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DRAM types

In electronic engineering, DDR3 SDRAM or double-data-rate three synchronous dynamic random access memory is a random access memory technology used for high speed storage of the working data of a computer or other digital electronic device. SDRAM refers to synchronous Dynamic random access memory, a term that is used to describe dynamic random access memory that has a synchronous interface SDRAM refers to synchronous Dynamic random access memory, a term that is used to describe dynamic random access memory that has a synchronous interface DDR SDRAM ( double data rate synchronous dynamic random access memory) is a class of memory Integrated circuit used in Computers It achieves nearly twice Direct Rambus DRAM or DRDRAM (sometimes just called Rambus DRAM or RDRAM) is a type of synchronous dynamic RAM, designed by the Rambus XDR DRAM or extreme data rate Dynamic random access memory is a high-performance RAM interface and successor to the Rambus RDRAM it XDR2 DRAM is a type of Dynamic Random Access Memory that is offered by Rambus. V irtual C hannel R andom A ccess M emory ( VC-RAM GDDR3, Graphics Double Data Rate 3, is a graphics card-specific memory technology designed by ATI Technologies with the collaboration of JEDEC GDDR4 SDRAM (Graphics Double Data Rate version 4 is a type of Graphics card memory specified by the JEDEC Semiconductor Memory Standard GDDR5 (Graphics Double Data Rate version 5 is a type of Graphics card memory the standards of which were set out in the GDDR5 specification by JEDEC Electronic engineering is a discipline dealing with the behavior and effects of Electrons (as in electron tubes and transistors and with electronic devices systems or equipment In Computing, a Computer bus operating with double data rate transfers data on both the rising and falling edges of the Clock signal. SDRAM refers to synchronous Dynamic random access memory, a term that is used to describe dynamic random access memory that has a synchronous interface A computer is a Machine that manipulates data according to a list of instructions. Digital electronics are Electronics systems that use Digital signals Digital electronics are representations of Boolean algebra also see

DDR3 is part of the Harder family of technologies and is one of the many DRAM (dynamic random access memory) implementations. DDR3 SDRAM is an improvement over its predecessor, DDR2 SDRAM.

The primary benefit of DDR3 is the ability to run its I/O bus at four times the speed of the memory cells it contains, thus enabling faster bus speeds and higher peak throughput than earlier memory technologies. However, greater bus speed and throughput is achieved at the cost of higher latency. SDRAM latency refers to the delays incurred when a Computer tries to access Data in SDRAM. In addition, the DDR3 standard allows for chip capacities of 512 megabits to 8 gigabits, effectively enabling a maximum memory module size of 16 gigabytes. A megabit is a unit of Information or computer storage abbreviated Mbit (or Mb) A gigabit is a unit of information or computer storage abbreviated Gbit (or Gb)

Contents

Overview

DDR3 memory promises a power consumption reduction of 30% compared to current commercial DDR2 modules due to DDR3's 1. 5 V supply voltage, compared to DDR2's 1. 8 V or DDR's 2. 5 V. The 1. 5 V supply voltage works well with the 90 nanometer fabrication technology used for most DDR3 chips. The 90 nanometer (90 nm process refers to the level of CMOS process technology that was reached in the 2002-2003 timeframe by most leading semiconductor companies Some manufacturers further propose using "dual-gate" transistors to reduce leakage of current. [1]

According to JEDEC[2] the maximum recommended voltage is 1. JEDEC Solid State Technology Association, formerly known as J oint E lectron D evice E ngineering C ouncil ( JEDEC) or Joint 575 volts and should be considered the absolute maximum when memory stability is the foremost consideration, such as in servers or other mission critical devices. In addition, JEDEC states that memory modules must withstand up to 1. 975 volts before incurring permanent damage, although they may not actually function correctly at that level.

The main benefit of DDR3 comes from the higher bandwidth made possible by DDR3's 8 bit deep prefetch buffer, in contrast to DDR2's 4 bit prefetch buffer or DDR's 2 bit buffer. The prefetch buffer is a memory cache located on modern RAM modules which stores data before it is actually needed DDR SDRAM ( double data rate synchronous dynamic random access memory) is a class of memory Integrated circuit used in Computers It achieves nearly twice

Theoretically, DDR3 modules can transfer data at the effective clock rate of 800–1600 MHz using both rising and falling edges of a 400–800 MHz I/O clock. In comparision, DDR2's current range of effective data transfer rate is 400–800 MHz using a 200–400 MHz I/O clock, and DDR's range is 200–400 MHz based on a 100–200 MHz I/O clock. To date, the graphics card market has been the driver of such bandwidth requirements, where fast data transfer between framebuffers is required. A framebuffer is a video output device that drives a video display from a memory buffer containing a complete frame of data

DDR3 prototypes were announced in early 2005. Products in the form of motherboards are appearing on the market as of mid-2007[3] based on Intel's P35 "Bearlake" chipset and memory DIMMs at speeds up to DDR3-1600 (PC3-12800). Year 2007 ( MMVII) was a Common year starting on Monday of the Gregorian calendar in the 21st century. This is a list of Computer Motherboard Chipsets made by Intel. [4] AMD's roadmap indicates their own adoption of DDR3 in 2008.

