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DDR — Double Data Rate . Here is a quote from the wiki:
When using DDR SDRAM, double the speed of operation is achieved than in SDRAM, due to the reading of commands and data not only along the front, as in SDRAM, but also along the decay of the clock signal. This doubles the data transfer rate without increasing the clock frequency of the memory bus. Thus, when DDR is running at a frequency of 100 MHz, we will get an effective frequency of 200 MHz (when compared with the SDR analog SDRAM). In the JEDEC specification[2] there is a remark that it is incorrect to use the term "MHz" in DDR, it is correct to indicate the speed of "millions of transmissions per second through one data output". |
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