Reliable computation in computing systems designed from unreliable components

This is the second of two papers which present information-theory-type results pertaining to the reliability of computing systems designed from unreliable components. Two models for component malfunctions are considered. The first is based on the assumption that malfunctions of a particular component are statistically independent from one use to another. The second is based on the assumption that components fail permanently but that the components which have failed are periodically replaced with good ones. In both cases, malfunctions in different components are assumed to be independent. Just as a channel capacity is defined for communication channels, a computing capacity is defined for computing systems. For both component failure models, it is shown that there are computing systems, designed entirely from unreliable components of the assumed type, which have nonzero computing capacities.