It appears that you are using AdBlocking software. The cost of running this website is covered by advertisements. If you like it please feel free to a small amount of money to secure the future of this website.

ESDI = Enhanced Small Device Interface

Developed by Maxtor in the early 1980’s as an upgrade and improvement to the ST506 design.

Though ESDI and ST506/412 drives share similar looking cables, even to the point of having a twist, the actual data and control signals are very different. One should never mix components from these two drive types. While the ST506/412 interface utilises a standard pulse code to transmit data between the drive and controller, ESDI uses a pulse code that does not require the level to return to zero between pulses. This format is refereed to as NRZ, or Non Return to Zero. By utilising NRZ, the clock that data is transferred by can be increased, there by increasing the throughput to and from the ESDI disk.

Image:conn_idc34m.gif 34 PIN IDC MALE at the Controller

Image:conn_idc20m.gif 20 PIN IDC MALE at the Controller

Image:conn_idc34f.gif 34 PIN IDC FEMALE at the Harddisk

Image:conn_idc20f.gif 20 PIN IDC FEMALE at the Harddisk

Control connector

Pin Name
2 Head Sel 3
4 Head Sel 2
6 Write Gate
8 Config/Stat Data
10 Transfer Acknowledge
12 Attention
14 Head Sel 0
16 Sect/Add MK Found
18 Head Sel 1
20 Index
22 Ready
24 Transfer Request
26 Drive Sel 1
28 Drive Sel 2
30 Drive Sel 3
32 Read Gate
34 Command Data

Note: All odd are GND, Ground.

Data connector

Pin Name
1 Drive Selected
2 Sect/Add MK Found
3 Seek Complete
4 Address Mark Enable
5 (reserved, for step mode)
7 Write Clock+
8 Write Clock-
9 Cartridge Changed
10 Read Ref Clock+
11 Read Ref Clock-
12 GND
13 NRZ Write Data+
14 NRZ Write Data-
15 GND
16 GND
17 NRZ Read Data+
18 NRZ Read Data-
19 GND
20 GND


Category:Data Storage Connectors


© 1998-2019 – Nicola Asuni - - All rights reserved.
about - disclaimer - privacy