Piedinature - Pinouts
SCSI Internal (Single-ended)

Reference and Sources:

SCSI=Small Computer System Interface.
Based on an original design by Shugart Associates. SCSI was ratified in 1986.

(50 PIN IDC MALE at the controller & harddisk)

(50 PIN IDC FEMALE at the cable)

Pin	Name	Dir	Description
2	DB0	IN/OUT	Data Bus 0
4	DB1	IN/OUT	Data Bus 1
6	DB2	IN/OUT	Data Bus 2
8	DB3	IN/OUT	Data Bus 3
10	DB4	IN/OUT	Data Bus 4
12	DB5	IN/OUT	Data Bus 5
14	DB6	IN/OUT	Data Bus 6
16	DB7	IN/OUT	Data Bus 7
18	PARITY	IN/OUT	Data Parity (odd Parity)
20	GND	------	Ground
22	GND	------	Ground
24	GND	------	Ground
26	TMPWR	IN/OUT	Termination Power
28	GND	------	Ground
30	GND	------	Ground
32	/ATN	IN	Attention
34	GND	------	Ground
36	/BSY	IN/OUT	Busy
38	/ACK	IN	Acknowledge
40	/RST	IN/OUT	Reset
42	/MSG	OUT	Message
44	/SEL	IN/OUT	Select
46	/C/D	OUT	Control/Data
48	/REQ	OUT	Request
50	/I/O	OUT	Input/Output

Note: Direction is Device relative Bus (other Devices).

All odd-numbered pins, except pin 25, are connected to ground. Pin 25 is left open.

For more informations, references and sources go to

Piedinature - PinoutsSCSI Internal (Single-ended)