INT 15 - SYSTEM - WAIT ON EXTERNAL EVENT (CONVERTIBLE and some others) AH = 41h AL = condition type (see #00463) BH = condition compare or mask value BL = timeout value times 55 milliseconds 00h means no timeout DX = I/O port address if AL bit 4 set ES:DI -> user byte if AL bit 4 clear Return: after event or timeout occurs Note: call AH=C0h and examine bit 3 of feature byte 1 to determine whether this function is supported SeeAlso: AH=83h,AH=86h,AH=C0h