Patent ID: 7787206

Claim:
A disk drive system comprising: a read channel for a disk drive to read data from and write data to a disk, in which the read channel includes a processing engine to process commands from a disk controller; an interface coupled between the read channel and the disk controller, in which a plurality of differential pair signal lines are resident thereon to communicate both data and command signals between the read channel and the disk controller; a preamplifier coupled to the read channel and separate from the read channel, in which the preamplifier includes at least one preamp register to configure operation of the preamplifier, the at least one preamp register being controlled by a preamp register access command communicated via a non-differential command line disposed between the preamplifier and the read channel processing engine; and wherein the read channel processing engine is operable to receive a command from the disk controller over the differential pair signal lines, process the command from the disk controller to determine if the command is for the read channel or for the preamplifier, and to access the at least one preamp register via the non-differential command line as the preamp register access command, when the command is for the at least one preamp register.