INT 15 - TopViewTopView, DESQview, TaskView, OmniView, other compatibles - "GETBIT" - DEFINE A 2ND-LEVEL INTERRUPT HANDLER
	AX = 1013h
	ES:DI -> FAR service routine
Return: BX = bit mask indicating which bit was allocated
	    0000h if no more bits available
SeeAlso: AX=1014h,AX=1015h
Note:	only a few TopViewTopView, DESQview, TaskView, OmniView, other compatibles/DESQview API(Application Program[ming] Interface) The defined set of calls which a program may make to interact with or request services of the operating system or environment under which it is running.  Because the inputs and outputs of the calls are well-defined, a program using the API can continue using the identical calls even if the internal organization of the program providing the API changes. calls are allowed during a hardware
	  interrupt; if other calls need to be made, the interrupt handler
	  must schedule a 2nd-level interrupt with "SETBIT" (AX=1015h)