What is the difference between SDRAM and DDR

The specific differences between SDRAM and DDR are as follows:

1. There is a difference in transfer rate:

Traditional sdram can only transfer data at the rising edge of the signal, while ddr can only transfer data at the rising and falling edges of the signal, so ddr memory is twice as much as sdram for the amount of data transfer in each clock cycle, which is also the reason that ddr meaning of double data rate, double data rate.

2, the appearance of the slot there is a difference:

ddr in shape and size and sdram difference is small, they have similar size and pin pitch, the standard DDR memory module is a 184-pin DIMM (double-sided pin memory module). ddr and the standard 168-pin sdram is very similar to the biggest difference is that the ddr only use a slot, and the sdram uses two slots.

3. There are differences in design:

Compared to sdram, ddr uses more advanced synchronization circuits that make the major steps of specifying addresses and sending and outputting data not only independent, but also completely synchronized with the cpu.

DDR uses a delay-locked cycling technique that allows the memory controller to use this data filtering signal to precisely position data when it is valid, outputting it every 16th time and resynchronizing data from different memory modules.

Baidu encyclopedia-SDRAM

Baidu encyclopedia-DDR