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Memory Module Pinouts

30-pin IBM SIMM Memory
72-pin IBM SIMM Memory

30-pin IBM SIMM Memory

Pin	Signal
1	+5 Vdc
2	-Column Address Strobe
3	Data 0
4	Address 0
5	Address 1
6	Data 1
7	Address 2
8	Address 3
9	Ground
10	Data 2
11	Address 4
12	Address 5
13	Data 3
14	Address 6
15	Address 7
16	Data 4
17	Address 8
18	N/C or Address 9 ¹⁾
19	-Row Address Strobe 1
20	Data 5
21	-Write Enable (-Write Strobe)
22	Ground
23	Data 6
24	Presence Detect 1
25	Data 7
26	Presence Detect 2
27	-Row Address Strobe 0
28	N/C or -Column Address Strobe ²⁾
29	Parity Data In/Out
30	+5 Vdc

Notes:
1) Except for Model 30 (8086) planar memory sockets? (unconfirmed)
2) Model 30 (8086) planar memory sockets only? (duplicate signal; unconfirmed)

References:

PS/2 Model 50 Technical Reference (page 41 physical)
PS/2 Model 60 Technical Reference (page 41 physical)
PS/2 Model 50 Schematics (sheet 3 physical)
PS/2 Model 30 Schematics (sheet 3 physical)
PS/2 Model 30-286 Schematics (sheet 1 physical)

72-pin IBM SIMM Memory

Pin	Signal	Pin	Signal
1	Ground	37	Parity 1/Data 36 ²⁾
2	Data 0	38	Parity 3/Data 38 ²⁾
3	Data 16	39	Ground
4	Data 1	40	Column Address Strobe 0
5	Data 17	41	Column Address Strobe 2
6	Data 2	42	Column Address Strobe 3
7	Data 18	43	Column Address Strobe 1
8	Data 3	44	Row Address Strobe 0
9	Data 19	45	Row Address Strobe 1
10	+5 Vdc	46	Block Select 1/Data 33 ²⁾
11	-Column Address Strobe Parity	47	Write Enable
12	Address 0	48	Reserved/Ground ²⁾
13	Address 1	49	Data 8
14	Address 2	50	Data 24
15	Address 3	51	Data 9
16	Address 4	52	Data 25
17	Address 5	53	Data 10
18	Address 6	54	Data 26
19	Reserved/Address 10 ¹⁾	55	Data 11
20	Data 4	56	Data 27
21	Data 20	57	Data 12
22	Data 5	58	Data 28
23	Data 21	59	+5 Vdc
24	Data 6	60	Data 29
25	Data 22	61	Data 13
26	Data 7	62	Data 30
27	Data 23	63	Data 14
28	Address 7	64	Data 31
29	Block Select 0/Data 32 ²⁾	65	Data 15
30	+5 Vdc	66	Block Select 2/Data 34 ²⁾
31	Address 8	67	Presence Detect 0
32	Reserved/Address 9 ³⁾	68	Presence Detect 1
33	Row Address Strobe 3	69	Presence Detect 2
34	Row Address Strobe 2	70	Presence Detect 3
35	Parity 2/Data 37 ²⁾	71	Block Select 3/Address 11 ¹⁾ ²⁾
36	Parity 0/Data 35 ²⁾	72	Ground

Notes:
   1) Late systems only (Model 85 Type 2, Model 76/77 i/s).
   2) Late systems only (Model 95, Model 76/77 i/s). Used only with ECC memory.
   3) All except early systems (Model 50, 70, P70).

References:

PS/2 Model 50 Technical Reference (page 42 physical)
PS/2 Model 55 Technical Reference (page 42 physical)
PS/2 Model 65 SX Technical Reference (page 43 physical)
PS/2 Model 70 Technical Reference (page 72 physical)
PS/2 Model P70 Technical Reference (page 56 physical)
PS/2 Model 90 XP 486 Technical Reference (page 40 physical)
PS/2 Model 95 XP 486 Technical Reference (page 36 physical)
PS/2 Servers 95 and 95A Technical Reference
PS/2 Server 85 Technical Reference
PS/2 76i, 76s, 77i and 77s Technical Reference

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Last update: 30 Jul 2023 - Changelog | Legal Info & Contact