INT 15 C - OS HOOK - DEVICE CLOSE                                               
	AH = 81h
	BX = device ID
	CX = process ID
	CF clear
Return: CF clear if successful
	    AH = 00h
	CF set on error
	    AH = status (see #00496)
Note:	this function should be hooked by a multitasker which wishes to keep
	  track of device ownership; the default BIOS(Basic Input/Output System) A set of standardized calls giving low-level access to the hardware.  The BIOS is the lowest software layer above the actual hardware and serves to insulate programs (and operating systems) which use it from the details of accessing the hardware directly. handler merely returns
	  successfully
SeeAlso: AH=80h,AH=82h