The transition to manycore systems is arguably the greatest challenge facing the ICT industry, Computational Science, and Computing Science research. The challenge is globally recognised, and is an EPSRC ICT priority: Manycore Architectures in Distributed and Embedded Systems (MACDES). The proposed network will identify and bring together a critical mass of UK manycore researchers. The manycore revolution is fundamentally changing multiple levels of the computation execution stack: from processor architecture, through systems software, to applications. The UK has world leading researchers and industrialists working on specific technologies at each level, but currently researchers and engineers do not collaborate adequately on the complex manycore challenges. Furthermore, meaningful industry engagement is limited, despite the large number of UK-based industrial research labs with strategic interest in manycore systems. We will foster effective communication between academic and industrial research teams both at different levels in the execution stack (e.g. compiler developers targeting an emergent architecture), and within each level (e.g. program analysis applied to improve memory access latency in the systems layer). The teams will benefit by being able to identify and exploit synergies and opportunities for cross-pollination. We will establish well defined, highly available channels for communication and low-overhead mechanisms for collaboration. Given that many world-class UK researchers are isolated in relatively small departments and research groups, the network will enable national sharing of ideas, information and infrastructure. Community support and resource pooling will enable UK researchers to achieve greater academic impact globally, competing effectively with larger, well-resourced groups in the USA (e.g. Aspire Lab at Berkeley), China (e.g. State Key Lab of Computer System and Architecture, Chinese Academy of Sciences), and elsewhere. Both architectural innovation and systems software development are massive investments, often involving person-decades of effort. MaRIONet will enable sharing of expertise and infrastructure to lower the barrier to entry for UK systems researchers working in this area. Industrial network partners will gain exposure to cutting-edge research, and ideas to address current problems. Academic partners gain real-world use cases and grand challenges. At least three of the UK Policy Exchange `Eight great technologies' are directly enabled by the increased scale and speed of future manycore systems and software, namely: * Big Data revolution: enabled by manycore systems for energy-efficient collection, analysis and storage of big data. * Robotics and autonomous systems: enabled by manycore systems for artificial intelligence, planning, image recognition, humanoid motion control. * Synthetic biology: enabled by manycore processing of biological data, in-silico simulation of bio-mechanisms. Hence we anticipate that future UK economic growth and societal well-being will be strongly influenced by manycore technology, which is the focus of our research network.