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The key difference between DDR2 and DDR SDRAM is the increase in prefetch length. In DDR SDRAM, the prefetch length was two bits for every bit in a word; whereas it is four bits in DDR2 SDRAM. During an access, four bits were read or written to or from a four-bit-deep prefetch queue.
9 wrz 2024 · DDR2 uses the same internal clock speed as DDR, however, the transfer rates are faster due to the enhanced input/output bus signal. DDR2 has a 4-bit prefetch, which is twice that of DDR. DDR2 can also reach data rates of 533 to 800MT/s. DDR2 memory can be installed in pairs to run in "dual channel mode," which can increase memory throughput ...
9 wrz 2024 · The DDR means "Double Data Rate" which means it transfers data on both the rising AND falling edges of the signal (instead of just signal on vs. off). So, for example, DDR gives you the effect of 800MHz while actually still only being at 400MHz.
5 maj 2023 · The lowest speed DDR3 RAM runs is 533MHz, which means a clock cycle of 1/533000000, or 1.87 ns. With a CAS latency of 7 cycles, the total latency is 1.87 x 7 = 13.09 ns. ("ns" stands for nanoseconds.)
28 lut 2012 · What does it mean? And what happened to DDR and DDR2? At its most basic, DDR3 is the current standard for system memory, aka RAM or, to get more specific, SDRAM.
The key difference between DDR and DDR2 is that in DDR2 the bus is clocked at twice the speed of the memory cells, so four words of data can be transferred per memory cell cycle. Thus, without speeding up the memory cells themselves, DDR2 can effectively operate at twice the bus speed of DDR.
Shown above is a pair of 256MB modules of DDR2 PC4300 RAM (533MHz) from Crucial memory. DDR2 modules have 240-pins, compared to the 184-pins of DDR, meaning they are not backwards compatible. DDR2-SDRAM is considered an evolutionary upgrade over existing DDR memory.
