27 Ekim 2007 Cumartesi

Magnetoresistive Random Access Memory

Magnetoresistive RAM Wikipedia

Freescale MRAM

Magnetoresistive Random Access Memory (MRAM) is a non-volatile computer memory (NVRAM) technology, which has been under development since the 1990s. Continued increases in density of existing memory technologies, notably Flash RAM and DRAM kept MRAM in a niche role in the market, but its proponents believe that the advantages are so overwhelming that MRAM will eventually become dominant.

Unlike conventional RAM chip technologies, in MRAM data is not stored as electric charge or current flows, but by magnetic storage elements. The elements are formed from two ferromagnetic plates, each of which can hold a magnetic field, separated by a thin insulating layer. One of the two plates is a permanent magnet set to a particular polarity, the other's field will change to match that of an external field. A memory device is built from a grid of such "cells".

MRAM has similar speeds to SRAM, similar density of DRAM but much lower power consumption than DRAM, and is much faster and suffers no degradation over time in comparison to Flash memory. It is this combination of features that some suggest make it the "universal memory", able to replace SRAM, DRAM and EEPROM and Flash. This also explains the huge amount of research being carried out into developing it.

Early History

* 1955 - Magnetic core memory had the same reading writing principle as MRAM
* 1988 - IBM scientists made a string of key discoveries about the "giant magnetoresistive effect" in thin-film structures.
* 2000 - IBM and Infineon established a joint MRAM development program.
* 2002 - NVE Announces Technology Exchange with Cypress Semiconductor.
* 2003 - A 128 kbit MRAM chip was introduced, manufactured with a 180 nm lithographic process

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