Editing DDR SDRAM (section)

=== Chip characteristics ===
[[File:SAMSUNG@DDR-SDRAM@64MBit@K4D62323HA-QC60 Stack-DSC03539-DSC03556 - ZS-DMap.jpg|thumb|The [[die (integrated circuit)|die]] of a Samsung DDR-SDRAM 64MBit package]]
;DRAM density: Size of the chip is measured in [[megabits]]. Most motherboards recognize only 1&nbsp;GB modules if they contain ''64M×8'' chips (''low density''). If ''128M×4'' (''high density'') 1&nbsp;GB modules are used, they most likely will not work. The [[JEDEC]] standard allows ''128M×4'' only for registered modules designed specifically for servers, but some generic manufacturers do not comply.<ref>{{cite web|url=http://reviews.ebay.com/Myth-Low-Density-vs-High-Density-memory-modules_W0QQugidZ10000000001236178|title=Low Density vs High Density memory modules|website=eBay|access-date=2009-01-21|archive-date=2012-03-03|archive-url=https://web.archive.org/web/20120303072655/http://reviews.ebay.com/Myth-Low-Density-vs-High-Density-memory-modules_W0QQugidZ10000000001236178|url-status=dead}}</ref><ref>{{cite web |title=Vostro 230, 4GB max incorrect, explanation |url=https://www.dell.com/community/en/conversations/vostro-desktops/vostro-230-4gb-max-incorrect-explanation/647f8052f4ccf8a8deefdb84 |website=DELL Technologies |language=en |date=10 April 2019}}</ref>
;Organization: The notation like ''64M×4'' means that the memory matrix has 64 million (the product of ''banks'' x ''rows'' x ''columns'') 4-bit storage locations. There are ''×4, ×8,'' and ''×16'' DDR chips. The ''×4'' chips allow the use of advanced error correction features like [[Chipkill]], [[memory scrubbing]] and Intel SDDC in server environments, while the ''×8'' and ''×16'' chips are somewhat less expensive. ''x8'' chips are mainly used in desktops/notebooks but are making an entry into the server market. There are normally 4 banks and only one row can be active in each bank.

==== Double data rate (DDR) SDRAM specification ====
From Ballot JCB-99-70, and modified by numerous other Board Ballots, formulated under the cognizance of Committee JC-42.3 on DRAM Parametrics.

Standard No. 79 Revision Log:
*Release 1, June 2000
*Release 2, May 2002
*Release C, March 2003 – JEDEC Standard No. 79C.<ref>http://www.jedec.org/download/search/JESD79F.pdf DOUBLE DATA RATE (DDR) SDRAM SPECIFICATION (Release F)</ref>

"This comprehensive standard defines all required aspects of 64Mb through 1Gb DDR SDRAMs with X4/X8/X16 data interfaces, including features, functionality, ac and dc parametrics, packages and pin assignments. This scope will subsequently be expanded to formally apply to x32 devices, and higher density devices as well."