A processing system includes a pair of processor coupled in a lockstep arrangement. The pair of processors is coupled to a storage element that is external to the both of them. Each processor executes an instruction stream that is identical to that executed by the other. Dissimilar information can be exchanged between the processors by each writing the information they wish to exchange to a first storage location with identical instructions. Although both processors execute the write with the same address, the information written by one of the processors is redirected to a second storage location. Each processor then reads the first and second storage locations to retrieve information supplied by the other processor. Now each processor has a copy of the other's data while staying in lockstep.