Synchronous DRAM

Synchronous DRAM

This article is provided by FOLDOC - Free Online Dictionary of Computing (foldoc.org)

SDRAM

(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.)
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References in periodicals archive ?
Emerging volatile next generation memory technologies included in the report are Static Random Access Memory (SRAM) and Dynamic Random Access Memory (DRAM), which include Synchronous DRAM (SDRAM), mobile DRAM, and other emerging DRAM technologies.
This is possible because the device integrates a low voltage Double Data Rate III Synchronous DRAM. Usually installed for a Notebook PC, this helps in 8 percent power saving than the regular DRAM.The Mini PC is also unnaturally stealthy in its operations and one doesn't hear the usual fan-noise that is associated with PCs.
ProMOS, the world's eighth-largest dynamic access random memory chip maker, will manufacture double data rate 3 synchronous DRAM chips, or DDR3 SDRAM chips, at a rate of 35,000 300-millimeter silicon wafers a month under the Elpida brand, it said.
The Model T5372 Memory Tester reduces wafer test time for dynamic random-access memory (DRAM), synchronous DRAM (SDRAM), double-data-rate (DDR)-SDRAM, flash-memory, and other general-purpose memory chips as well as for multichip packages and other specially packaged memories.
The latest investment is aimed at helping Elpida accelerate production of DDR2 SDRAM (double-date rate synchronous DRAM) chips for use with a new Intel microprocessor targeted at high-performance PCs and servers.
Micron Technology, Inc., has demonstrated the industry's first 1Gigabit (Gb) Double Data Rate (DDR) synchronous DRAM (SDRAM) components manufactured on 0.11 micron process technology.
In addition, the impending industry change from standard synchronous DRAM chips to faster double data rate (DDR) chips may have led some manufacturers to launch a ``fire sale'' of old product in October.
Samsung Electronics has developed a 64Mb double-data-rate synchronous DRAM device that operates at up to 300MHz.
Infineon Technologies (DAX/NYSE: IFX) has reinforced its leading position in high-performance memory technologies by introducing the fastest version of its 128-Mbit synchronous DRAM (SDRAM), and the related unbuffered modules.
This is possible to do using today's very fast SRAM or synchronous DRAM memory.
The LT has a 4.3GB hard drive that is shock-mounted, along with 64MB of synchronous DRAM.

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