Disk drive and method for data transfer initiated by optional disk-drive commands on a serial interface that only supports standard disk-drive commands

In a disk drive connected to a host computer, and responsive to first-type disk-drive commands associated with specific disk-drive operations and to second-type disk-drive commands associated with optional disk drive operations, the disk drive including a disk, a head actuated radially over the disk, a disk control system for responding to disk-drive commands and for accessing data storage locations on the disk through the head, and a serial interface for coupling the disk control system to the host computer when the disk drive is connected to the host computer, wherein the serial interface is configured to transfer first-type disk-drive commands from the host computer to the disk control system and is not configured to transfer second-type disk-drive commands from the host computer to the disk control system, a method for transferring disk-drive data between the disk drive and the host computer, comprising:

• embedding a second-type disk-drive command for data transfer within a first data block accessible using an initial first-type disk-drive command, the first type disk-drive command identifying the disk-drive data for transfer;
• transmitting the initial first-type disk-drive command from the host computer through the serial interface to the disk control system, wherein the initial first-type disk-drive command causes the first data block to be transferred from the host computer to the disk control system;
• extracting the embedded second-type disk-drive command from the transferred first data block;
• providing the extracted second-type disk-drive command to the disk control system;
• transmitting a status response, based on the extracted second-type disk-drive command, from the disk drive to the host computer;
• transmitting at least one additional first-type disk-drive command, responsive to the status response, from the host computer through the serial interface to the disk control system for transferring the identified disk-drive data between the host computer and the disk drive.