ABSTRACT
Computers are intrinsically probabilistic machines, constrained by the reliability of their algorithms and component physical parts. This chapter explores some of the solutions to noise and defects in nanocomputers and their limitations in the context of physics. There are some parallels to these solutions in the brain, with implications for nanocomputer architecture and its perhaps ultimate synthesis with neural systems. In analysing the effects of faults on nanocomputation, the chapter considers separately the effects of device defects on computation and, more fundamentally, the effects of noise on representation, communication and computation in information systems. The basic approach to any kind of fault tolerant computation is to implement redundancy in either space, time or both. Communication is the process of information transmission across space and/or time, the measure of information being the bit. Representation is the physical implementation by which a single bit, the minimum measure of information, is characterized in spacetime.
