ESDI 是 Enhanced Small Device Interface 的縮寫，早在 1980 年由 Maxtor 公司開發，是老式硬盤的接口，它的電纜由兩部分組成，ESDI 接口在接口卡側的外觀為 34 腳和 20 腳公插針：
在硬盤側為 34 腳的控制信號和 20 腳數據信號：
|
引腳定義 |
34 腳的控制信號：
|
Pin |
Name |
Description |
|---|---|---|
|
2 |
|
Head Sel 3 |
|
4 |
|
Head Sel 2 |
|
6 |
|
Write Gate |
|
8 |
|
Config/Stat Data |
|
10 |
|
|
|
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 |
20 腳的數據信號：
|
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 |