Mechanical logic gate: Could levers replace transistors?

Sep 17, 2010 by Miranda Marquit weblog
SEM image of a released SiC NEMS switch with 3 μm length. Image credit: Science, DOI:10.1126/science.1192511

(PhysOrg.com) -- Back in the Victorian period, Charles Babbage created a mechanical computer that made use of levers and cogs to get data moving. These days, though, our computers are mostly run using electronic transistors. Nothing too mechanical about those. Unfortunately, when putting together a logic gate for use in computing, the materials used can't withstand some of the heat. Silicon carbide has been used to help fortify regular silicon, which degrades at 250 to 300 degrees Celsius. However, silicon carbide transistors are bulky and slow -- and require high voltages.

In order to get around this problem Te-Hao Lee and a team at Case Western Reserve University turned back to Babbage and his idea of mechanical computing. New Scientist reports on the effort to integrate mechanical computing into our modern electronic systems:

His team has developed a mechanical version of an inverter - the building block used to construct many types of logic gate, which themselves are a fundamental component of digital circuitry within computers. The device uses an arrangement of nanoscale levers instead of . Like a telegraph operator's Morse key, these levers physically make and break contact to pass or block currents.

Application of a voltage makes the levers move under . At 550 °C Lee's team managed to get the inverter to switch on and off 500,000 times a second - performing a computation with each cycle.

Such operating temperatures are encouraging. However, there are problems. The mechanical components start to break down after two billion cycles, limiting their usefulness. Additionally, this set up is still slower than the speeds even a normal PC sees. However, the main uses for a mechanical logic gate likely wouldn't be in consumer computing. Instead, such a device would make more sense in situations of very high heat, such as for rocket engines.

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More information: Te-Hao Lee, Swarup Bhunia, Mehran Mehregany, "Electromechanical Computing at 500°C with Silicon Carbide," Science (September 2010). Available online: www.sciencemag.org/cgi/content… stract/329/5997/1316
Paul Marks, "Steampunk chip takes the heat," New Scientist (September 10, 2010). Available online: www.newscientist.com/article/d… -takes-the-heat.html
Hamish Johnston, Logic circuit takes the heat," Physicsworld (September 14, 2010). Available online: physicsworld.com/cws/article/news/43734.

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User comments : 16

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Tuppu
2.1 / 5 (7) Sep 17, 2010
0.5 Mhz and 2 µm computer architecture with 1 hour life time is a hi-tech?
Tuppu
1.8 / 5 (5) Sep 17, 2010
.5 Mhz and 0.003 mm computer architecture with a 1 hour life time is a HI-tech?
AceLepage
5 / 5 (3) Sep 17, 2010
In an environment where conventional electronics cannot function, and where it is a one time use, this fits the bill.
SincerelyTwo
1 / 5 (6) Sep 17, 2010
Intel is now replacing internal PC wiring with optical connections and these guys want to switch to mechanical logic gates? Lol, comedy.
that_guy
1 / 5 (1) Sep 17, 2010
advancing technology all depends on the application. A rocket launch only takes a few minutes, but having a mechanical computer on scene rather than an electronic one that has to run data down the line can make faster actions for simpler decisions.
trekgeek1
not rated yet Sep 17, 2010
advancing technology all depends on the application. A rocket launch only takes a few minutes, but having a mechanical computer on scene rather than an electronic one that has to run data down the line can make faster actions for simpler decisions.


I don't think so. It's just a mechanical logic gate. The information that it operates on has got to come from somewhere. Whether mechanical or electrical, the data would be coming from the same place, either on or off chip. I'm not a computer engineer, but I'd bet that graphene will end up making this a moot point.
laserdaveb
5 / 5 (4) Sep 17, 2010
Laugh if you must but we got to the moon with 4000 "or" gates..not everything needs a P4!...500 degrees C...Rocket motors aren't the only place that it would be useful...now build all four boolean gates...
Twix
5 / 5 (4) Sep 17, 2010
0.5 Mhz and 2 mkm computer architecture with 1 hour life time is a hi-tech?
For example inside of active zone of nuclear rector - yes.
Nik_2213
not rated yet Sep 18, 2010
Furnace controllers and other industrial-strength hot-zone applications spring to mind...

FWIW, it may get into record book as fastest Morse keyer...
delemming
3.7 / 5 (3) Sep 18, 2010

I don't think so. It's just a mechanical logic gate. The information that it operates on has got to come from somewhere. Whether mechanical or electrical, the data would be coming from the same place, either on or off chip. I'm not a computer engineer, but I'd bet that graphene will end up making this a moot point.


The latest cpu is also just a collection of simple logic gates, be it very many. There is no reason for a mechanical gate to not be used to build a simple cpu+memory thing capable of operating things in an environment normal electronics cant function.
TabulaMentis
1 / 5 (1) Sep 18, 2010
Nature consist of both mechanical and photon logic?
I think Babbage's machine operated on steam?
bottomlesssoul
not rated yet Sep 19, 2010
@Tuppu
0.5 Mhz and 2 �m computer architecture with 1 hour life time is a hi-tech?
It is when it has to operate inside a rocket engine for the 10 minutes or so of operation or say as a backup for a nuclear power station during criticality excursions.
bottomlesssoul
not rated yet Sep 19, 2010
@Tuppu
0.5 Mhz and 2 �m computer architecture with 1 hour life time is a hi-tech?
It is when it has to operate inside a rocket engine for the 10 minutes or so of operation or say as a backup for a nuclear power station during criticality excursions.
A_Paradox
not rated yet Sep 20, 2010
I tend to think that a rocket engine would produce too much vibration for these things.
Parsec
not rated yet Sep 20, 2010
.5 Mhz and 0.003 mm computer architecture with a 1 hour life time is a HI-tech?


As other commenter's mentioned, it depends on the application. In addition, thinking back to the first cat whisker transistors, and the 4000 transistor chips housing the very first computers, I suspect that speed and density will obey Moore's law for a long time. The first IBM PC had a cycle time of only 8 times faster (4.4mhz).

Furthermore, the lifetime of a silicon chip in these operating conditions is like a butterfly in a blowtorch.
randomwraith
not rated yet Sep 20, 2010
There's nothing new about mechanical boolean logic gates as these people have demonstrated, albeit on a slightly larger scale ...

http://www.goldfi...gic.html
http://knexcomput...pot.com/

One suspects that mechanical molecular gates will provide more success in the long run, but it's nice to see mechanical logic in main stream research.