A memory, a data processing system comprising a memory, a method of operating a memory and a memory compiler apparatus and method of memory compilation are provided, which relate to a memory comprising data storage circuitry to store data values at data locations. Addressing circuitry is provided to access the data value at a storage location in dependence on a received address and readout circuitry to provide an output value in dependence on the accessed data value. The memory further comprises scrambling circuitry to select at least one of: a mapping between the address and the storage location; and a mapping between the data value and the output value, in dependence on a received scrambling value. The mapping between the address and the storage location and/or the data value and the output value can thus be easily and rapidly changed.