A method for performing neural network processing, and a corresponding data processing system. The data processing system is configured to define one or more tiles for use when reading a portion of an input feature map from memory or writing a portion of an output feature map to memory. The data processing system is also configured to provide information which allows positions falling within the defined one or more tiles to be mapped to memory locations to allow a processor to read data for an input feature map from memory or to write data for a portion of an output feature map to memory.