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9
NANOSCALE STANDARD
DIGITAL MODULES
Shiva Navab
In this chapter on employing the computing features of spin waves, we present
several nanoscale standard combinational modules. We show that a number of
these widely used arithmetic and logic modules, including full adders, multipliers,
decoders, encoders, multiplexers, and demultiplexers, can be implemented by
employing the concurrent write feature and superposition property of the spin
waves. In addition, we demonstrate how to implement more complex modules,
such as priority encoders and shifters, by using spin-wave switches. The univers-
ality of the presented digital architectures ensures the possibility of realizing any
logic switching functions. Moreover, these nanoscale modules can be integrated
by adding latches to implement sequential systems.
9.1. INTRODUCTION
The significance of efficiently implementing standard combinational arithmetic
and logic modules is due to the fact that they are the basic blocks of any digital
system. All the sequential systems can be implemented by just adding latches to
the combinational circuit. The universality of the combinational modules ensures
the possibility of realizing any logic switching function. A set of combinational
modules are said to be universal if any combinational system can be implemented
using the elements from just that set. In addition to logic gates such as {NAND}
and {NOR}, standard combinational modules can generate universal sets as well.
For instance, a network of multiplexers can implement any switching function
according to Shannon's decomposition [1]; therefore the set {MUX} is universal.
{Decoder, OR} is another example of a universal set. We show how each of these
modules can be implemented using spin waves.
 
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