This case study illustrates the application of a software development process that is intended to produce low-defect code for reliable systems. Recognizing that traditional testing is conducted too late in development to ensure the quality of mission critical software, the process emphasizes verification through applying formal methods, inspections in all phases, and a unique testing philosophy. This process is demonstrated in a well instrumented candidate project that is the subject of the case study. The product is control software for a robotic data tape system used in the B-2 test program. Only three defects were found in the unit and integration test phases of the project, despite being over 7,000 lines of code in size. Since deployment, no major defects have been found in more than eight months of operational use.