We discuss the inherent capacity limits and code design issues surrounding
the implementation of reliable computation of Boolean functions in
nano-circuit fabrics characterized by extremely high densities of permanent
defects. A technology based on carbon nanotubes FETs appears to be the most
likely candidate for near-term acceptance. In the face of challenges posed
by these devices, we study the density with which functions can be packed into
this fabric incurring low probability of error, The unique and novel property of
our study is the use of the inherent structure of Boolean functions, specifically 
of the existence of all large fraction of ``don't-care'' states in the Boolean
functions being implemented.