The document discusses the potential for carbon nanotube computers to replace silicon-based VLSI technology. It describes how carbon nanotubes have exceptional electrical and thermal properties and could be used to build transistors that do not suffer from energy leakage. The document outlines a prototype carbon nanotube computer that runs on a single instruction called SUBNEG and operates at much higher clock speeds with significantly lower energy usage than silicon processors. It envisions future improvements including more powerful instruction sets, denser memory, and the potential for carbon nanotubes to help extend Moore's Law. However, challenges remain in producing high purity metallic and semiconductor carbon nanotubes at scale.

1. Carbon Nanotube Computer
Sparsa Roychowdhury
sparsa.roychowdhury@gmail.com
November 11, 2013
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2. Outline
1
What is Carbon Nanotubes?
Types of Carbon Nanotubes
Carbon Nanotubes: Alternative to silicon based VLSI?
2
End of VLSI era?
3
Carbon Nanotubes comes to resque!
New Implementation of computer technology
Architecture
4
Architecture at Work
Parts of One instruction
5
Future
References
References
6
7
Thank You!
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3. What is Carbon Nanotubes?
What is Carbon Nanotubes?
Carbon Nanotubes?
Carbon Nanotubes are hollow, cylindrical nanostructures
composed of single sheet of carbon atoms.
Carbon Nanotubes(CNT) have exceptional electrical, physical
and thermal properties.
Carbon Nanotubes are stronger than steel and 200 times lighter
than steel.
Carbon Nanotubes are 10,000 times thinner than human hair.
Within this Single Walled Nanotube is our special interest in
building Carbon Nanotube Computers.
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4. What is Carbon Nanotubes?
Types of Carbon Nanotubes
Carbon Nanotubes can be categorized by their structures:
1
Single Wall Nano Tubes (SWNT): The structure of a SWNT
can be visualized as a layer of graphite, a single atom thick,
called graphene, which is rolled into a seamless cylinder.
2
Multi Wall Nano Tubes (MWNT): Multi-wall nanotubes can
appear either in the form of a coaxial assembly of SWNT similar
to a coaxial cable, or as a single sheet of graphite rolled into the
shape of a scroll.
3
Double Wall Nano Tubes (DWNT): Double-wall nanotubes
(DWNT) are an important sub-segment of MWNT with two
walls of carbon atoms.
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5. What is Carbon Nanotubes?
Carbon Nanotubes: Alternative to Silicon based VLSI?
Metal or Semiconductor?
1
Carbon Nanotubes can exibit both metal and semiconducor
properties.
2
The diameter and Helicity of a defect free Single Walled
Nanotubes represent the property of the nanotube, which can
also be uniquly identified by the vector,
Ch = na1 + ma2 ≡ (n, m)
3
Carbon Nanotube Field Effect Transistors are promising
candidate as an alternative of Si CMOS due to it’s excellent
perfomance.
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6. End of VLSI era?
End of VLSI Technology
End of VLSI Technology
1
Huge amount of energy leakage
2
22nm technology is achieved
3
Quantum Effects comes into action below this limit
4
cant make transistors smaller than this
5
Processor speed is limited upto 4GHz per core
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7. Carbon Nanotubes comes to resque!
New Implementation of computer technology
Carbon Nanotube Computer
1
A group of scientists of Stanford University have created world’s
first carbon nanotube processor.
2
The processor is basically free from energy leakage.
3
Highly energy efficient.
4
Can create 10-15 GHz processor in a single core.
5
Can be implemented in present computer architecures like MIPS.
“The Carbon Nanotube computer runs an operating
system that is capable of multitasking”
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8. Carbon Nanotubes comes to resque!
How the architecture works? I
How the architecture works:
The basic implementation of this computer is on
one instruction set computer. The only instruction used in this computer is SUBNEG (SUbstract
Branch if NEGetive) which is turing complete instruction in nature.
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9. Carbon Nanotubes comes to resque!
How the architecture works? II
Flow Chart of SUBNEG
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10. Carbon Nanotubes comes to resque!
Basic Architecture of Carbon Nanotube
Computer
Architecture:
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11. Architecture at Work
Stages of the Architecture
Definition
The basic operation of the architecture can be
divided in 4 stages
1
Instruction fetch: this stage supplies instruction memory with the
address to read
2
Date fetch: This stage supplies the basic data needed for the
instruction (Two operands of the SUBNEG instruction)
3
Arithmatic Operations: This stage does the necessary arithmatic
operations(Substraction in this case) for the instruction
4
Write Back: This stage write backs the output of the arithmatic
operation to the second arguement location
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12. Future
Future of Carbon Nanotube Computer
Future
1
Continuous imporovement of computational power at low energy
losses
2
This basic instruction set can be extended to more powerful
processor
3
Low metal usage helps us to built environment friendly processor
4
Memory chips with Carbon Nanotubes which gives much more
dense memory
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13. Future
Cons of Carbon Nanotube computer
Cons of CNT Computers
1
Prepartion of Carbon Nanotube are still very expensive
2
Metalic and semiconductor nanotubes cant be prepared with
high purity
3
It is very complex to build a processor using fully carbon
nanotubes
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14. References
References I
Carbon nanotubes. (n.d.). Retrieved from
http://www.nanocyl.com/en/CNT-Expertise-Centre/
Carbon-Nanotubes
First carbon nanotube computer to help extend moores law.
(2013). Retrieved from http://news.cnet.com/
8301-17938_105-57604663-1/first-carbon-nanotube
-computer-to-help-extend-moores-law/
Odom, T. W., Huang, J.-L., Kim, P., & Lieber, C. M. (1998).
Atomic structure and electronic properties of single-walled
carbon nanotubes. Nature, 391(6662), 62–64.
Shulaker, M. M., Hills, G., Patil, N., Wei, H., Chen, H.-Y., Wong,
H.-S. P., & Mitra, S. (2013). Carbon nanotube computer.
Nature, 501(7468), 526–530.
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15. Thank You!
Thank You!
Thank You!
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