IBM 5000 manual Shows the pin-number Assignments For 68-pin Scsi connectors

Table 8	shows the pin-number		assignments	for	the 68-pin SCSI connectors.
Table	8. The 68-Pin SCSI Port Connector Pin-Number Assignments
Pin	Signal		Pin	Signal
1	Ground		35	Data	12
2	Ground		36	Data	13
3	Ground		37	Data	14
4	Ground		38	Data	15
5	Ground		39	Data	P1
6	Ground		40	Data	0
7	Ground		41	Data	1
8	Ground		42	Data	2
9	Ground		43	Data	3
10	Ground		44	Data	4
11	Ground		45	Data	5
12	Ground		46	Data	6
13	Ground		47	Data	7
14	Ground		48	Data	P0
15	Ground		49	Reserved
16	Ground		50	-PRSN
17	Terminal	power	51	Terminal		power
18	Terminal	power	52	Terminal		power
19	Reserved		53	Reserved
20	Ground		54	Ground
21	Ground		55	-Attention
22	Ground		56	Ground
23	Ground		57	-Busy
24	Ground		58	-Acknowledge
25	Not connected		59	-Reset
26	Ground		60	-Message
27	Ground		61	-Select
28	Ground		62	-Control/Data
29	Ground		63	-Request
30	Ground		64	-Input/Output
31	Ground		65	Data	8
32	Ground		66	Data	9
33	Ground		67	Data	10
34	Ground		68	Data	11

Chapter 4. Installing Options89