An improved, Philips-type tape cassette having a shiftable tab for selectively blocking the opening formed by the removal of the conventional knock-out tab used to provide a means for determining the presence of pre-recorded material on the tape carried by the cassette. The two shells of the cassette have improved tongue and groove structure at the adjacent sides and ends to fit the shells together and to prevent relative movement therebetween. Relatively wide front and rear end walls on one of the shells provide a pair of beams of increased thickness to prevent bending of the cassette so as to maintain its structural integrity. An improved internal lock is provided near the central part of the rear wall where an attachment screw would be impractical. Each hub of the cassette has an improved leader-holding insert which is received within an outer peripheral recess and supports the tape across the recess to avoid "spoking" in the tape pack formed on the hub. Each of a pair of improved idler posts integral with one of the shells provides a pair of spaced, cylindrical bearing surfaces while providing a space for receiving lubricant. Tape guides near the open, tape-exposing extremity of the cassette are perpendicular to the inner surface of each shell to minimize the "barber pole" effect on the tape.

An apparatus for automatically reproducing recorded signals from a rotary recording medium, in accordance with the mode in which signals were recorded. The reproducing apparatus comprises a micro-computer which produces a two-bit mode control signal and a one-bit muting signal. The one-bit muting signal puts one of two processing circuits in a non-operational state, so that the other of the two processing circuits can perform the signal processing in accordance with the mode specified by the two-bit mode control signal. Four codes constituted by the two-bit mode control signal are commonly used to specify four reproducing modes of a video rotary recording medium and four reproducing modes of an audio rotary recording medium.

A clock utilized in conjunction with a broadcast receiver is coordinated with a control so that a pre-recorded audible time chime signal is automatically played directly through the loudspeaker of the receiver. The clock and control cause the chime signal to be played through the speaker, whether the receiver switch is in on or off position. When the receiver is on and broadcast material is being directed through the speaker, the control substitutes the chime signal for the broadcast material. The control system is connected between the clock and the audio stage of the receiver and is adapted to by-pass the receiver's on-off switch to provide power to the receiver in the event the switch is in off position. The control is actuated by a switch which is responsive to the position of a clock shaft and, in the embodiment shown, includes a pair of tape reels which are driven in forward and reverse direction in response to control signals on the tape. The tape is four track and includes a pair of control signal channels and a pair of audio chime channels, one of each channel being provided for each direction of tape movement. The tape direction is reversed at either end in response to control signals, to thereby provide a continuously operating automatic system. The chime changes with the change in time to provide the correct time of day.

A disk drive includes a cast base upon which is mounted the disk stack-spindle assembly and the actuator assembly and a cover that is loosely received by the cast base to form the head-disk enclosure. The cover is secured and sealed to the cast base by a malleable metal foil tape that surrounds the enclosure and continuously overlies the interface between cover and base. The tape complies with the surface irregularities and does not creep, to provide permanent shielding and sealing between base and cover. Further, cables exiting the enclosure may be sealed using a piece of double sided adhesive which is interposed between cable and casting followed by application of the malleable foil tape thereover. Thus in a compact device, no significant thickness is added to the enclosure wherein a maximum available height is used to house the stack of disks while providing noise and EMC shielding in addition to securing and sealing the cover.