Small outline dual in-line memory modules (SODIMMs) are much like the regular DIMM memory used in desktop PCs, but SODIMMS generally place chips in two rows so as to be narrower and more compact (6.76 x 3.175 cm). Over time, SODIMMs have been made in 72-, 100-, 144-, 200-, and 204-pin designs. DDR/DDR2 modules use the 200-pin format, and DDR3 is 204-pin. The edge connector notch (“key”) position varies across SODIMM types.