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Moore
’s
Law states that
“The
Number of Transistors Per Chip Doubles Every 18 Months”
Intel
hopes to continue on the
Moore's Law curve for
about another 20 years, at which point they'll hit the theoretical physical
limitations of wafer fabrication technology.Researchers
have projected that once the smallest features of a transistor's design shrink
to less than 100 nanometers, the devices
will no longer function usefully. At that point, small-scale quantum mechanical
effects, such as tunneling of electrons through barriers (basically electrons
walking through walls), will begin to dominate the essential effects that allow
a standard semiconductor device to operate. Present-day microelectronic device
design will need to be replaced with new designs that take advantage of these
dominating effects.It
is hoped that nanometer-scale replacements to today's devices will allow the
miniaturization of computational and information storage elements to the
molecular level, with expectations for vast increases in memory density, power,
and performance. To achieve all that we have carbon nanotubes and nanotube
transistors. This paper gives the insight in the working and content of
Nanotube.
Even for the non-computer buffs among us it is hard to escape the rapid
increase in computer speed and power that has occurred over the last twenty
years since personal computers were introduced into the market. What once
required a room full of equipment now can be done using a device held in the
palm of your hand. This transition has occurred because of technical
improvements in the design and manufacture of two major integrated circuit
(IC)—based components: microprocessors and memory devices. The present
generation of interconnect technology is based on 0.25 micron
conductors—representing a maximum of about 500 megahertz in processor speed.
The goal for 2006
is 0.1 micron conductors which will open the door for processor speeds into the
gigahertz region. However, for technical reasons, this rapid increase in
computing capability was anticipated to come to an end with the present
generation of ICs due to the limitations of interconnect technology. As one
might expect, this thought struck fear into the semiconductor and computer
industries and has been the subject of an all out effort on the part of the
industries and their various research associates for a number of year.
Computers use RAM to hold the program code and data during
computation. A defining characteristic of RAM is that all memory locations can
be accessed at almost the same speed. Most other technologies have
inherent delays for reading a particular bit or byte.
Early main memory systems built from vacuum tubes behaved much like modern RAM,
except the devices failed frequently. Core memory, which used wires attached to
small ferrite electromagnetic cores, also had roughly equal access time. The
basic concepts of tube and core memory are used in modern RAM implemented with
integrated circuits.
Alternative primary storage mechanisms usually involved a non-uniform delay for
memory access. Delay line memory used a sequence of sound wave pulses in
mercury-filled tubes to hold a series of bits. Drum memory acted much like the
modern hard disk, storing data magnetically in continuous circular bands. Many
types of RAM are volatile,
which means that unlike some other forms of computer storage such as disk
storage and tape storage; they lose all data when the computer is powered down.
Modern RAM generally stores a bit of data as either a charge in a capacitor, as
in “dynamic RAM”, or the state of a flip-flop, as in “static RAM . In
the summer of 2003, a 128 KB Magnetic RAM chip was introduced, which was
manufactured with 0.18 µm technology. The core technology of MRAM is based on
the magnetic tunnel effect. In 2004, Infineon technologies unveiled a 16 MB
prototype based on 0.18 µm technology once again.
Currently,
there are several types of non volatile RAM under development, which will
preserve data while powered down. Technologies that are being used include
carbon nanotube technology and magnetic tunnel effect.
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