CALL xxxxh:xxxxh - CTMMSYS.SYS - 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. Program: CTMMSYS.SYS is the Creative DOS Multimedia Architecture Integration driver InstallCheck: see INT 21/AX=4402h"CTMMSYS" SeeAlso: INT 21/AX=4402h"CTMMSYS"