Information About DDR2
The ddr2 is the latest version of ddr. The fullform of ddr2 is double data rate interface. So both ddr andddr2 are not copatible in their own way. With
respect of double pumping the data bus in ddr and ddr2 uses I/O buffer between memory and data bus. As a result the data bus plays with doube
speed than the memory clock. So the combination of ddr and ddr2 collects four data transfers for each memory clock cycle.
so ddr2 reflects 3200MB/s which is the highest transfer rate at present. On the same external data bus clock rate on which ddr 2 is working gives the
same bandwidth but iwth greater latency, giving inferior performance output. Now the good-rated ddr2 memory module are double fast in comparison
to ddr memory modules. Actually ddr2 keeps its memory in memory cells which got acitve by the usages of clock signals which helps in synchronizing
their work with the aid of external data bus. So ddr2 cells move the data on both rising and falling edges of the clock.
In this way ddr2 works very efficiently in comparison to data rate of ddr. The frequency of ddr2 bus is boosted by the usage of electrical interface
improvements, prefetch buffers, on-die termination and also off-chip drivers. The latencyis marketed quite high. Now the 4 bits deep is considered for
ddr2 prefetch buffer , for ddr 2 bits deep and for ddr3 8 bit deep is considered. At present ddr2 is carrying 4 to 6 cycles latencies. So in this way the
ddr2 memory should work on double data rate to get the same latency.
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To read about ddr2 and other information, visit the ram site.