168 pin DRAM DIMM (Unbuffered) Pinout

Personal Computer Memory Module description, 168-pin DIMM Pin out.
This was a memory module [memory stick] used with Desk-top computers
The 168-pin DIMM have 84 pins per PWB side.
The Front Side board pinout contains left side pins 1-42, and right side pins 43-84.
The Back Side board pin out has left side pins 85-126, and right side pins 127-168.
168-pin DIMM memory modules would be found in Desktop computers.

Front, Left Side Signals

168-Pin SDRAM DIMM PinOut
Pin # Non-Parity Parity 72 ECC 80 ECC Pin Description
2 DQ0 DQ0 DQ0 DQ0 Data 0
3 DQ1 DQ1 DQ1 DQ1 Data 1
4 DQ2 DQ2 DQ2 DQ2 Data 2
5 DQ3 DQ3 DQ3 DQ3 Data 3
6 VCC VCC VCC VCC +5 VDC or +3.3 VDC
7 DQ4 DQ4 DQ4 DQ4 Data 4
8 DQ5 DQ5 DQ5 DQ5 Data 5
9 DQ6 DQ6 DQ6 DQ6 Data 6
10 DQ7 DQ7 DQ7 DQ7 Data 7
11 DQ8 DQ8 DQ8 DQ8 Data 8
13 DQ9 DQ9 DQ9 DQ9 Data 9
14 DQ10 DQ10 DQ10 DQ10 Data 10
15 DQ11 DQ11 DQ11 DQ11 Data 11
16 DQ12 DQ12 DQ12 DQ12 Data 12
17 DQ13 DQ13 DQ13 DQ13 Data 13
18 VCC VCC VCC VCC +5 VDC or +3.3 VDC
19 DQ14 DQ14 DQ14 DQ14 Data 14
20 DQ15 DQ15 DQ15 DQ15 Data 15
21 CB0 CB0 CB0 CB0 Parity/Check Bit Input/Output 0
22 CB1 CB1 CB1 CB1 Parity/Check Bit Input/Output 1
24 NC NC NC CB8 Parity/Check Bit Input/Output 8
25 NC NC NC CB9 Parity/Check Bit Input/Output 9
26 VCC VCC VCC VCC +5 VDC or +3.3 VDC
27 /WE0 /WE0 /WE0 /WE0 Read/Write Input
28 /CAS0 /CAS0 /CAS0 /CAS0 Column Address Strobe 0
29 /CAS1 /CAS1 /CAS1 /CAS1 Column Address Strobe 1
30 /RAS0 /RAS0 /RAS0 /RAS0 Row Address Strobe 0
31 /OE0 /OE0 /OE0 /OE0 Output Enable
33 A0 A0 A0 A0 Address 0
34 A2 A2 A2 A2 Address 2
35 A4 A4 A4 A4 Address 4
36 A6 A6 A6 A6 Address 6
37 A8 A8 A8 A8 Address 8
38 A10 A10 A10 A10 Address 10
39 A12 A12 A12 A12 Address 12
40 VCC +5 VDC or +3.3 VDC
41 VCC +5 VDC or +3.3 VDC
42 NC NC NC NC No Connection

