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Magnetic Microchips
Mr_Ceebs writes, "Looking at the BBC today I find a new Magnetic rather than electronic chip type. The design can raise the number of chips per cm by a factor of about 1000, with the preliminary stages of the technology. For all devices this would mean the demise of the large battery pack. " H : This is a follow-on to this morning's story on moldable magnets.
This is SO cool! With this stuff you can turn your computer off, turn it back on and be right where you left off!
Even better, when you're not using your computer, you can stick it to the 'fridge.
George
The days of carrying around heavy batteries for laptop computers and mobile phone are numbered
This is not entirely true, for mobile phones at least. The bulk of the power consumption is from the antenna. Your standby time could be increased greatly, but talk time will likely be uneffected. Thus, in order to talk for a reasonable length of time, batteries will probably stay the same size.
-ShelbyCobra
Living life in the right side of the s-plane
Nice to see what goes around, comes around. Core memory in a dip package. Magnetic bubble memory was a first attempt at this but it took too long to move the bubbles around the ramps. This looks more feasable and the heat dissipation problem is gone. Is there any real reason to have mobile mass storage when you can have high density static memory? If you remove the heat problem, there's no real limitation to using three dimensions for the layout. Just build the chip up in layers.
Controllers for space/time capsules (see Doctor Who: Wargames)
Linux port for iron filings
Compass that doubles as a Quake 3 client
Levitating trains (aka: Bullet train) with SETI@Home and distributed.net clients
Finally, for the more serious-minded, I'll be interested to know if this is specific to ferro-magnetic objects. Superconductors are also magnetic, but in a completely different way.
It's a small world and it smells funny; I'd buy another if it wasn't for the money; Take back what I paid (SoM)
There are sense wires that detect a field in the "spot" so you can read the memory field direction to specify a 1 or a zero. Just like the old magnetic donuts used in core memory without the hundreds of Tiwainese ladies stringing the beads (they had the smallest fingers to be able to do it in the 60s)
That's old hat these days. The latest joy in systems research is nanokernels for OPJS.
Charming
take a triptonica to subthunk
Check out Scientific American (from last year). This stuff looks more and more interesting everyday.
For those of you who don't know what core memory is or how it works:
Core memory consisted of a number of ferrite cores strung at the intersections of wires arranged in a grid. The cores were like, little rings of material with magnetic properties.
To set a core to a 1 or a zero, half of the current needed would be sent down the "X" wire, and half would be sent down the "Y" wire - where the wires crossed (and where the core was), the magnetic polarity of the core would be set, because the full current necessary to set the polarity would then be present at the junction. If the polarity needed to be reversed, the voltage would be inverted on the wires to perform this. The polarity of the core determined whether the bit (which a core represented - 1 bit of information) was a 1 or a 0 in value.
Reading a core worked similar to writing the core, except in this case, a third wire was used. This wire was weaved through the cores in a diagonal fashion, started at one corner, and worked back ad forth through the cores to the opposite corner. The reason the wire was put on a diagonal, was to minimize the signal picked up - if it was on the same path as the X or Y wires, you couldn't use this wire to pick up the signal, because the signal would be that of the current used to flip the polarity...
Anyhow, this wire was called the "sense" wire. To see what a core's value was, the core was written to. If there existed a value in the core (the core was saturated and magnetized to some polarity), and the polarity of the written value was the same, nothing would appear on the sense wire, and so the data had the same value as what was being written. If the polarity of the written value was different, then the act of setting the value would cause a change in voltage to be picked up in the sense wire, in effect signaling that the value was opposite that of what was being written. Here is where a problem came in...
When reading a value, the value in the core is written to, and the writing to that core could cause the core to change value! This reading process was hence known as a destructive read, since the data could be changed. So, after a read, the data had to be re-written to the same core, so that it wouldn't change.
A fourth wire is also found in core memory - I can't remember what this wire wass called or what it was used for (was it a "gate" wire?) - I think it came later in core memory development, when they started making extremely tiny core systems (some of which can still be found on Ebay - man, these things are small).
BTW - I am not old enough either to "remember" core memory - I just have read enough about it, and have some really old computer textbooks and history books that explain all the concepts really well. I have been thinking about building my own small core memory system, accessing it through the parallel port or an ISA slot. I bought a whole mess of small 3-5 millimeter ferrite cores. Not small like the advanced systems were, but they don't need to be - since I will be hand threading these...
Reason is the Path to God - Anon
okay, i'm figuring that i'm the only one posting that actually has experience in fabricating and measuring magnetic nanostructures so here goes:
the BBC article is typically crap. what happens is someone from cambridge or oxford needs PR so they call up the press and tell them how many transistors they can squeeze onto the head of a pin. in the end, there's really no science in the article and, for those astute readers out there, in this particular article they don't make much mention of how these things work, what material they are using, what temperature they've demonstrated these things at, etc.
Typically, these estimates on transistor density are made when the lab produces a prototype with the active elements within a certain area. by no means does this mean that they've constructed a 5.5 billion density device that works.
they don't tell you what the mechanism is-- tunneling magnetoresistance (TMR) or spin-diffusion/accumulation ('Johnson spin transistors'), however the switching speeds are estimated to be much faster than conventional semiconductor devices (there's some argument for this in IEEE spectrum from about 5 yrs back that i can't remember).
reliability?
they have omitted mention of the gate mechanism here. how do they plan on switching these things individually? telepathy? if they are using EM fields generated by wires, then there is the inevitable heating to deal with. what material are they using? what's the curie temperature? how hot do they expect these things to get? hey wait! there's no size bar on that pretty picture of the magnets!?
blah blah blah.
BAD JOURNALISM from the BBC.
i may be a jerk about this, but i think everyone's getting a bit caught up in the hype without enough data and it's irritating as a scientist.
Sure, why not.
With bipolar transistor, a small amount of base current controls a larger amount or collector current. If you operate it in the linear region, you've made an amplifier. If you saturate it, you've made a switch. It's a current controlled current source.
An FET is a voltage controlled current source. A small change in gate to source voltage brings about a relatively large change in drain current. FETs can also be operated in a linear or "constant current" region. So you can make amplifiers or switches from them too.
Vacuum Tubes work similarly to FETs except that a "1" is damned big, say 100-400 Vdc! Instead of the gate and source you have a grid and cathode; instead of the drain, tubes have a plate.
... which brings me to magnetic amplifiers. The germans used these in the electrical controls of their U boats. They were totally sealed because they had no parts which would fail. They were extremely rugged, never going into microphonics like tubes would when some destroyers started pounding the sub with depth charges. Magnetic Amplifiers are made with toroidal square loop cores. A small current through a control winding established the volt-seconds of reset to the core. By varying this, much larger electrical signals can be regulated. If different core materials are substituted, it is possible to store the state of the core flux. Then you have core memory.
What these englishmen have figured out is how to microminiturize core memory without having to wind cores, etc.. Schweet!
Wansu, th' chinese sailor