All X68000s (even the SASI-based models) seem to have standard pinouts for the external hard disk connector:
* Original model, Ace, Expert, Pro: Centronics 50-pin with /ATN, PARITY and Termination Power unconnected.
* Super, XVI: Standard Centronics 50-pin.
* Compact XVI, X68030, X68030 Compact: High-Density Centronics 50-pin.
All X68000 machines have a custom internal hard disk connector.
The pinout for the SASI-based machines is as follows:
| Pin | Description | Pin | Description |
|---|---|---|---|
| 1 | DB0 | 11 | GND |
| 2 | DB1 | 12 | Unknown(Possibly for the HD access LED) |
| 3 | GND | 13 | /BSY |
| 4 | DB2 | 14 | /ACK |
| 5 | DB3 | 15 | /RST |
| 6 | DB4 | 16 | /MSG |
| 7 | GND | 17 | /SEL |
| 8 | DB5 | 18 | /C/D |
| 9 | DB6 | 19 | REQ |
| 10 | DB7 | 20 | /I/O |
The pinout for SCSI-based machines(Taken from http://homepage1.nifty.com/ht_deko/x68ktune.html):
| Pin | Description | Pin | Description |
|---|---|---|---|
| 1 | DB0 | 14 | /ATN |
| 2 | DB1 | 15 | GND |
| 3 | GND | 16 | HD Access LED |
| 4 | DB2 | 17 | /BSY |
| 5 | DB3 | 18 | /ACK |
| 6 | DB4 | 19 | GND |
| 7 | GND | 20 | /RST |
| 8 | DB5 | 21 | /MSG |
| 9 | DB6 | 22 | /SEL |
| 10 | DB7 | 23 | GND |
| 11 | GND | 24 | /C/D |
| 12 | PARITY | 25 | /REQ |
| 13 | +5V(Termination power) | 26 | /I/O |
The HDD access LED is nonstandard and mapped to pin 34 of the 50-pin internal SCSI connector. Pulling it low turns on the HDD LED. Most standard SCSI HDDs connect this pin to ground, resulting in the HDD LED staying permanently on.