January JEDEC. STANDARD. DDR2 SDRAM SPECIFICATION be addressed to JEDEC Solid State Technology Association, Wilson Boulevard. DDR2 SDRAM is a double data rate synchronous dynamic random-access memory interface. It superseded the original DDR SDRAM specification, and is superseded by .. JEDEC standard: DDR2 SDRAM Specification: JESDF, November ** ยท JEDEC. The JEDEC memory standards are the specifications for semiconductor memory circuits and Memory modules of the DDR2-SDRAM type are available for laptop, desktop, and server computers in a wide selection of capacities and access.

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This page was last edited on 2 Augustat However, further confusion has specificcation added to the mix with the appearance of budget and mid-range graphics cards which claim to use “GDDR2”.

JEDEC memory standards – Wikipedia

The purpose of the standard is to promote the uniform use of symbols, abbreviations, terms, and definitions throughout the semiconductor industry. Views Read Edit View history. The specification contains definitions of the commonly used prefixes kilomegaand giga usually combined with the units byte and bit to designate multiples of the units. Dynamic random-access memory DRAM.

The lower memory clock frequency may also enable power reductions in applications that do not require the highest available data rates. These cards actually use standard DDR2 chips designed for use as main system memory although operating with higher latencies to achieve higher clockrates.

The specification notes that these prefixes are included in the document only to reflect common usage.



This article needs to be updated. Such chips draw significantly more power than slower-clocked chips, but usually offered little or no improvement in real-world performance.

By using this site, you agree to the Terms of Use and Privacy Policy. DIMMs are identified by their peak transfer capacity often called bandwidth. JEDEC standards and publications are designed to serve the public interest through eliminating misunderstandings between ddr22 and purchasers, facilitating interchangeability and improvement of products, and assisting the purchaser in selecting and obtaining with minimum delay the proper product for use by those other than JEDEC members, whether the standard is to be used either domestically or internationally.

The specification defines the two common units of information: Both performed worse than the original DDR specification due to higher latency, which made total access times longer.

The standards specify the physical and electrical characteristics of the modules, and include the data for computer simulations of the memory module operating in a system. specificcation

Please update this article to reflect recent events or newly available information. Bandwidth is calculated by taking transfers per second and multiplying by eight.

The standards specify memory module label formats for end-user markets. This committee consists of members from manufacturers of microprocessors, memory ICs, memory modules, and other components, as well as component integrators, such as video card and personal computer makers. Views Read Edit View history.

JEDEC memory standards

DDR2 was introduced in the second quarter of at two initial clock rates: Retrieved August 25, From Wikipedia, the free specificatlon. An alternative system is found in Amendment 2 to IEC The definitions of kilo, giga, and mega based on powers of two are included only to reflect common usage. During an access, four bits were read or written to jwdec from a four-bit-deep prefetch queue.


The documentation of modern memory modules, such as the standards for the memory ICs [4] and a reference design of the module [5] requires over one hundred pages. From Wikipedia, the free encyclopedia.

JEDEC JESD79 | DDR SDRAM Specification | Electronics Notes

This queue received or transmitted its data over the data bus in two data bus clock cycles each clock cycle transferred two bits of data. Wikipedia articles in need of updating from January All Wikipedia articles in need of updating. This page was last edited on 11 Januaryat The document notes that these prefixes are used in their decimal sense for serial communication data rates measured in bits.

The document further refers to the description of the IEC binary prefixes in Amendment 2 of IEC”Letter symbols to be used in electrical technology”for an alternate system of prefixes [notes 1] and includes a table of the IEC prefixes jesec the note.

At least one manufacturer has reported this reflects successful testing at a higher-than-standard data rate [4] whilst others simply round up for the name. Archived from the original on This packaging change was necessary to maintain signal integrity at higher bus speeds.