Slashdot Mirror
"Magnetic Tornadoes" Could Offer New Data Storage Tech
coondoggie writes to tell us about the latest technique researchers are investigating as a possible means to store data, magnetic tornadoes. "Conventional computer memories store data in "bits" that consist of two magnetic elements that record data in binary form. When these elements are magnetized in the same direction, the computer reads the bit as a '0'; when magnetized in opposite directions, the bit represents a '1,' researchers stated. According to scientists, a vortex forms spontaneously — one vortex per disk — in a small magnetic disk when the disk's diameter falls below a certain limit. Although the vortex does not whirl about like a meteorological tornado, the atoms in the material do orient themselves so that their magnetic states, or 'moments,' point either clockwise or counterclockwise around the disk's surface. At the center of the disk, the density of this rotation causes the polarity of the vortex core to point either up out of the disk or down like a tornado's funnel, researchers stated. Because the vortices that form on the disks contain two independently controllable and accessible magnetic parameters, they could form the basis for quaternary bits that would contain data written as a 0, 1, 2, or 3."
Is a "quaternary bit" a "quaternary binary digit"? Doesn't make sense. I think you're after a "quaternary digit", or "quit".
Quaternary would directly translate from binary. No fuzzy math needed.
00b=0q
01b=1q
10b=2q
11b=3q
Each quaternary bit would store two binary bits, all translated by the device. Bytes would still be 8 binary bits, but only 4 quaternary bits. Much easier than translating between trinary and binary...
And, as they are talking about storage medium, NOT processors, there's no need to recompile. Just have the device handle the translation, much in the same way it's done for CDs and flash memory.
You might want to go look up the differences between MLC and SLC Flash.
It's just bit packing. For example (and ignoring many low level details*) your 512-byte sector would be stored in 2048 hardware bit buckets instead of 4096 individual storage quanta.
* For purposes of illustration and ignoring the smart little tricks of hardware reality.
Building a better backup.
Zettabyte Storage
This sounds a lot like magnetic bubble memory that intel, fujitsu, IMB and TI made in the 1980s.
That too had multiple states per "bubble". However the higher-order bubbles were generally not used. The reason was, it was hard enough keeping the single bit (zeroth order mode) bubbles stable at high circulation and high density.
Since here the domains are fixed and the disk moves it might be easier to use higher order magnetic domain modes.
Magnetic vortices are significantly smaller than the bubbles in bubble memory. Because of this, there are no "higher order" states - you have 4 distinct magnetization states (CW/CCW, in/out), and there are no in-between states. The trick is figuring out how to get the switching speed down using exchange bias coupling and crazy anisotropy effects.
That would be four quaternary bits to make a byte, I believe.
2^8 = 256 possible values (binary; 8 places, 2 possible values each)
4^4 = 256 possible values (quaternary; 4 places, 4 possible values each)
Don't blame me -- I voted for Roslin.