what is ddr stand for ?

Answer 1

Double-Data-Rate Synchronous Dynamic Random Access Memory, better known as DDR SDRAM or DDR RAM for short, is a type of very fast computer memory. DDR RAM is based on the same architecture as SDRAM, but utilizes the clock signal differently to transfer twice the data in the same amount of time.

Answer 2

double-data-rate synchronous dynamic random access memory
is a type of memory integrated circuit used in computers. It achieves greater bandwidth than the preceding single-data-rate SDRAM by transferring data on both the rising and falling edges of the clock signal (double pumped). This effectively nearly doubles the transfer rate without increasing the frequency of the front side bus. Thus a 100 MHz DDR system has an effective clock rate of 200 MHz when compared to equivalent SDR SDRAM, the “SDR” being a retrospective designation.

With data being transferred 8 bytes at a time DDR RAM gives a transfer rate of (memory bus clock rate) × 2 (for dual rate) × 8 (number of bytes transferred). Thus with a bus frequency of 100 MHz, DDR-SDRAM gives a max transfer rate of 1600 MB/s.

JEDEC has set standards for speeds of DDR SDRAM, divided into two parts: The first specification is for memory chips and the second is for memory modules.

As DDR is superseded by the newer DDR2, the older version is often now referred to as DDR1.

DDR (DDR1) is now being superseded by DDR2 SDRAM, which has some modifications to allow higher clock frequency, but operates on the same principle as DDR. Competing with DDR2 are Rambus XDR-DRAM. DDR2 has become the standard, since QDR (Quad Data Rate) is too complex to affordably implement, while XDR is lacking support.

DDR Prefetch buffer width is 2 bits, DDR2 uses 4 bits. Although the effective clock speeds of DDR2 are higher than for DDR, the overall performance was no greater in the early implementations, primarily due to the high latencies of the first DDR2 modules. DDR2 started to be effective by the end of 2004, as modules with lower latencies became available.[1]

Memory manufacturers have stated that it is impractical to mass-produce DDR1 memory with effective clock rates in excess of 400 MHz. DDR2 picks up where DDR1 leaves off, and is available at clock rates of 400 MHz and higher.

RDRAM is a particularly expensive alternative to DDR SDRAM, and most manufacturers have dropped its support from their chipsets.

Answer 3

Dance Dance Revolution

Answer 4

Dance Dance Revolution, it is the video game where you have a dancing mat and have to step on the correct arrows by the beat in order to get a good score. It's fun and a definite calorie burner.

Answer 5

Double data rate

Answer 6

http://en.wikipedia.org/wiki/DDR_SDRAM

or this

http://en.wikipedia.org/wiki/Dance_Dance_Revolution