Small Outline DIMM definition storage
(SO-DIMM) A smaller kind of DIMM
with 72 pins (supporting 32-bit transfers) or 144 pins (64-bit transfers). Regular DIMMs have 168 pins and support 64-bit transfers. Being roughly half the size of the regular DIMM, SO-DIMMs are often used in notebook computers.
Kingston Memory Guide (http://kingston.com/tools/umg/newumg05a.asp).