High packing density disk cartridge with write protect mechanism

Abstract From the Canadian patent

A disk cartridge includes a first identification recess for serving to prevent data stored on a magnetic disk from being erroneously erased from the disk and to prevent new data from being erroneously written on the disk, a second identification recess for discriminating a 4 or 6 MB disk cartridge from a 1 or 2 MB disk cartridge, and a third identification recess for discriminating a high packing density disk cartridge from other type disk cartridge. The third identification recess is arranged at a point located on a straight line drawn between two recesses which are formed on the opposed side edges of the disk cartridgeat a location neighboring the front edge thereof.