US Patent 7487268 Long latency interface protocol

A system includes a read/write channel and a hard disk controller. The hard disk controller includes a latency-independent interface that communicates with the read/write channel. A serial control data circuit transmits a serial control data signal including serial control data, wherein the serial control data signal has a variable number m of words, wherein each of said m words comprises n bits, and wherein at least one of said n bits of each of said m words includes information indicating whether a subsequent word of said serial control data signal will follow. A data circuit that transmits or receives data under the control of the serial control data signal.