What is the difference between DDR SDRAM and SDRAM?
DDR SDRAM is a straightforward evolution from current single data rate (SDR) SDRAM. DDR, which stands for Double Data Rate SDRAM, actually doubles the bandwidth available to your system and runs twice as fast as regular SDRAM. For example, 266MHz DDR SDRAM (133MHz doubled) has the bandwidth of 2.1GB/sec and is referred to as PC2100. The big difference between DDR SDRAM and standard SDRAM is that DDR reads data on both the rising and falling edges of the clock signal. Standard SDRAM, or single data rate (SDR) SDRAM, only carries information on the rising edge of a signal. Basically this allows the DDR module to transfer data twice as fast as SDR SDRAM. For example, instead of a data rate of 133MHz, DDR memory transfers data at 266MHz.
