Reliability assessment of a modern RISC microprocessor in the space radiation environment

Commercial reduced instruction set computing (RISC) microprocessors are appearing in military and space designs because they have many favorable attributes. RISC processors are immensely complex devices containing millions of logic gates and internal storage elements such as registers and cache memory. These storage elements are susceptible to ionizing radiation in earth orbit. Energetic protons and heavy ions may upset data in these storage elements or may cause destructive component failures such as latch-up. The thesis presents radiation test data for the Motorola XPC7455 RISC microprocessor. The thesis identifies sources of experimental error and compares methods of predicting the processor's reliability in Earth orbit. The thesis presents a sensitivity analysis that considers variations in radiation shielding, sensitive volume geometry, orbit parameters and space weather environment. The thesis analyzes the failure modes for the processor and provides a framework for evaluating the processor reliability.