Implementation of the Enhanced Small Device Interface Host Adapter/ Controller for Five and One Quarter Inch Disk Drives
Original Publication Date: 1987-Sep-01
Included in the Prior Art Database: 2005-Feb-01
This article describes a method which allows the attachment of the highest capacity 5-1/4-inch fixed disk drives to low and midrange computing systems. A host Enhanced Small Device Interface (ESDI) adapter is implemented with a generic interface disk data controller chip combined with discrete hardware and microprocessor-controlled parts. The ESDI provides control for low-end direct access storage devices (DASDs) and tape drives. The protocol evolved from the accepted ST-506 interface standard for 5-1/4-inch hard drives; yet it provides a step increase in relative performance and functionality. The ESDI maintains essentially the same physical interface structure as ST-506, but adds a new logical protocol layer to facilitate intelligent drives.