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)