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MRAM Last modified: Thursday, June 12, 2003

Short for magnetoresistive RAM, or magnetic RAM, a non-volatile RAM memory technology that uses magnetic charges to store data instead of electric charges, such as those used in SRAM and DRAM technologies. Unlike a technology such as DRAM, which requires a constant flow of electricity to maintain the integrity of the data, MRAM will retain data even when the power is turned off and only requires a small amount of electricity to store data bits. For example, in a PC enabled with MRAM, the computer would start up instantly instead of having to wait for the BIOS to locate and load the computer’s operating system software. Technically, MRAM works by placing millions of magnetic “sandwiches” on a silicon substrate, with tiny parallel wires running in one direction on top of them and more perpendicular wires running below, creating a woven effect in the wiring. A single bit is represented at each point where the top and bottom wires cross. To write a bit onto the chip, a current passes through a wire on top of the sandwich and flips the polarity on one of the magnets. To read a bit from a chip, a current travels through the structure and measures the resistance of each magnet. Low resistance equals “0” and high resistance equals “1.” The sandwiches remain in their magnetic states until the data is rewritten or erased by the system. MRAM, first developed by IBM in the 1970s, is expected to replace DRAM as the memory standard in electronics.

Instant Access Memory This 2000 article from Wired magazine looks at the birth of MRAM and its implications for the future of computing.