Internal SCSI Port (50-Pin Header)
External SCSI Connector (High-density 50-pin) See External
SCSI Connector.
All odd pins are grounds, except for pin 25, which is unused.
Pin 2: *Data 0
Pin 4: *Data 1
Pin 6: *Data 2
Pin 8: *Data 3
Pin 10: *Data 4
Pin 12: *Data 5
Pin 14: *Data 6
Pin 16: *Data 7
Pin 18: *Parity
Pin 20: Ground
Pin 22: Ground
Pin 24: Ground
Pin 26: Terminator Power
Pin 28: Ground
Pin 30: Ground
Pin 32: *ATN
Pin 34: Ground (Unused?)
Pin 36: *BSY
Pin 38: *ACK
Pin 40: *RST
Pin 42: *MSG
Pin 44: *SEL
Pin 46: *C/D
Pin 48: *REQ
Pin 50: *I/O
External SCSI Connector (DB25 Macintosh-Type Female Pseudo-SCSI)
(Note: This is by far the most common style of DB25 SCSI connector.
Most [probably all] Amiga SCSI interfaces with DB25 connectors--like the
A2091--use this pin-out.)
Pin 1: *REQ
Pin 2: *MSG
Pin 3: *I/O
Pin 4: *RST
Pin 5: *ACK
Pin 6: *BSY
Pin 7: Ground
Pin 8: *Data 0
Pin 9: Ground
Pin 10: *Data 3
Pin 11: *Data 5
Pin 12: *Data 6
Pin 13: *Data 7
Pin 14: Ground
Pin 15: *C/D
Pin 16: Ground
Pin 17: *ATN
Pin 18: Ground
Pin 19: *SEL
Pin 20: *Parity
Pin 21: *Data 1
Pin 22: *Data 2
Pin 23: *Data 4
Pin 24: Ground
Pin 25: Terminator Power
External SCSI Connector (DB25 Future Domain-Type Female Pseudo-SCSI)
(Note: This is a rare alternate standard for the DB25 connector. It
was only used on the Future Domain TMC-830/845 and TMC-850/860/885, and
is included here in case you end up with a cable meant for these boards.)
Pin 1: Ground
Pin 2: *Data 1
Pin 3: *Data 3
Pin 4: *Data 5
Pin 5: *Data 7
Pin 6: Ground
Pin 7: *SEL
Pin 8: Ground
Pin 9: Terminator Power
Pin 10: *RST
Pin 11: *C/D
Pin 12: *I/O
Pin 13: Ground
Pin 14: *Data 0
Pin 15: *Data 2
Pin 16: *Data 4
Pin 17: *Data 6
Pin 18: *Parity
Pin 19: Ground
Pin 20: *ATN
Pin 21: *MSG
Pin 22: *ACK
Pin 23: *BSY
Pin 24: *REQ
Pin 25: Ground
External SCSI Connector (Centronics 50-Pin Female)
Pins 1-12 and 14-25 are grounds.
Pin 26: *Data 0
Pin 27: *Data 1
Pin 28: *Data 2
Pin 29: *Data 3
Pin 30: *Data 4
Pin 31: *Data 5
Pin 32: *Data 6
Pin 33: *Data 7
Pin 34: *Parity
Pin 35: Ground
Pin 36: Ground
Pin 37: Ground
Pin 38: Terminator Power
Pin 39: Ground
Pin 40: Ground
Pin 41: *ATN
Pin 42: Ground (Unused?)
Pin 43: *BSY
Pin 44: *ACK
Pin 45: *RST
Pin 46: *MSG
Pin 47: *SEL
Pin 48: *C/D
Pin 49: *REQ
Pin 50: *I/O
2.5-Inch Drive SCSI Connector (40-Pin Header)
Pins 1, 2, 39, and 40 are +5V. Pins 3, 4, 37, and 38 are ground returns for the +5V supply. Pins 5, 7, 9, 11, 13, 15, 19, 21, 23, 27, 31, and 35 are signal grounds. Pin 17 is used as a connector key and should not be present.
Pin 6: *Data 0
Pin 8: *Data 1
Pin 10: *Data 2
Pin 12: *Data 3
Pin 14: *Data 4
Pin 16: *Data 5
Pin 18: *Data 6
Pin 20: *Data 7
Pin 22: *Parity
Pin 24: Terminator Power
Pin 25: *ATN
Pin 26: *BSY
Pin 28: *ACK
Pin 29: *RST
Pin 30: *MSG
Pin 32: *SEL
Pin 33: *I/O
Pin 34: *C/D
Pin 36: *REQ