Front, Right Side Signals

168-Pin SDRAM DIMM PinOut
Pin # Non-Parity Parity 72 ECC 80 ECC Pin Description
44 /OE2 /OE2 /OE2 /OE2  
45 /RAS2 /RAS2 /RAS2 /RAS2 Row Address Strobe 2
46 /CAS2 /CAS2 /CAS2 /CAS2 Column Address Strobe 2
47 /CAS3 /CAS3 /CAS3 /CAS3 Column Address Strobe 3
48 /WE2 /WE2 /WE2 /WE2 Read/Write Input
49 VCC +5 VDC or +3.3 VDC
50 NC NC NC CB10 Parity/Check Bit Input/Output 10
51 NC NC NC CB11 Parity/Check Bit Input/Output 11
52 NC CB2 CB2 CB2 Parity/Check Bit Input/Output 2
53 NC CB3 CB3 CB3 Parity/Check Bit Input/Output 3
54 VSS Ground
55 DQ16 DQ16 DQ16 DQ16 Data 16
56 DQ17 DQ17 DQ17 DQ17 Data 17
57 DQ18 DQ18 DQ18 DQ18 Data 18
58 DQ19 DQ19 DQ19 DQ19 Data 19
59 VCC +5 VDC or +3.3 VDC
60 DQ20 DQ20 DQ20 DQ20 Data 20
61 NC No Connection
62 NC No Connection
63 NC No Connection
64 VSS Ground
65 DQ21 DQ21 DQ21 DQ21 Data 21
66 DQ22 DQ22 DQ22 DQ22 Data 22
67 DQ23 DQ23 DQ23 DQ23 Data 23
69 DQ24 DQ24 DQ24 DQ24 Data 24
70 DQ25 DQ25 DQ25 DQ25 Data 25
71 DQ26 DQ26 DQ26 DQ26 Data 26
72 DQ27 DQ27 DQ27 DQ27 Data 27
73 VCC +5 VDC or +3.3 VDC
74 DQ28 DQ28 DQ28 DQ28 Data 28
75 DQ29 DQ29 DQ29 DQ29 Data 29
76 DQ30 DQ30 DQ30 DQ30 Data 30
77 DQ31 DQ31 DQ31 DQ31 Data 31
78 VSS Ground
79 NC No Connection
80 NC No Connection
81 NC No Connection
82 SDA Serial Data
83 SCL Serial Clock
84 VCC +5 VDC or +3.3 VDC

In order to keep this page at a reasonable size, refer here for the pin out of Rear side 168-pin DIMM pin out.
The pin out above relates to the front-side of a 168-pin DIMM, the side with the memory ICs.
These memory sticks are basically two-sided printed circuit boards, with copper fingers on each side.

Data width is 64 bits per memory stick [the front side 84 pins are not connected together with the back side 84 pins]

168 Pin DIMM Memory Module Picture
The approximate board size. 5.375" x 1.375"

DRAM: Dynamic Random Access Memory
SDRAM:: Synchronous DRAM (Random Access Memory), Synchronous to Positive Clock Edge.
FPM:Fast Page Mode: (asynchronous) Obsolete, faster than normal DRAM, used in 386/486 computers.
EDO: Extended Data Out: (asynchronous) A superset of FPM, just faster than FPM.
All 168 pin DIMMs use either 66MHz SDRAM, PC100 SDRAM, PC133 SDRAM, EDO or FPM memory. 168 pin DIMMs have two alignment notches as shown.
The left most notch [keyway] determines the DRAM type. If the notch is centered then the memory module is Buffered DRAM [EDO or Fast Page].
If the notch is off-set to the right then the memory module is either a un-buffered DRAM/SDRAM DIMM or a buffered SDRAM DIMM.
The center notch determines the voltage. If the notch is centered then the DIMM operates off 3.3 volts.

Additional electronic Equipment manufacturers may be found by selecting the OEM Equipment icon below,
or component manufacturers may be found by selecting the Components icon below.
Back to the main Computer Memory Modules information page. For electronic device manufacturers see one of these pages:
Memory IC manufacturers [IC memory vendors]
Memory Module manufacturers [memory stick vendors]
Memory Module Acronyms [specific to memory sticks]
IC Memory Acronyms [specific to memory ICs]

Editor note; This family of memory module was used with desk-top computers, lap-top computers would use a different style.
This particular generation of memory module was used in computers before the advent of DDR memory, and is slower than DDR.
Because the DDR style is faster, that implies that this format, or memory stick implementation is out-dated and should no longer be used.
However given the long-life of military systems, these memory module could still be in use.
Regardless of the fact that memory format being out-dated, the board pin-outs are still valid.
You could also conclude that this family is fixed in time and will not be changing, given the fact that a new family of modules has replaced it.
In other words, work on this standard of memory modules is probably no longer on-going.
Newer memory stick formats are not compatible and are designed not to plug into a 168-pin memory stick socket.

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Modified 6/13/15
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