A compatible data transfer apparatus for use with first and second tape assemblies such as multitrack digital magnetic tape cassettes on which data are recorded with different formats or with different densities. Typically, in order to discriminate between the two types of tape assemblies, a beginning-of-tape (BOT) sensor is utilized which optically detects a BOT hole usually formed in this kind of tape cassette. The two types of tape assemblies have their BOT holes formed at different distances from optically detectable starting position of the tape such as the boundary between the transport leader tape section and the opaque data storage section. The BOT sensor may be connected to a programmed microcomputer or to a devoted identification circuit whereby the loaded tape assembly is identified as the first or second type depending upon the distance of the BOT hole from the starting tape position. A tape select switch is automatically actuated for connecting the transducer to a reproduction circuit to either of two reproduction circuits provided for the two types of tape assemblies.