An embodiment of the invention comprises a retractor for use with a depth finder unit. The supersonic propulsion system includes a plurality of systems for efficiently creating cyclic detonations and at least one rocket booster device. The coarse tuning circuit includes divide value generation circuitry that provides an integer divide value to an N divider of the PLL during coarse tuning and a fractional-N sequence to the N divider during fractional-N operation. A bus operation is initiated based on the memory barrier command. Investigative tools allow flexible queries of the conversation database.