DIMM

Dual In-Line Memory Module: a small circuit board that holds memory chips a single in-line memory module (SIMM) has a 32-bit path to the memory chips whereas a DIMM has 64-bit path. Because the Pentium processor requires a 64-bit path to memory, you need to install SIMMs two at a time. With DIMM’s, you can install memory one DIMM at a time.