Reconfigurable Triple Modular Redundant and N-Modular Redundant systems with variable Reliability in multi-processor environment

Voting Logic (VL) is an important component of Triple Modular Redundant (TMR) and N-Modular Redundant (NMR) systems. A number of voting logic designs are presented in this paper. The Design Profile, Diagnosability and Reliability calculation of a word voter for TMR system is presented. The notion of reconfiguring a 4 processor design for an “unconventional” TMR and 4MR mode is introduced. Reconfiguration is implemented on the fly using a “reconfiguration instruction” with the “ON” operand in the normal program code. Processors and VL for TMR are chosen using metrics such as millions of instructions executed for processors and reliability of the VLs. The TMR or 4MR configuration can be “dissolved” by the same reconfiguration instruction with the “OFF” operand. The major contribution is the Dynamic Reconfiguration of the processors at run time for enhanced Reliability (unlike all other systems where Reliability is always a decreasing function of time). The second contribution is that TMRs are built and dissolved during normal operation, unlike original TMRs which are hard wired for lifetime operation.