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Specialized DRAM chips, such as pseudostatic RAM (PSRAM), have all the refresh circuitry on the chip, and function like static RAM as far as the rest of the computer is concerned. [ 8 ] Usually the refresh circuitry consists of a refresh counter which contains the address of the row to be refreshed which is applied to the chip's row address ...
Address and control signals are still sent to the DRAM once per clock cycle (to be precise, on the rising edge of the clock), and timing parameters such as CAS latency are specified in clock cycles. Some less common DRAM interfaces, notably LPDDR2, GDDR5 and XDR DRAM, send commands and addresses using double data rate.
Memory clock then determines the final operating frequency or effective clock speed of memory system depending upon DRAM types (DDR, DDR2 and DDR3 SDRAM). By default, FSB speed and memory are usually set to a 1:1 ratio, meaning that increasing FSB speed (by overclocking ) increases memory speed by the same amount.
In the fields of digital electronics and computer hardware, multi-channel memory architecture is a technology that increases the data transfer rate between the DRAM memory and the memory controller by adding more channels of communication between them. Theoretically, this multiplies the data rate by exactly the number of channels present.
While the access latency of DRAM is fundamentally limited by the DRAM array, DRAM has very high potential bandwidth because each internal read is actually a row of many thousands of bits. To make more of this bandwidth available to users, a double data rate interface was developed. This uses the same commands, accepted once per cycle, but reads ...
Double data rate (DDR) memory controllers are used to drive DDR SDRAM, where data is transferred on both rising and falling edges of the system's memory clock.DDR memory controllers are significantly more complicated when compared to single data rate controllers, [citation needed] but they allow for twice the data to be transferred without increasing the memory's clock rate or bus width.
Memory bandwidth is the rate at which data can be read from or stored into a semiconductor memory by a processor.Memory bandwidth is usually expressed in units of bytes/second, though this can vary for systems with natural data sizes that are not a multiple of the commonly used 8-bit bytes.
DDR2 SDRAM was designed with such a scheme to avoid an excessive increase in power consumption. DDR2's bus frequency is boosted by electrical interface improvements, on-die termination, prefetch buffers and off-chip drivers. However, latency is greatly increased as a trade-off. The DDR2 prefetch buffer is four bits deep, whereas it is two bits ...