The Common Lisp function
software-type
returns a generic name for the Operating System. The Common Lisp function
software-version
returns information about the the version of the Operating System.
In particular
software-type
can be used to distinguish between systems based on Microsoft Windows and those based on Microsoft Windows NT.
software-version
allows you to identify variants such as Windows Millennium Edition, Windows 2000, Windows XP and so on. See the
LispWorks Reference Manual
for details.