Hardware (Logic) Control of Headswitch for a Hard Magnetic Disk File With Enhanced Small Device INTERFACE
Original Publication Date: 1989-Jan-01
Included in the Prior Art Database: 2005-Jan-26
This hardware state machine gives faster response to the Enhanced Small Device Interface (ESDI) controller when a head switch occurs, and it changes heads on the file at a precisely controlled point. (Image Omitted) The hardware (logic) controls head switches for a hard file using sector servo imbedded on the data surfaces with the ESDI. Since the host performs head switches when using the ESDI, a file with sector servo must control the head switch time so that servo read is not disturbed. In addition, the servo microprocessor is notified of head switches to perform a "settle" when it occurs. Command Complete is controlled by the logic to allow head switches during seeks and other ESDI operations. The Head Select logic has the following objectives: 1.