The increasing reliance on embedded processors in safety-critical and mission-critical domains such as automotive systems, industrial control, aerospace, and harsh-environment electronics has fundamentally transformed the expectations placed on computing hardware. Modern microprocessors are no longer evaluated solely on performance and energy efficiency, but also on their ability to maintain correct operation under adverse conditions, including radiation-induced soft errors, permanent hardware faults, aging effects, and extreme environmental stress. This article presents an in-depth, theory-driven research analysis of architectural strategies for achieving fault tolerance and functional safety in processor-based systems, with a particular focus on lockstep architectures, redundancy-based designs, and the exploitation of embedded hardware features for error detection and recovery. Drawing strictly on the provided body of scholarly and industrial references, the paper synthesizes knowledge spanning low-cost fault-tolerant processor deployment, dual-core and triple-core lockstep mechanisms, trace and debug-based fault resilience, and hybrid error-detection schemes for modern microcontrollers and microprocessors. The methodology adopted is a qualitative, architecture-centric analysis that integrates comparative reasoning across industrial implementations and academic proposals. The results highlight that fault tolerance is not a monolithic design choice but a layered architectural philosophy, where redundancy, monitoring, and recovery mechanisms must be coherently aligned with application safety requirements such as ASIL D. The discussion critically examines trade-offs between cost, complexity, coverage, and scalability, and identifies persistent limitations related to common-mode failures and design-time assumptions. The article concludes by outlining future research directions toward adaptive, analytics-driven safety architectures that merge functional safety and cybersecurity considerations in next-generation embedded systems.

Fault tolerance, lockstep processors, functional safety, safety-critical systems

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