Abstract: A bidirectional, multitrack magnetic tape subsystem is disclosed which is for use with a two-reel, belt-driven tape cartridge in which the tape tension increases linearly with tape travel in either direction. Upon completion of writing or reading data along one track, the tape is stopped at one extremity thereof and then reversed toward the other extremity, with the head unit held on said one track. Only after the tape has been reversed a predetermined short distance is the head unit shifted from said one to another track, preferably with the tape held at a standstill during such shifting. Thus the head unit travels between the bidirectional tracks on the tape when the tape tension is substantially at a minimum, thereby avoiding possible damage to the tape.

Abstract: A read/write head unit is moved across a reference burst track on magnetic tape from one longitudinal edge thereof toward the other through a series of transverse locations. The peak amplitude of the output from a read amplifier, representative of the reference burst, is detected at each transverse location. The set of amplitude values thus obtained is then referred to data, compiled by testing a number of tape transports and a number of tape assemblies, representative of standard categories each comprising an allowable range of deviations from a different standard set of amplitude values and a corresponding distance to be traversed by the head unit from the last of the series of transverse locations to the centerline of the reference burst track.