1. A disk array controller which operatively connects a host computer to an array of disk drives, the host computer including a system memory, the disk array controller comprising: a plurality of disk drive controllers, each disk drive controller connected to and configured to control at least one disk drive of the array; a microcontroller which dispatches controller commands to the disk drive controllers over a control bus to initiate transfers of input/output (I/O) data between the disk drives and the host computer, at least some of the controller commands including system memory addresses for performing said transfers, the microcontroller responsive to I/O requests generated by the host computer; and an automated processor which transfers I/O data between at least the disk drive controllers and the system memory, the automated processor connected to the plurality of disk drive controllers by a packet bus which is separate from the control bus, and connected as a bus master to a bus of the host computer, the automated processor responsive to transfer commands and target addresses received from the disk drive controllers over the packet bus, at least some of the transfer commands specifying transfers of I/O data between the disk drive controllers and the system memory.