The Silicon Optic Nerve

  • Misha Mahowald
Part of the The Springer International Series in Engineering and Computer Science book series (SECS, volume 265)


Communication among neuronal elements is a significant limiting factor in the design of VLSI neuromorphic systems. This fact is not surprising given that a large percentage of the volume of the nervous system is composed of myelinated axons. The degree of convergence and divergence of single neurons is staggering in comparison with human-made computers. It might appear impossible, even in principle, to build such structures in VLSI circuits, which are limited to a two-dimensional plane of silicon. Surprisingly, the cortices of the brain are nearly two-dimensional as well. In fact, we cannot increase the degree of connectivity in a system whose wires occupy space by employing a structure in which nodes are arrayed in three dimensions [97]. There is nothing fundamental about the structure of neural tissue that cannot be embedded in silicon. The thickness of cortical structures can be represented with a correspondingly larger silicon surface area. However, silicon surface area is available on small die, which are several millimeters on a side, and so the number of neurons that can be fabricated on a single die is limited. Consequently, connections between silicon neurons located on different chips are essential for building even moderately sized artificial neural systems. This chapter introduces a general method for interchip communication that is tailored for use in neuromorphic systems.


Delay Line Address Event Select Signal Initiation Node Global Address Space 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.


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  1. 2.
    Mortara and Vittoz have analyzed the probability of collision between random events and the influence of collisions on accuracy of data transfer [73].Google Scholar
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    The arbiter was designed, and the basic circuit element was analyzed, by Massimo Sivilotti [97].Google Scholar
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    Using conservative estimates, Sivilotti [97] calculated that safe arbitration could be achieved if the P3/P4 transistors were six times stronger than N3/N4.Google Scholar

Copyright information

© Springer Science+Business Media New York 1994

Authors and Affiliations

  • Misha Mahowald
    • 1
  1. 1.M.R.C. Anatomical Neuropharmacology UnitOxfordEngland

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