INT 16 CU - Microsoft QBASIC internal - MICROSOFT COOPERATION WITH TSR(Terminate and Stay Resident) A program which remains in memory after terminating in order to provide services to other programs or the user.  The name comes from the name of the DOS function call used to remain in memory after termination.
	AX = 55FEh
	DX = function
	    0000h initialize
		ES:BX -> ??? function
		ES:CX -> ??? structure
	    FFFFh shutdown/reset
Return: AX = result
	    4D4Bh only the INT 1B handler will be installed.
	    other: handlers for INT 08, INT 09, INT 16, INT 1B, and INT 1C
		  are installed
Notes:	The pointer in ES:CX seems to point at a structure defining a callback
	  function when new keyboard keys are pressed. If a TSR(Terminate and Stay Resident) A program which remains in memory after terminating in order to provide services to other programs or the user.  The name comes from the name of the DOS function call used to remain in memory after termination. returns
	  AX=4D4Bh, QBASIC will stop (with IRQ(Interrupt ReQuest) A hardware line connected to the interrupt controller chip which signals that a CPU interrupt should be generated.'s and interrupts enabled).
	these calls are also made by MS-DOS 6.0's DOSSHELL at startup, exit,
	  and before/after shelling out
	since EDIT.COM and HELP.COM merely invoke QBASIC, those two programs
	  will also cause this interface to be invoked
	K3PLUS v6.07+ supports this function, but will never invoke the
	  callback function
SeeAlso: AX=5500h,AX=AF4Dh,INT 1A/AX=3601h