An analysis of fault effects and propagations in ZPU: The world´s smallest 32 bit CPU

This paper presents an analysis of the effects and propagations of transient faults by simulation-based fault injection into the ZPU processor. This analysis is done by injecting 5800 transient faults into the main components of ZPU processor that is described in VHDL language. The sensitivity level of various points of ZPU processor such as PC, SP, IR, Controller, and ALU against fault manifestation is considered and evaluated. The behavior of ZPU processor against injected faults is reported. Besides, it is shown that about 50.25% of faults are recovered during simulation time; 46.47% of faults are effective and the remainders 3.28% of faults are latent. Moreover, a comparison of the behavior of ZPU processor in fault injection experiments against some common microprocessors is done. The results will be used in the future research for proposing a fault-tolerant mechanism for ZPU processor.