SCSI Internal (Single-ended) connector

#Computer#Harddisk interfaces

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

50 pin IDC MALE connector pin-out & layout

50 pin IDC MALE connector  at the controller & harddisk

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

SCSI Internal (Differential) connector

SCSI-II External Hi D-Sub (Differential) connector