mov ax, 1609h ; Windows Begin Exit
int 2fh ; multiplex interrupt
Windows Begin Exit (Interrupt 2Fh Function 1609h) notifies MS-DOS device drivers and TSRs that Windows is about to terminate. Windows calls this function when it first begins termination to allow a device driver or TSR to prepare for a return to a non-Windows environment.
This function has no parameters.
This function has no return value.
Windows calls this function at the start of the Sys_VM_Terminate device control call. All virtual devices still exist, so a device driver or TSR can call a virtual device's entry point if necessary.
Windows does not call this function in the event of a fatal system crash.
Windows may execute real-mode code after this function has been called and before 386 enhanced-mode Windows returns to real mode. It is the responsibility of the device driver or TSR to detect and properly handle these situations.