DDR memory, PC2100 (DDR266), PC2700 (DDR333), PC3200 (DDR400), PC4200 (DDR533). A quick look at DDR memory, what is DDR memory ? what some of the terms mean & which DDR memory to buy?
What is DDR Memory?
DDR memory is the latest in high-performance memory module technological advances. It offers twice the data bandwidth of conventional PC100 or PC133 SDRAM, and is particularly well suited for high-performance servers and workstations, which need optimal CPU-memory performance. Double Data Rate (DDR) SDRAM (AKA SDRAMII) is precisely what the name implies. A clock cycle can be represented as a square wave, with the rising edge defined as the transition from "0" to "1", and the falling edge as "1" to "0". In SDRAM, only one of these wave edges is used, but DDR SDRAM references both, effectively doubling the rate of data transmission. Unlike 168-pin SDRAM, DDR SDRAM utilizes a 184-pin plug. Although the basic motherboard technology does not need to be changed, DDR SDRAM is not backward compatible on motherboards designed for SDRAM.
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DDR memory can only be used in systems designed specifically for DDR memory
DDR Memory terms explained
What is DDR memory CAS Latency?
CAS Latency is the time needed (clock cycles) to address the data column. CAS is the Column Address Strobe. Thus CL2.5 is quicker than CL3. (2.5 < 3) But, once the first piece of data is processed the rest of the data is processed at equal speeds. Latency only affects the initial burst or fetch of data.RAS is the Row Address Strobe. Abbreviated RAS, a signal, or strobe, sent by the processor to a DRAM circuit to activate a row address. DRAM stores data in a series of rows and columns, similar in theory to a spreadsheet, and each cell where a data bit is stored exists in both a row and a column. A processor uses RAS and CAS (column address strobe) signals to retrieve data from DRAM. When data is needed, the processor activates the RAS line to specify the row where the data is needed, and then activates the CAS line to specify the column. Combined, the two signals locate the data stored in DRAM.
What is DDR memory?
Why DDR Memory? What DDR Memory to buy?RAM Influence on Computer Performance
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