144 pin SO DIMM DRAM
The 144-pin SO-DIMM (Small Outline Dual Inline Memory Module) is the compact, laptop-oriented equivalent of the full-size 168-pin SDRAM DIMM, standardised under JEDEC JESD21-C with mechanical outline MO-190. It provides a 64-bit synchronous DRAM data bus (72-bit with ECC) at 3.3 V, operating at up to 133 MHz (PC133), and was the dominant notebook memory format from approximately 1997 to 2002 before being superseded by DDR SO-DIMMs. The module carries the same Serial Presence Detect (SPD) EEPROM interface — accessed via I²C — as its full-size counterpart.
- SO = Small Outline
- DIMM = Dual Inline Memory Module
- DRAM = Dynamic Random Access Memory
| FRONT |
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| PIN |
| 1 |
| 3 |
| 5 |
| 7 |
| 9 |
| 11 |
| 13 |
| 15 |
| 17 |
| 19 |
| 21 |
| 23 |
| 25 |
| 27 |
| 29 |
| 31 |
| 33 |
| 35 |
| BACK |
|---|
| PIN |
| 2 |
| 4 |
| 6 |
| 8 |
| 10 |
| 12 |
| 14 |
| 16 |
| 18 |
| 20 |
| 22 |
| 24 |
| 26 |
| 28 |
| 30 |
| 32 |
| 34 |
| 36 |
(*) Pin 70 is No Connect for 32MB and 64MB modules, or A12 for 128MB modules.
Notes
- The 144-pin SO-DIMM uses JEDEC mechanical outline MO-190, with a 1.27 mm (50-mil) contact pitch on each side of the PCB edge.
- Odd-numbered pins appear on the front face; even-numbered pins appear on the back face.
- A notch (key) in the connector edge prevents insertion of 3.3 V SO-DIMMs into sockets intended for other voltages.
- Modules are available in unbuffered (UDIMM) configurations only; registered variants are not defined for the 144-pin SO-DIMM form factor.
- Pin 70 function depends on module capacity: No Connect on 32 MB and 64 MB modules; address line A12 on 128 MB modules.
- Serial Presence Detect (SPD) data is stored in an on-module EEPROM and accessed by the host system via the I²C bus.
- Both PC100 (100 MHz) and PC133 (133 MHz) speed grades are supported; CAS latency of 2 or 3 cycles is programmable via the Mode Register.
References
- JEDEC JESD21-C, Configurations for Solid State Memories — 144-pin SDRAM SO-DIMM family (module-455, module-456), mechanical outline MO-190. JEDEC Solid State Technology Association.