INT 15,41 - Wait on External Event (convertible only)

	AH = 41h
	AL = condition type:

		|7|6|5|4|3|2|1|0|  AL
		 | | | | | `-------- conditions (codes) to wait for
		 | | | | `--------- reserved
		 | | | `---------- 1=port address/0=user byte
		 `--------------- reserved

	Condition codes:

	     0 = any external event
	     1 = compare and return if equal
	     2 = compare and return if not equal
	     3 = test and return if not zero
	     4 = test and return if zero

	BH = condition compare or mask value
	BL = time-out value times 55 ms, 0 if no time limit
	DX = I/O port address (if AL bit 4 = 1)
	ES:DI = pointer to user byte (if AL bit 4 = 0)