The Interleaved Signature Instruction Stream (ISIS) is a signature embedding technique that allows signatures to co-exist with the main processor instruction stream with a minimal impact on processor performance, without sacrificing error detection coverage or latency.
While ISIS incorporate some novel error detection mechanisms to assess the integrity of the program executed by the main processor, the limited number of bits available in the signature control word question if the detection mechanisms are effective detecting errors in the program execution flow. Increasing the signature size would negatively impact the memory requirements, so this option has been rejected. The effectiveness of such mechanisms is an issue that must be addressed. This paper details those checking mechanisms included within the ISIS technique that are responsible of the assessment of the integrity of the processor execution flow and the experiments carried out to characterize their coverage.