EDO Random Access Memory

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Extended Data Out (EDO) DRAM is a now-obsolete type of RAM that could keep an area of memory “open,” allowing faster reads or writes when all of the memory accessed was clustered together in a group. It also allowed the previously read data to remain available when a new memory location was read from or written to. This allowed a bit of pipelining of memory access, improving performance further.

EDO DRAM was introduced in the early 1990’s, and began to replace the previous DRAM technology (Fast Page Mode or FPM DRAM) by the mid 1990’s. In addition to finding common use in personal computers as main memory, EDO RAM was also used as cache memory on some systems and as video RAM on some graphics cards (although generally, the term “Video RAM” usually implies a dual-ported access scheme, which didn’t exist in EDO).

EDO was sold in Single In-Line Memory Modules (as opposed to Dual In-Line Memory Modules), which meant that most systems required them to be installed in pairs.

If you’re looking for EDO Ram to update an older computer, prices on the Internet can range from 7 to 17 cents per megabyte.



Sources:
http://ftp.columbia.edu/acis/history/core.html
http://en.wikipedia.org/wiki/DDR_SDRAM
http://en.wikipedia.org/wiki/DIMM
http://www.oempcworld.com/support/Install_168pin_DIMM.htm
http://en.wikipedia.org/wiki/Delay_line_memory
http://en.wikipedia.org/wiki/Core_memory

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