DDR-SDRAM Has Finally Arrived

Information about RAM (SDR and DDR)

http://computing-dictionary.thefreedictionary.com

(Random Access Memory) A group of memory chips, typically of the dynamic RAM (DRAM) type, which function as the computer's primary workspace. When personal computers first came on the market in the late 1970s, 64KB (64 kilobytes) of RAM was the upper limit. Today, 64MB (64 megabytes) of SDRAM is entry level for a desktop computer, a thousand times as much (see SDRAM).

The "random" in RAM means that the contents of each byte of storage in the chip can be directly accessed without regard to the bytes before or after it. This is also true of other types of memory chips, including ROMs and PROMs. However, unlike ROMs and PROMs, RAM chips require power to maintain their content, which is why you must save your data onto disk before you turn the computer off. To learn about the types of RAM chips and how to upgrade your memory, see memory module. To learn how memory is used to process data, see computer or memory. See also dynamic RAM and static RAM.

(Synchronous DRAM) A type of DRAM memory chip that has been widely used since the latter part of the 1990s. SDRAM chips eliminate wait states because they are fast enough to be synchronized with the CPU's clock. The chip is divided into two cell blocks, and data are interleaved between the two. While a bit in one block is accessed, a bit in the other is prepared for access. This allows SDRAM to burst subsequent, contiguous characters at a much faster rate than the first character.

DDR and DDR2 Double Data Rate SDRAM (DDR) doubles transfer rates by transferring data on both the rising and falling edges of the clock. DDR uses additional power and ground lines and is packaged on a 184-pin DIMM module rather than the 168-pin DIMM used by the first SDRAM chips. Laptops use 200-pin SODIMM modules.

DDR2 chips increase data rates using various techniques such as on-die termination, which places the terminating transistors that eliminate excess signal noise on the chip itself. DDR2 modules require 240-pin DIMM slots, and although they are the same length as DDR, they are keyed differently and will not fit into the DDR slot.

Dual Channel DDR and DDR2 Chipsets on the motherboard may support two independent memory controllers, which allow access to two memory modules simultaneously (upstream data on one 64-bit channel; downstream data on the other). Channels can be configured as two 64-bit or one 128-bit. Modules must be installed in matched pairs unless the chipset has an option for mismatched modules. See memory module and SGRAM.

SDR RAM

Single Data Rate Random Access Memory - (SDR-RAM, SDR-SDRAM, Single Data Rate Synchronous Dynamic Random Access Memory) RAM or SDRAM that transfers data on only one clock transition (0-1 or 1-0), in contrast to DDR-RAM.

DDR RAM

Double Data Rate Random Access Memory - (DDR-RAM, DDR-SDRAM ...Synchronous...) RAM that transfers data on both 0-1 and 1-0 clock transitions, theoretically yielding twice the data transfer rate of normal RAM or SDRAM. DDR-SDRAM Has Finally Arrived http://www4.tomshardware.com/motherboard/20001030/

Introduction

The first time we heard about the future successor of the popular SDRAM memory type 'DDR'-SDRAM is several years ago now. Back then it simply sounded like the logical consequence to prolong the life of synchronous memory and the anticipation was as high as the expectation to soon welcome this speed-improved new memory type in the market. It took surprisingly long until now finally the first DDR SDRAM-equipped systems started to become available. The main reason for the long delay was the once so strong semi-monopolist Intel, which had announced about two years ago, that the future performance memory type would not be DDR-SDRAM memory, but Rambus RDRAM. At this time it almost looked as if DDR-SDRAM would never make it in the PC as main memory, because products that weren't supported by Intel's processors happened to die within a short period of time.

Intel And Rambus Weren't Able To Stop DDR-SDRAM

Things worked out differently though. The marriage with Rambus started an unfortunately long line of failures for the Santa Clara-based chipmaker. At the same time Intel's arch rival AMD started to come out with the K7-architecture, today known as Athlon and Duron, which happened to be rightfully received very positively. AMD gained market share while Intel lost it. The Taiwanese chipset maker VIA benefited from Intel's Rambus-policy as well and finally all the support was there that was needed for the Article Info successful launch of the DDR-SDRAM technology. Intel had to learn that DDR-SDRAM Has products could be successful even without the blessing from Santa Clara. Finally Arrived Today, Intel has finally announced the break-up with Rambus and we Created: know that there will be Intel-chipsets with DDR-SDRAM support soon October 30, 2000 too. By: Thomas Pabst