DDR SDRAM

__NOTOC__

~ ~ ~ ~ ~ ~ ~ ~ ~ ~

DDR SDRAM or double-data-rate synchronous dynamic random access memory is a type of memory integrated circuit used in computers. It achieves greater bandwidth than ordinary 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 retroactive 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.

~ ~ ~ ~ ~ ~ ~ ~ ~ ~

Dynamic random access memory: DRAM is a type of random access memory that stores each bit of data in a separate capacitor....

Integrated circuit: An integrated circuit (IC) is a thin chip consisting of at least two interconnected semiconductor devices, mainly transistors, as well as passive components like resistors. As of 2004, typical chips are of size 1 cm2 or smaller, and contain millions of interconnected devices, but larger ones exist a...

Computer: A computer is a device or for processing information from data according to a program — a compiled list of instructions. The information to be processed may represent numbers, text, pictures, or sound, amongst many other types....