DDR3 DIMMs have 240 pins, the same number as DDR2, and are the same size, but are electrically incompatible and have a different key notch location. [5]

Latencies

The typical latency for a DDR2 JEDEC standard was 5-5-5-15. The JEDEC standard latencies for the newer DDR3 memory are 7-7-7-15. SDRAM latency refers to the delays incurred when a Computer tries to access Data in SDRAM. Another thing with the latencies to be aware of is that these are the standards. As manufacturing improves with the memory modules, the modules will be able to run at lower latencies than the JEDEC specifications. It is possible to find DDR2 memory that is faster than the 5-5-5-15 speeds right now. It will take some time for DDR3 to get below the JEDEC latencies.

GDDR3 memory, having a similar name but from an entirely dissimilar technology, has been in use for high-end graphic cards by companies such as NVIDIA and ATI Technologies. GDDR3, Graphics Double Data Rate 3, is a graphics card-specific memory technology designed by ATI Technologies with the collaboration of JEDEC The multinational NVIDIA Corporation ( (ɪnˈvɪdiə specializes in the manufacture of graphics-processor technologies for Workstations GDDR3 has sometimes been incorrectly referred to as "DDR3".

Extensions

Intel Corporation officially introduced the eXtended Memory Profile (XMP) Specification on March 23rd, 2007 to enable enthusiast performance extensions to the traditional JEDEC SPD specifications for DDR3 SDRAM. [6]

Specification standards

Chips and modules

Standard name Memory clock Cycle time I/O Bus clock Data transfers per second Module name Peak transfer rate
DDR3-800 100 MHz 10 ns 400 MHz 800 Million PC3-6400 6400 MB/s
DDR3-1066 133 MHz 7. A megabyte is a unit of Information or Computer storage equal to either 106 (1000000 Bytes or 220 (1048576 bytes depending on 5 ns 533 MHz 1066 Million PC3-8500 8533 MB/s
DDR3-1333 166 MHz 6 ns 667 MHz 1333 Million PC3-10600 10667 MB/s[1]
DDR3-1600 200 MHz 5 ns 800 MHz 1600 Million PC3-12800 12800 MB/s
Features

DDR3 SDRAM Components:

DDR3 Modules:

Advantages compared to DDR2
Disadvantages compared to DDR2

References

  1. ^ McCloskey. , Alan. Research: DDR FAQ. Retrieved on 2007-10-18. Year 2007 ( MMVII) was a Common year starting on Monday of the Gregorian calendar in the 21st century. Events 1009 - The Church of the Holy Sepulchre, a Christian church in Jerusalem, is completely destroyed by the Fatimid
  2. ^ JEDEC JESD 79-3A (section 6, tables 21 and 22)
  3. ^ Soderstrom, Thomas (2007-06-05). Year 2007 ( MMVII) was a Common year starting on Monday of the Gregorian calendar in the 21st century. Events 70 - Titus and his Roman Legions breach the middle wall of Jerusalem in the Siege of Jerusalem Pipe Dreams: Six P35-DDR3 Motherboards Compared. Tom's Hardware.
  4. ^ Fink, Wesley (2007-07-20). Year 2007 ( MMVII) was a Common year starting on Monday of the Gregorian calendar in the 21st century. Events 1304 - Wars of Scottish Independence: Fall of Stirling Castle - King Edward I of England takes the last rebel stronghold Super Talent & TEAM: DDR3-1600 Is Here!. AnandTech.
  5. ^ "DocMemory" (2007-02-21). Year 2007 ( MMVII) was a Common year starting on Monday of the Gregorian calendar in the 21st century. Events 362 - Athanasius returns to Alexandria. 1245 - Thomas, the first known Bishop of Finland Memory Module Picture 2007.
  6. ^ Coles, Olin. DDR3 RAM: System Memory Technology Explained. Retrieved on 2008-05-11. 2008 ( MMVIII) is the current year in accordance with the Gregorian calendar, a Leap year that started on Tuesday of the Common Events 330 - Byzantium is renamed ''Nova Roma'' during a dedication ceremony but is more popularly referred to as Constantinople

See also

External links

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