Configurable integrated circuit having true and shadow eprom registers

Abstract

A configurable integrated circuit includes a first register having N EPROM cells, and a second register having N EPROM cells, each EPROM cell in the second register corresponding to a distinct one of the N EPROM cells in the first register. Register programming circuits store a set of N binary configuration values in the first register and store boolean complements of the N binary configuration values in the second register. N configuration value sensing circuits are used to read the EPROM cells and generate N configuration signals. Each configuration value sensing circuit is a set/reset latch coupled to one EPROM cell in the first register and the corresponding EPROM cell in the second register. Under normal operating conditions, the latch generates a configuration signal corresponding to the configuration value stored in the one EPROM cell in the first register. A strengthening circuit protects the sensing circuit from alpha particle radiation by applying a strengthening current to each latch after the latch has already reached a stable state. The configurable integrated circuit has a multiplicity of configurable circuits, each configurable circuit having at least one transistor that receives at least one of the N configuration signals and configures the configurable circuit in accordance therewith.