Abstract: A spindle motor control circuit 20 for controlling the acceleration and position locking of a spindle motor 22 includes a first mode of operation whereby the spindle motor 22 is commutated through use of an external clock 32, 34. The control circuit 20 then causes the spindle motor 22 to be self-commutation based on the clock developed from transitions detected by a transition detector 71, which transitions are signals provided from the phase windings of the spindle motor 22. A final mode includes the reading of servo information from the servo sectors on the disc in order to control the final acceleration and position of the spindle motor 22.

Abstract: Two power switching transistors have their emitter and collector connected together respectively. A high level DC voltage is connected across the transistors. The junction of the two transistors is connected by way of a load sensing resistor to a power bus and to the primary of an auxilary transformer. A secondary of the auxiliary transformer is coupled to the input of a transcondance limiting amplifier whose output is coupled to a drive amplifier. The output of the drive amplifier is coupled to the primary of a timing transformer. Two secondaries of the timing transformer are coupled to the two transistors respective for providing drive for the transistors. The auxiliary transformer, transconductance amplifier, drive amplifier, and timing transformer are coupled together in a positive feedback loop forming a high frequency oscillator with the two transistors for converting the DC voltage to a high frequency voltage.

Abstract: A magnetic disc has a plurality of video track segments for storing distinct fields of video information. A look-up track is provided on the disc and segmented to store indirect address data which may be represented by random numbers, and which are related to the video information fields. Both the look-up track segments and the video track segments are numbered sequentially. Each video track segment is permanently associated with a look-up track segment.A movable transducer is associated with both the video tracks and the look-up track. A counter circuit is provided to indicate periodically the instant look-up segment numbers with respect to the instant position of the rotating cyclical storage device and in synchronism therewith. A first comparator circuit compares an indirect address input request with the indirect addresses recorded on the look-up track.