There are several reasons for this. "Some of the new components of the Payment Software product line, the User Manager application and encryption subsystem, are based on technologies that may not work on older versions of Windows. " Microsoft designed these products for home rather than commercial use, meaning they do not have the same security features as the operating systems we do support. This means that it may be substantially more difficult for a merchant to pass a security audit while using one of these operating systems." Microsoft is in the process of withdrawing support for these operating systems.