Enhanced Small Disk Interface (ESDI) was a disc 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 generalising 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.
ESDI enjoyed popularity in the mid-to-late 1980s, when SCSI and ATA were young and immature, and ST-506 just wasn't fast or flexible enough. ESDI could handle data rates of 10, 15, or 20 megabits per second (as opposed to ST-506's top speed of 7.5 megabits), and many high-end SCSI drives of the era were actually high-end ESDI drives with SCSI bridges 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.
References
This article was originally based on material from the Free On-line Dictionary of Computing, which is licensed under the GFDL.
The disk surface and the drive's internal environment must therefore be kept immaculate to prevent damage from fingerprints, hair, dust, smoke particles, etc., given the submicroscopic gap between the heads and disk.
EnhancedSmallDiskInterface (ESDI) also supported multiple data rates (ESDI drives always used 2,7 RLL, but at 10, 15 or 20 megabits per second), but this was usually negotiated automatically by the drive and controller; most of the time, however, 15 or 20 megabit ESDI drives weren't downward compatible (i.e.
For many years, hard disks were large, cumbersome devices, more suited to use in the protected environment of a data center or large office than in a harsh industrial environment (due to their delicacy), or small office or home (due to their size and power consumption).
Information is written to the disk by transmitting an electromagnetic flux through an antenna or read-write head that is very close to a magnetic material, which in turn changes its polarization due to the flux.
The disk surface and the drive's internal environment must therefore be kept immaculately clean to prevent damage from fingerprints, hair, dust, smoke particles, etc. given the submicroscopic gap between the heads and disk.
ESDI (EnhancedSmallDiskInterface) was an interface developed by Maxtor to allow faster communication between the PC and the disk.
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