High-performance adaptive-speed/CAV CD-ROM drive

This paper describes a novel type of CD-ROM drive which can automatically distinguish between two basic operating modes: continuous playback and continuous access. The drive, based on the adaptive-speed technology, is optimized for a very high data throughput during sustained read-out using a new cubic overspeed profile. In addition, by detecting the state of continuous access and switching the spindle motor into a CAV (constant angular velocity) loop, the drive features very low power consumption. Two dedicated firmware algorithms which can detect one of the two operating modes either at the bit-engine level or at the data-path level are also presented. While implementing the algorithm at the data-path level, the paper also includes a novel technique for the optimization of the data flow via controlling the speed of the spindle motor. A better buffer management can therefore be achieved. Last but not least, the cubic overspeed profile is shown to be optimal not only for sustained playback but also while the drive is performing either a unique seek action or a short sequence of seeks.