Abstract: A program controlled digital computer is operated according to a utility program, such as a sort program which manages input/output directly (using very efficient execute channel programs (EXCP) or basic sequential access method (BSAM) facilities of the operating system), but in such a way as to provide to the caller (that is, the application program) the status and error information that is required. This is accomplished by defining an interface between the caller and sort enabling the caller to specify the names of the input and output data sets, the locations of routines to be executed for input and output, the locations of routines to be executed upon exit from input/output routines, and data areas for status information.

Abstract: A cartridge comprises a housing containing a flexible record disk connected to a hub that is rotatable relative to the housing by a drive spindle. The cartridge is configured so as to be reversibly mountable on the spindle, for enabling the transducer to access and transducingly engage selectively either face of the disk through respective slots in the housing. The housing is formed of two substantially identical portions, each providing a Bernoulli surface having parts extending at equal angles in opposing divergent directions from a central part that is perpendicular to the plane of disk rotation. In an alternate configuration, the Bernoulli surface has only one part extending in a divergent direction from a remaining part that is perpendicular to the plane of disk rotation.