===== X68000 Hard Disk =====

==== External HD connector ====

All X68000s (even the SASI-based models) seem to have standard pinouts for the external hard disk connector:

 * Original model, Ace, Expert, Pro: [[http://www.gamesx.com/hwb/co_ScsiExternalCentronics50.html|Centronics 50-pin]] with /ATN, PARITY and Termination Power unconnected.

 * Super, XVI: Standard [[http://www.gamesx.com/hwb/co_ScsiExternalCentronics50.html|Centronics 50-pin]].

 * Compact XVI, X68030, X68030 Compact: [[http://www.gamesx.com/hwb/co_ScsiExternalHiDSub.html|High-Density Centronics 50-pin]].

==== Internal HD connector ====

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.