Enhanced Small Disk Interface

Enhanced Small Disk Interface (ESDI) was a disk interface designed by Maxtor Corporation in the early 1980s to be a follow-on to the ST-506 interface. ESDI improved on ST-506 by moving certain parts that were traditionally kept on the controller (such as the data separator) into the drives themselves, and also generalizing the control bus such that more kinds of devices (such as removable disks and tape drives) could be connected. ESDI used the same cabling as ST-506 (one 34-pin common control cable, and a 20-pin data channel cable for each device), and thus could easily be retrofitted to ST-506 applications.