Control Signal Connector J1 is a 34-pin board edge connector on the Device Electronics board. The signals on this connector control the drive and transfer drive status to the host controller.
Data Transfer Connector J2 is a 20-pin board-edge connector on the Device Electronics board. The signals on this connector contain read or write data.
DC Power Connector J3 is a 4-pin keyed connector. It is used to supply +5V and +12V to the drive.
Ground Connector J4 is a 3/16-inch spade lug located on the HDA, and is used for grounding purposes.