RAM on the Motherboard. Memory is divided into two categories:ROM Read-Only Memory (last chapter)-- Retains data when PC is turned offRAM Random Access Memory-- Temporary storage loses data on shutdown. RAM on the Motherboard. Two Subcategories of RAM:DRAM (dynamic RAM) needs to be refreshed (computer must rewrite the data to the chip) by the memory controller (part of the chip set on the motherboard). Most DRAM is stored on DIMMs instead of RIMMs (will get to this later in the chapter)Dynamic = constantly changing!!.