Abstract: A selectively openable closure mechanism for a magnetic recording disc cartridge for cooperating with a probe member connected to a disc drive unit provides for selectively opening access through an aperture in the cartridge to the interior thereof when the cartridge is inserted into the drive unit and the closure-actuating probe member is received into the cartridge and for closing access to the aperture when a cartridge is removed from the drive unit and the probe member is withdrawn from the cartridge, the mechanism including an arcuate guide track formed in at least one of the top or bottom panels of the cartridge, at least one arcuate door slidably carried by the guide track for selective movement between a closed position and an open position and structure connected to the door for engaging and capturing the probe member upon its reception into the cartridge and for driving the door from the closed position to the open position and back to the closed position upon insertion and withdrawal of the probe w

Abstract: Apparatus is disclosed for centering and mounting a magnetic recording disc on a disc drive and includes on the recording disc a deflectable member radially inward of the recording surfaces, to which member is attached a generally spherically curved centering member which is received into a hollow portion of the disc drive spindle, and positioned radially between the disc recording surface and the deflectable portion of the deflectable member is a rigid hub portion for reception and driving engagement with the disc drive spindle.