Storage System Interface Protocol Optimized for Low Cost
Original Publication Date: 1988-Mar-01
Included in the Prior Art Database: 2005-Feb-14
A storage system interface is described having a reduced set of connecting cables between a device and the host system. Data and control information are communicated between the host and the device in a duplex link. Signals on the link are transmitted serially with the signals encoded under a coding scheme (e.g., Modified Frequency Modulation, Run Length Limited (RLL) (2,7) code or (1,7) code) where a stable clock signal can be derived from the received data using a variable frequency oscillator. Frequency of transmission is reduced by further encoding the signals using a coding scheme, such as the Non-Return-to-Zero Mark (NRZM). Thus, information across the interface is encoded using a combination of the RLL and the NRZM codes. Device commands and status are sent on the interface between data bursts.