What are the common kinds of memory used in PCs today?
All user-upgradeable memory in PCs these days is a variant of dynamic random access memory (DRAM). The most common types are Synchronous DRAM (SDRAM), Double Data Rate (DDR) SDRAM, and Rambus’ RDRAM. RAM has a maximum speed, like processors, and plugs into a set of signals in the computer called the front side bus. SDRAM produces data at the same speed as that bus and is named accordingly – PC100 is 100MHz, PC133 is 133 MHz and so on. DDR RAM produces two lots of data per Hz of bus speed, so is up to twice as fast for the same bus. RDRAM has a unique very high speed serial bus, and runs fastest of them all.
