Abstract: An improved method and circuitry for amplifying and processing detected pairs of input signals, in a manner that provides excellent DC accuracy, wideband signal handling capability and fast overload recovery, are disclosed. The invention is particularly suitable for use as a preamplifier for pairs of sensed photodetector current signals. Common base and emitter coupled circuits are arranged in various configurations to simultaneously process pairs of detected signals to provide normalized analog differential output current signals that can be directly used by amplifier circuits without concern for overloading of the amplifier as a result of severe overload signals detected by the input sensors. The circuitry readily accommodates external real-time gain control.

Abstract: An improved method of configuring digital information in a recording storage media so as to significantly increase the information storage capacity of the media, and the media containing such configured digital information are disclosed. Information containing markers are arranged and configured along tracks in the media in a manner such that markers of adjacent tracks are offset relative to one another. Inter-track spacings of arcuately shaped tracks on a storage media are progressively reduced as a function of the radial spacing of the tracks from their center of curvature, further increasing the marker packing density. Return to zero pulsed modulation schemes are employed to maximize the amount of information recorded in a given number of marker locations. Drive means for reading digital information configured on storage media according to the principles of this invention are provided.

Abstract: A method and apparatus for positioning and tracking a Random Access Memory (RAM) optical head over an information storage media having a plurality of tracks formed by optically readable deformations ("pits") in the media including, a central controller, a laser diode optical-system carrying head which is movable transversely of the tracks in incremental steps for coarse positioning of the head over a selected band of tracks and a servomechanism which positions the laser's objective lens over a specifically addressed track and maintains it there until another track is addressed. Also discussed is a unique method of generating a tracking error signal as an input to the servomechanism which includes the asynchronous detection of a sector mark and the generation of an independent clocking signal from the synchronous detection of off-track pairs of pits spaced uniformly between other data in the track to produce the tracking error signal.