on your 64-bit OS just fine.

  In general, we offer both 32-bit and 64-bit versions of our newer software, however some older software may only be available in 32-bit. Therefore, you should assume our software is 32-bit unless we tell you a 64-bit version is also available.