Early laptop memory was proprietary if you had an IBM laptop you needed IBM memory modules the same applied to other manufactures of laptop computers. This began to change and the industry through the PCMCIA group developed a form factor to make memory modules compatible to all the industries manufactures. The RAM used in laptops is either SO-DIMMS Small outline Dual inline memory module at a size of 68mm x 32mm, using 72 pin, 144 pin and 200 pin packages. The 72 pin package SO-DIMM was only 32 bits wide so it needed to be installed in pairs. The DDR3 uses a 204 pin package. The MicroDIMM, is about half the length of a SO-DIMM at a size of 45mm x 30mm, using a 64 bit data bus, and comes in 144 pin and 172 pin versions and a DDR2 214 pin package. If your laptop uses shared memory this is where the video card utilises part of the systems memory as in TurboCache developed by nVidia and HyperMemory by ATI. Laptop DIMMs also include a 68 pin DIMM package and 144 pin DIMM package, there was also a Rambus SO-RIMM 160 pin package.
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