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This paper proposes a routing algorithm for the interconnection of multiple processors based on the shortest-path and deflection-routing principles. The routing algorithm, named SPDRA (Shortest Path and Deflection Routing Algorithm), is applied to multiprocessor systems with a single-stage shuffle physical topology. SPDRA is general-purpose, as opposed to the majority of routing algorithms for multiprocessor systems which are optimized for particular traffic patterns generated by a restricted class of parallel algorithms. The general-purpose nature of SPDRA allows perfomance comparisons with a wide class of routing algorithms for multiprocessor systems that, similar to the single-stage shuffle physical topology, have a fixed node-to-processor ratio. The paper compares SPDRA with hypercube algorithms for bidimensional meshes and torus physical topologies, routing algorithms for hierarchical tridimensional tori, and algorithms for routing permutations in shuffle networks, which constitute the most widely accepted approaches for multiprocessor interconnection. SPDRA exhibits a performance advantage for a broad range of network sizes and, in general, the performance advantage grows as the number of processors increases. However, this paper compares the SPDRA algorithm against a limited set of multiprocessor systems and does not demonstrate a general superiority of SPDRA over all systems with a fixed node-to-processor ratio and, especially, with a growing node-to-processor ratio, such as multistage networks.