Enhanced Small Disk Interface (ESDI) is an obsolete disk interface designed by
Maxtor Corporation
Maxtor was an American computer hard disk drive manufacturer. Founded in 1982, it was the third largest hard disk drive manufacturer in the world before being purchased by Seagate in 2006.
History
Overview
In 1981, three former IBM employ ...
in the early 1980s to be a follow-on to the
ST-412/506 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 drive
A tape drive is a data storage device that reads and writes data on a magnetic tape. Magnetic tape data storage is typically used for offline, archival data storage. Tape media generally has a favorable unit cost and a long archival stability.
...
s) could be connected. ESDI uses 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.
ESDI was popular in the mid-to-late 1980s, when
SCSI and
IDE technologies were young and immature, and ST-506 was neither fast nor flexible enough. ESDI could handle data rates of 10, 15, or 20 Mbit/s (as opposed to ST-506's top speed of 7.5 Mbit/s), and many high-end SCSI drives of the era were actually high-end ESDI drives with SCSI
bridge
A bridge is a structure built to span a physical obstacle (such as a body of water, valley, road, or rail) without blocking the way underneath. It is constructed for the purpose of providing passage over the obstacle, which is usually somethi ...
s integrated on the drive.
By 1990, SCSI had matured enough to handle high data rates and multiple types of drives, and ATA was quickly overtaking ST-506 in the desktop market. These two events made ESDI less and less important over time, and by the mid-1990s, ESDI was no longer in common use.
Connector pinouts
References
Micropolis ESDI X3.170-90 Interface SpecificationESDI Specification, Magnetic Peripherals Inc, 1984IBM ESDI Fixed Disk Drive Adapter/A Technical Reference
{{Computer-bus
Computer storage buses