Windows 3.1 Device Drivers (ddag31qh.hlp) (Table of Contents; Topic list)
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The pages on this site contain documentation for very old MS-DOS software, purely for historical purposes. If you're looking for up-to-date documentation, particularly for programming, you should not rely on the information found here, as it will be woefully out of date.
Interrupt 2Fh Function 1609h
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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.
 
Return Value
 
This function has no return value.
 
Comments
 
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.
 
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