SCSI 是 Small Computer System Interface 的縮寫，外置式 25 針接口為掃描儀等低速設備使用，接口外觀為母插座：
連接電纜插頭為 25 針公插頭：
|
引腳定義 |
|
Pin |
Name |
Dir |
Description |
|---|---|---|---|
|
1 |
GND |
Ground | |
|
2 |
DB1 |
Data Bus 1 | |
|
3 |
DB3 |
Data Bus 3 | |
|
4 |
DB5 |
Data Bus 5 | |
|
5 |
DB7 |
Data Bus 7 | |
|
6 |
GND |
Ground | |
|
7 |
/SEL |
Select | |
|
8 |
GND |
Ground | |
|
9 |
TMPWR |
Termination Power | |
|
10 |
/RST |
Reset | |
|
11 |
C/D |
Control/Data | |
|
12 |
I/O |
Input/Output | |
|
13 |
GND |
Ground | |
|
14 |
DB0 |
Data Bus 0 | |
|
15 |
DB2 |
Data Bus 2 | |
|
16 |
DB4 |
Data Bus 4 | |
|
17 |
DB6 |
Data Bus 6 | |
|
18 |
PARITY |
Data Parity | |
|
19 |
GND |
Ground | |
|
20 |
/ATN |
Attention | |
|
21 |
/MSG |
Message | |
|
22 |
/ACK |
Acknowledge | |
|
23 |
BSY |
Busy | |
|
24 |
/REQ |
Request | |
|
25 |
GND |
Ground |