INT 66 - PenDOS - PMOUSE - ALTERNATE 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. AH = function (58h-5Fh) Note: these functions exactly duplicate AH=50h-57h