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IBM SCSI Pinouts

Internal 50-pin Card-Edge Connector
Internal 50-pin Header Connector
External 60-pin Connector
Internal/External 68-pin Connector
External 50-pin Connector
Sources

Internal 50-pin Card-Edge Connector

Used on most IBM SCSI adapters to connect internal devices (narrow; 8-bit).

Pin	Signal	Pin	Signal
1	Ground	2	-Data 0
3	Ground	4	-Data 1
5	Ground	6	-Data 2
7	Ground	8	-Data 3
9	Ground	10	-Data 4
11	Ground	12	-Data 5
13	Ground	14	-Data 6
15	Ground	16	-Data 7
17	Ground	18	-Data Parity
19	Ground	20	Ground
21	Ground	22	Ground
23	Ground	24	Ground
25	Not Connected	26	+Terminal Power

27	Ground	28	Ground
29	Ground	30	Ground
31	Ground	32	-Attention
33	Ground	34	Ground
35	Ground	36	-Busy
37	Ground	38	-Acknowledge
39	Ground	40	-Reset
41	Ground	42	-Message
43	Ground	44	-Select
45	Ground	46	-Control/Data
47	Ground	48	-Request
49	Ground	50	-Input/Output

Pin 1 is located on the solder side of the PCB, closer to the rear metal bracket.

There is a physical key between pins 25 and 27 (26 and 28).

On the "Tribble" PCB the odd pins 1-49 are marked as BB01-BB25 (solder side) and even pins 2-50 as AA01-AA25 (component side).

Internal 50-pin Header Connector

This is the "industry standard" internal SCSI connector (narrow; 8-bit). It's used by all planar SCSI implementations and also by the following adapters:

IBM SCSI-2 Adapter ("Patriot"; OEM Future Domain)
2/3 Length IBM SCSI/A
2/3 Length IBM SCSI w/ Cache

Pin	Signal	Pin	Signal
1	Ground	2	-Data 0
3	Ground	4	-Data 1
5	Ground	6	-Data 2
7	Ground	8	-Data 3
9	Ground	10	-Data 4
11	Ground	12	-Data 5
13	Ground	14	-Data 6
15	Ground	16	-Data 7
17	Ground	18	-Data Parity
19	Ground	20	Ground
21	Ground	22	Ground
23	Ground	24	Ground
25	Not Connected	26	+Terminal power
27	Ground	28	Ground
29	Ground	30	Ground
31	Ground	32	-Attention
33	Ground	34	Ground
35	Ground	36	-Busy
37	Ground	38	-Acknowledge
39	Ground	40	-Reset
41	Ground	42	-Message
43	Ground	44	-Select
45	Ground	46	-Control/Data
47	Ground	48	-Request
49	Ground	50	-Input/Output

External 60-pin Connector

60-pin Mini Centronics

This is the 60-pin Mini Centronics connector used on most narrow IBM SCSI adapters to connect external devices.

Pin	Signal	Pin	Signal
1	Ground	31	Ground
2	-Data 0	32	-Attention
3	Ground	33	Ground
4	-Data 1	34	Ground
5	Ground	35	Ground
6	-Data 2	36	-Busy
7	Ground	37	Ground
8	-Data 3	38	-Acknowledge
9	Ground	39	Ground
10	-Data 4	40	-Reset
11	Ground	41	Ground
12	-Data 5	42	-Message
13	Ground	43	Ground
14	-Data 6	44	-Select
15	Ground	45	Ground
16	-Data 7	46	-Control/Data
17	Ground	47	Ground
18	-Data Parity	48	-Request
19	Ground	49	Ground
20	Ground	50	-Input/Output
21	Ground	51	Ground
22	Ground	52	Reserved / Ground**
23	Ground	53	Reserved / Ground**
24	Ground	54	Reserved / Ground**
25	Not Connected	55	Reserved / Ground**
26	+Terminal Power (+5 V fused)	56	Reserved / Ground**
27	Ground	57	Reserved / Ground**
28	Ground	58	Reserved / Ground* / Ground**
29	Ground	59	Reserved / 8032 RXD* / Ground**
30	Ground	60	Reserved / 8032 TXD* / Ground**

Notes:
* Applies to uncached SCSI/A adapters
** Applies to SCSI w/ cache adapters

Pin 59 and 60 are used to access the Serial Console on the uncached adapters.

Internal/External 68-pin Connector

68-pin Mini Centronics

This is the 68-pin Mini Centronics connector used on most fast/wide IBM SCSI adapters to connect internal and external devices (the two variants use similar connectors but the internal one lacks the metal shielding).

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 Parity 1
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 Parity 0
15	Ground	49	Ground
16	Ground	50	Ground
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	Ground	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

External 50-pin Connector

50-pin Mini D-Sub

This is the "industry standard" HPDB50 external SCSI connector (narrow; 8-bit). It's used by a very few IBM SCSI adapters:

IBM SCSI-2 Adapter ("Patriot"; OEM Future Domain)

Pin	Signal	Pin	Signal
1	Ground	26	-Data 0
2	Ground	27	-Data 1
3	Ground	28	-Data 2
4	Ground	29	-Data 3
5	Ground	30	-Data 4
6	Ground	31	-Data 5
7	Ground	32	-Data 6
8	Ground	33	-Data 7
9	Ground	34	-Data Parity
10	Ground	35	Ground
11	Ground	36	Ground
12	Reserved	37	Reserved
13	Not Connected	38	+Terminal power
14	Reserved	39	Reserved
15	Ground	40	Ground
16	Ground	41	-Attention
17	Ground	42	Ground
18	Ground	43	-Busy
19	Ground	44	-Acknowledge
20	Ground	45	-Reset
21	Ground	46	-Message
22	Ground	47	-Select
23	Ground	48	-Control/Data
24	Ground	49	-Request
25	Ground	50	-Input/Output

Sources

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