Interrupt 2Fh Function 1600h

mov     ax, 1600h   ; Get Windows Installed State
int     2Fh         ; multiplex interrupt

test    al, 7Fh
jz      No_EM_Win   ; Windows not running

Get Installed State (Interrupt 2Fh Function 1600h) determines whether Windows is running. If a program intends to use a Windows function, it must first use this function to make sure that Windows is running.

This function has no parameters.

• The return value is 00h or 80h in the AL register if Windows is not running. If Windows is running, the return value is the major version number in the AL register, and the minor version number in the AH register.