A step-by-step tutorial of the methods and tools used for the reliability analysis of fault-tolerant systems is presented. Emphasis is on the representation of architectural features in mathematical models. Details of the mathematical solution of complex reliability models are not presented. Instead the use of several recently developed computer programs--SURE, ASSIST, STEM, PAWS--which automate the generation and solution of these models is described. Butler, Ricky W. and Johnson, Sally C. Langley Research Center ARCHITECTURE (COMPUTERS); COMPUTER PROGRAMS; CONTROL SYSTEMS DESIGN; FAULT TOLERANCE; MATHEMATICAL MODELS; REDUNDANCY; RELIABILITY ANALYSIS; FAILURE ANALYSIS; FAULT TREES; MARKOV PROCESSES; SYNTAX...