Types of DDR Memories There are presently three generations of DDR memories: DDR1 memory, with a maximum rated clock of 400 MHz and a 64-bit (8 bytes) data bus is now becoming obsolete and is not being produced in massive quantities. Technology is adopting new ways to achieve faster speeds/data rates for RAM memories. DDR2 technology is replacing DDR with data rates from 400 MHz to 800 MHz and a data bus of 64 bits (8 bytes). Widely produced by RAM manufacturers, DDR2 memory is physically incompatible with the previous generation of DDR memories. DDR3 technology picks up where DDR2 left off (800 Mbps bandwidth) and brings the speed up to 1.6 Gbps. One of the chips already announced by ELPIDA contains up to 512 megabits of DDR3 SDRAM, with a column access time of 8.75 ns (CL7 latency) and data transfer rate of 1.6 Gbps at 1.6 GHz. The 1.5V DDR3 voltage level also saves some power compared to DDR2 memory. What is more interesting is that at an even lower 1.36V, the DDR3 RAM runs ...