Compared to single data rate (SDR) SDRAM, the DDR SDRAM interface makes higher transfer rates possible by more strict control of the timing of the electrical data and clock signals. Implementations often have to use schemes such as phase-locked loops and self-calibration to reach the required timing accuracy. The interface uses double pumping (transferring data on both the rising and falling edges of the clock signal) to double data bus bandwidth without a corresponding increase in clock frequency. One advantage of keeping the clock frequency down is that it reduces the signal integrity requirements on the circuit board connecting the memory to the controller. The name "double data rate" refers to the fact that a DDR SDRAM with a certain clock frequency achieves nearly twice the bandwidth of a SDR SDRAM running at the same clock frequency, due to this double pumping.
In addition to double pumping the data bus as in DDR SDRAM (transferring data on the rising and falling edges of the bus clock signal), DDR2 allows higher bus speed and requires lower power by running the internal clock at half the speed of the data bus. The two factors combine to produce a total of four data transfers per internal clock cycle.
Since the DDR2 internal clock runs at half the DDR external clock rate, DDR2 memory operating at the same external data bus clock rate as DDR results in DDR2 being able to provide the same bandwidth but with higher latency. Alternatively, DDR2 memory operating at twice the external data bus clock rate as DDR may provide twice the bandwidth with the same latency. The best-rated DDR2 memory modules are at least twice as fast as the best-rated DDR memory modules.
DDR3 is a DRAM interface specification. The actual DRAM arrays that store the data are similar to earlier types, with similar performance.
The primary benefit of DDR3 SDRAM over its immediate predecessor, DDR2 SDRAM, is its ability to transfer data at twice the rate (eight times the speed of its internal memory arrays), enabling higher bandwidth or peak data rates. With two transfers per cycle of a quadrupled clock signal, a 64-bit wide DDR3 module may achieve a transfer rate of up to 64 times the memory clock speed megahertz (MHz) in megabytes per second (MB/s). With data being transferred 64 bits at a time per memory module, DDR3 SDRAM gives a transfer rate of (memory clock rate) × 4 (for bus clock multiplier) × 2 (for data rate) × 64 (number of bits transferred) / 8 (number of bits/byte). Thus with a memory clock frequency of 100MHz, DDR3 SDRAM gives a maximum transfer rate of 6400 MB/s.
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When DDRSDRAM was released in 2000, it introduced the ability to transfer data on both the rise and fall of a single clock, which meant a DDR/400 module transferred more data but its actual internal clock speed was half that, at 200MHz.
To help achieve the cost, performance, size, and energy consumption requirements of its target applications, the MA35D0’s LQFP package, with 128MB or 256MB of stacked DDRSDRAM, significantly ...
Moreover they must, said Lowe, get companies to reveal the amounts they intended to charge for licensing patents which may be adopted in standards ... Broadcom ... The patents relate to SDRAM and DDRDRAM, but not to subsequent products like DDR2 and DDR3 ... .
* Learn more about megatransfers per second - MT/s denotes megatransfers (million transfers) per second and represents the effective data rate (speed) of DDR (Double Data Rate) SDRAM memory in computing.
We multiply this value by two (factor of two because DDR = Double Data Rate) and the number of past clock cycles, i.e ... A further increase in the data throughput of DDR SDRAM is provided by the so-called burst mode.
Learn more about megatransfers per second - MT/s denotes megatransfers (million transfers) per second and represents the effective data rate (speed) of DDR (Double Data Rate) SDRAM memory in computing.
1Learn more about megatransfers per second - MT/s denotes megatransfers (million transfers) per second and represents the effective data rate (speed) of DDR (Double Data Rate) SDRAM memory in computing.
Etron Technology's complete line of specialty DRAM products includes SDR, DDR, DDR2, DDR3, DDR4, LPDDR2, LPDDR4 SDRAM and SPINAND which provide densities ranging from 16Mb to 8Gb, number of I/O bits from 4 to 64 bits.
2Learn more about megatransfers per second - MT/s denotes megatransfers (million transfers) per second and represents the effective data rate (speed) of DDR (Double Data Rate) SDRAM memory in computing.
1Learn more about megatransfers per second - MT/s denotes megatransfers (million transfers) per second and represents the effective data rate (speed) of DDR (Double Data Rate) SDRAM memory in computing.
4Learn more about megatransfers per second - MT/s denotes megatransfers (million transfers) per second and represents the effective data rate (speed) of DDR (Double Data Rate) SDRAM memory in computing.
/ Optical drive included ... The 2002 machine came with a PowerPC G4 processor running at 1 GHz, an Nvidia GeForce4 MX, 256MB of DDRSDRAM running at 333 MHz, and an 80GB hard drive running at 7,200 rpm ... .
Image source. Connor55. The iMac G4 is ancient by now, but it hasn’t lost its charm ... It had a graphics card made by Nvidia no less, the GeForce4 MX, as well as a whopping 256MB of DDRSDRAM with a 333MHz frequency ... Image source. Connor55 ... ....
2Learn more about megatransfers per second - MT/s denotes megatransfers (million transfers) per second and represents the effective data rate (speed) of DDR (Double Data Rate) SDRAM memory in computing.
The Galveston Daily News
09 Oct 2023
The Galveston Daily News
09 Oct 2023