An application-specific implementation of an encoder counter designed for maintainability

An encoder counter was designed, fabricated, and tested using advanced technologies. The application-specific integrated-circuit (ASIC) design included a self-diagnosing semicustom LSI controller chip and four programmable logic devices (PLDs). The design enhanced system reliability by at least a factor of 2 over a more traditional approach using SSI and MSI parts since the increased integration of this ASIC design reduced both the total chip count and the complexity of the printed circuit board layout. In addition, the self-diagnosing circuitry improved maintainability by at least a factor of 2 over a design without such capability since, after a failure has occurred, less troubleshooting time will be required. However, several of the advanced LSI chip functions could not be utilized owing to a circuit failures. These unused features would have further augmented system maintainability and reliability