Hello, everyone, and it's time for a day of study. Let's talk about SDR, DDR, and QDR memory today.
Let's start with a brief look and then do a comparison.
SDR: Single Data Rate, Single Rate DDR: Dual Data Rate, Double Rate QDR: Quad Data Rate, Quadruple Rate
DRAM: Dynamic RAM, Dynamic Random Access Memory, Data is refreshed at regular intervals to save data SRAM: Static RAM, Static Random Access Memory, Static RAM, No refresh circuit, data is not lost SDRAM: Synchronous DRAM, Synchronization State RAM, data reads and writes require a clock to synchronize
Here's a comparison:
1, SRAM and DRAM, SDRAM, there is a DDR and QDR. QDR, DDR is just the rate, and has nothing to do with the distinction between DRAM/SRAM. And because of the process, DRAM and SDRAM are larger than SRAM, but read and write speeds are not as good as SRAM. In addition, they are generally applied to the RAM type of memory.
2. SDR transfers data only on the rising edge of the clock. Reading and writing is performed on the same data bus. Reading and writing cannot be performed at the same time. DDR is improved on the basis of SDR. It can be used when the clock rises and rises. Passing data once, which is equivalent to twice the SDR, but reading and writing can not be synchronized, and QDR, set read and write up and down transmission in one, to become a data interface with a forward, the equivalent of two DDR, four SDR can achieve the effect.
3, SRAM is actually a kind of very important memory, its use is extensive. SRAM is very fast and maintains data integrity during fast reads and refreshes. Internally, the SRAM uses a bistable circuit to store data. So the circuit structure of SRAM is very complicated. Manufacturing SRAM of the same capacity is much more expensive than DRAM. Because of this, its development has been limited. Therefore, at present, SRAM is basically used only in the CPU's internal cache and built-in secondary cache. Only a small number of network servers and routers can use SRAM.
4, the general embedded products inside the memory are used SDRAM, the computer's memory is also used SDRAM, called DDR SDRAM, its integration is very high, because it is dynamic, so there must be refresh the circuit, must be obtained from time to time Refresh the data.
Talk to you today, everyone, come on.
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