# ESDI

ESDI=Enhanced Small Device Interface.
Developed by Maxtor in the early 1980's as an upgrade and improvement to the ST506 design.

(at the controller)
(at the controller)

(at the harddisk)
(at the harddisk)

34 PIN IDC MALE at the Controller.
20 PIN IDC MALE at the Controller.

34 PIN IDC FEMALE at the Harddisk.
20 PIN IDC FEMALE at the Harddisk.

## Control connector

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

Contributor: Joakim Ögren

Source:
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Copyright © The Hardware Book Team 1996-2001.
May be copied and redistributed, partially or in whole, as appropriate.
Document last modified: 2001-06-07