Editing Enhanced Small Disk Interface (section)

{{Short description|Disk interface}}
'''Enhanced Small Disk Interface''' ('''ESDI''') is a [[hard disk drive interface]] designed by [[Maxtor Corporation]] in 1983 to be a follow-on to the [[ST-506|ST-412/506]] interface.<ref name="glass198902">{{Cite magazine |last=Glass |first=Brett |date=February 1989 |title=Hard Disk Interfaces |url=https://archive.org/details/eu_BYTE-1989-02_OCR/page/n350/mode/1up?view=theater |access-date=2024-10-08 |magazine=BYTE |pages=293-297}}</ref> 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]]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 [[Advanced Technology Attachment|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&nbsp;Mbit/s (as opposed to ST-506's top speed of 7.5&nbsp;Mbit/s), and many high-end SCSI drives of the era were actually high-end ESDI drives with SCSI [[Protocol_converter|bridge]]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.