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Fast-Switching Micromagnets
apirkle writes "Why can't we use magnetic media as RAM? Flipping the north and south poles of the tiny magnets we call bits simply takes too long. A collaboration of researchers has recently demonstrated a much faster method for reversing magnetization, described in Physical Review Focus."
Actually, tiny ferrite cores used to be used as magnetic memory. It wasn't called "RAM" then, but "core"... it was pretty cool stuff, (mostly) nonvolatile if a system powered off, but when you read a bit you had to rewrite it. It was invented in the 50's I think, and the inventor licensed it to many computer companies and made a healthy profit.
;)
It seems those old sci-fi stories predicting computers of the future to have microscopic core memory (but still core memory) may very well come true
--TheOrangeSquid Is it any wonder things seem so awry? We swim in a sea of confusion and don't have to think to survive
The simpsons did it ....
No really, IBM has been working on this stuff for a couple years now, the projected release date is 2004.
Here and Here
it was cool. it worked like this a slab of magnetic material could have small (circular) islands of magnetism. from above this looks like a sea of dots on a surface.
Now onto the surface one writes a set of T shapped (or chevron shapped) pieces of permaloy. thousands of these in rows. The manetic bubbles are attracted to the edges of these T's and stick to them. When a transverse magnetic field is applied the T's become bar magnets and the bubbles move to one end to the bar margnet. rotate the magnetic filed the the bubbles move from one side of the T to the other. If the magnetic field is strong enough they will Jump from one T to the text. seen from above the magnetic bubbles march in lock step from one T to the next each rotation of the magnetic field.
ones and zeros are encoded either as presensce or absence of bubbles in the series of marching bubbles, or better yet by using higher order magnetization patterns within each bubble (N-bits per bubble).
since the materials are transparent and the bubbles are optically active, you can read out the bubbles with light. These things were built as large bucket brigades, just as CCD chips often are. You dont try to address a location on the chip directly. instead to determine the value of a bit, you shffle the whole marching line along until that bit position reaches your detector and you read it out. Thus its a serial access device (with many read heads). It's all solid state. the media is fixed (does not spin), instead the bits in the media move!!!
the problem was that these things were slower than Ram, and faster than hard drives. they were denser then ram but not as fast as harddrives. thus they had a niche rolle as non-volatile hard drive caches. their role as non-volatile memeory got squezed out by flash memory on the low end and harddrives on the high end.
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