Windows 7 is released but its version is called 6.1 instead of 7. Well, the reason behind this is experience.

The last major version change was when Vista came out. The major version changed from 5 to 6 and thus many application stopped working. The reason is simply an incorrect implementation

if (MajorVersion >= 5) and (MinorVersion >= 1) then

These are the results:

MajorVersion MinorVersion Condition Result
… … …
4 1 False
4 2 False
4 3 False
5 0 False
5 1 True
5 2 True
5 3 True
6 0 False
6 1 True
7 0 False
7 1 True

As you can see this code works for Windows XP (5.x) but no more for Vista without SP (6.x). MS didn’t want to repeat history for Windows 7 (or didn’t want to release a Windows 7 SP1) and just refused to increase the major version.

Please go and check your version checking implementations again so your apps won’t refuse to run on Windows 8 or 9 or 10…

//from SysUtils
function CheckWin32Version(AMajor: Integer; AMinor: Integer = 0): Boolean;
begin
 Result := (Win32MajorVersion > AMajor) or
 ((Win32MajorVersion = AMajor) and
 (Win32MinorVersion >= AMinor));
end;

Related

Version Checking for Delphi