| Pin | Signal | Pin | Signal |
|---|---|---|---|
| 1 | Ground | 2 | -HD SLCT 3 |
| 3 | Ground | 4 | -HD SLCT 2 |
| 5 | Ground | 6 | -Write Gate |
| 7 | Ground | 8 | -Seek Cmplt |
| 9 | Ground | 10 | -Track 0 |
| 11 | Ground | 12 | -Write Fault |
| 13 | Ground | 14 | -HD SLCT 0 |
| 15 | KEY (no pin) | 16 | not connected |
| 17 | Ground | 18 | -HD SLCT 1 |
| 19 | Ground | 20 | -Index |
| 21 | Ground | 22 | -Ready |
| 23 | Ground | 24 | -Step |
| 25 | Ground | 26 | -DRV SLCT 0 |
| 27 | Ground | 28 | -DRV SLCT 1 |
| 29 | Ground | 30 | not connected |
| 31 | Ground | 32 | not connected |
| 33 | Ground | 34 | -Direction IN |
ST-506/412 HDD-Interface - 20-Pin Data Connector
Pin
Signal
Pin
Signal
1
-DRV SLCTD
2
Ground
3
not connected
4
Ground
5
not connected
6
Ground
7
not connected
8
Key (no pin)
9
not connected
10
not connected
11
Ground
12
Ground
13
+MFM Write
14
-MFM Write
15
Ground
16
Ground
17
+MFM Read
18
-MFM Read
19
Ground
20
Ground
Please see the LEGAL - Trademark notice.
Feel free - send a 
for any BUG on this page found - Thank you.