(redirected from DDR266)


McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.


This article is provided by FOLDOC - Free Online Dictionary of Computing (


(Synchronous DRAM) The type of dynamic RAM memory chip in wide use since the mid-1990s. SDRAM divides the chip into two cell blocks and interleaves data between them. While a bit in one block is accessed, a bit in the other is prepared for access. See dynamic RAM.

DDR (Double Data Rate) Since 2000
DDR SDRAM doubled the data transfer rate by using both the rising and falling edges of the clock cycle, and more speed is achieved with each generation (see below).

Memory Channels
Motherboards may support one, two or four channels. More than one channel requires installing modules in a prescribed order (see image below). See GDDR.

        Clock    Transfer        DIMM        Speed      Rate         Module DDR    (MHz)     (MT/s)    (V)  Pins

 DDR5 1600-3200  3200-6400  1.1  288
 DDR4  800-1600  1600-3200  1.2  284
 DDR3  400-1200   800-2400  1.5  240
 DDR2  200-533    533-800   1.8  240
 DDR   100-200    200-400   2.5  184
 SDRAM  66-133     66-133   3.3  168

Matched Slots for Dual Channel
Dual-channel motherboards use color-coded sockets so that DDR memory modules are inserted in pairs. This motherboard supports two pairs of DIMM modules (see memory module).

DDR RAM Modules Are "Keyed"
This example shows the notching of three DDR generations. Modules and slots are "keyed" to prevent the wrong DDR version from being inserted. See memory module.

A Little Nostalgia
These 12 bits of magnetic core memory from the Whirlwind computer of the early 1950s take up about a quarter of a square inch. Today, that much space holds billions of bits. (Image courtesy of The MITRE Corporation Archives.)
Copyright © 1981-2019 by The Computer Language Company Inc. All Rights reserved. THIS DEFINITION IS FOR PERSONAL USE ONLY. All other reproduction is strictly prohibited without permission from the publisher.
References in periodicals archive ?
The BCM3381 is the industry's leading single-chip DOCSIS/EuroDOCSIS channel bonding cable modem solution that combines radio frequency (RF) receivers in support of both advanced QAM and S-CDMA, an advanced QAM transmitter, a complete DOCSIS 2.0+ media access controller (MAC) with channel bonding capabilities, an 800-DMIPS communications processor, a DDR266 DRAM interface, Ethernet and USB interfaces, and expansion capabilities to support VoIP and wireless connectivity.
Dataram's 8GB DRHZX2000/8192, for the zx2000 workstation, and DRHZX6000/8192, for the zx6000 workstation, contain two registered ECC DDR266 DIMMs built with advanced, high-density one-gigabit DRAMs.
The 120Rd-1 and 120Rf-2 feature I/O capabilities, a 533MHz Front Side Bus, 12GB of DDR266 SDRAM and embedded, Ultra 320 SCSI and Gigabit Ethernet controllers, an Intel E7501 chipset and up to two Intel Xeon processors running at speeds of up to 2.8GHz.
The new notebook incorporates a 15-inch XGA display and comes standard with 256MB DDR266 onboard system memory upgradeable to 512MB, a nine-cell Lithium ion battery and two Type II or one Type III PC card slots.
CyberALADDiN-T is the world's first low-power integrated graphics & core logic solution supporting both Double-Data- Rate memory technology (DDR266) and Intel's latest Pentium III processor-M for mobile applications.
For HPC applications that utilize very intensive read/write cycles in a high reliability environment, low latency 2-2-2 DDR266 DIMMs can help system memory performance.
The 845PE chipset offers DDR333 memory and AGP4x support and the Intel 845GV features DDR266 main memory capability and a 533MHz or 400MHz system bus.
Dataram's 512MB and 1GB upgrade (DRL650/512 and DRL650/1024 respectively) consists of a single ECC DDR266 DIMM that is 100% compatible with the Dell Precision 450 and 650 workstations and is backed by Dataram's lifetime warranty and free technical support.
As the newest addition to Samsung's DDR SDRAM portfolio, the 400Mbps (200MHz) DDR devices are ideal for use as PC system main memory, offering three times the performance of Single-Data-Rate PC 133 SDRAM and 50 percent more bandwidth than mainstream DDR266.