The SpiNNaker (Spiking Neural Network Architecture) platform has been developed to support real-time modelling of large-scale biological neural networks. It currently incorporates half a million (soon to be a million) ARM processor cores with a bespoke interconnect fabric specifically designed to enable the very high connectivity of biological brains to be modelled. As neuron and synapse models are implemented in software, SpiNNaker is very flexible, and it can be used to model novel neuron models and learning rules. The SpiNNaker platform is openly accessible under the auspices of the EU Flagship Human Brain Project, and is currently being used to support a wide range of neuroscientific research. The HBP is also supporting the development of a second generation machine.