Disk storage subsystem with internal parallel data path and non-volatile memory

A disk storage subsystem for storing data supplied by mass storage interface circuitry and retrieving data needed by said interface circuitry, wherein said interface circuitry specifies a storage location by address information, said disk storage subsystem comprising:

• a volatile storage medium;
• a parallel path;
• a nonvolatile media;
• a control circuit comprising a first port, a second port, a first line carrying signals and a second line carrying signals, wherein said first port is operatively coupled to said nonvolatile media, said second port is operatively coupled to said parallel path, said first line is operatively coupled to said volatile storage medium thereby to carry control signals between said control-circuit and said volatile storage medium and said second line is operatively couplable to said interface circuitry;
• wherein said parallel path is also operatively coupled to said volatile storage medium;
• wherein in a first mode of operation, in response to a first signal on said second line from said interface circuitry, said control circuit stores data over said parallel path received from said interface circuitry at a location in said volatile storage medium corresponding to said address information;
• in a second mode of operation, in response to a second signal on said second line from said interface circuitry, said control circuit retrieves data over said parallel path from a location in said volatile storage medium corresponding to said address information and provides said retrieved data to said interface circuitry;
• and
• further wherein said control circuit can store parallel data received on said parallel path into said nonvolatile media and supply parallel data from said nonvolatile media on said parallel path, wherein said disk storage subsystem is addressable by said interface circuitry in a format readable by a disk drive.