Abstract: An environmental indicator assembly in a floppy disk cassette provides a warning signal when the cassette has been subjected to either a high-moisture or a high-temperature condition either environment being potentially harmful to the disk. The indicator assembly includes a wax which melts in a high-temperature environment and a hygroscopic salt which breaks down in a high-moisture condition. If either the wax or the salt changes from a solid form, a warning flag automatically moves into a position viewable to a cassette user.

Abstract: A cartridge comprises a rigid peripheral wall sandwiched between a pair of similarly rigid major surfaces, to form a compartment containing a disk arranged for rotation about a central axis. The cartridge obviates the need to have relative axial movement between the disk and a record/playback transducer head as the cartridge is loaded into a drive mechanism. To that end, a brake mechanism latches the disk axially, as well as radially, in its operative plane as the cartridge is loaded; additionally, the cartridge exposes the disk sufficiently to provide interference-free access to it by the transducer head. For that purpose, at least one of the major surfaces has a head-access opening extending to the peripheral wall, which, in turn, defines a relatively narrow bridge-like member, comparable in width to the operative plane of the disk, extending laterally, in the disk plane, from one side to the other side of the head-access opening.

Abstract: A write protect mechanism is disclosed for a cartridge of the type having top and bottom plates and an information recording medium interposed therebetween. The write protect mechanism comprises a button visible through an aperture in one of the plates and slideably moveable in the aperture between a write protect position and a write enabled position. In the write protect position, an interfacing recording device is actuated to prevent recording so that information previously recorded on the disk will not be inadvertently erased. In the write enabled position, the recording device is actuated to record information on the disk. The button further has a flag adapted to extend into a gap in a rear peripheral wall joining the top and bottom plates to visibly indicate that the button is in the write protect position and that information can not be recorded on the medium. When the flag is retracted, this visibly indicates that recording, if not prevented, could inadvertently erase previously recorded information.

Abstract: A flexible magnetic recording media, such as disks or magnetic tape, having a non-magnetic layer intermediate the substrate and magnetic recording layers providing improved durability of the magnetic recording layer including a binder comprised of non-magnetic particles of .alpha.Fe.sub.2 O.sub.3 with similar physical properties as those of the magnetic recording layer (.gamma.Fe.sub.2 O.sub.3 or Co-.gamma.Fe.sub.2 O.sub.3) and a reservoir of lubricant.