A register data store(20) is provided within a data processing system(2). The register data store(20) may be accessed via registers for which a data processing instruction specifies a register size Q, D and a data element size S16, S8 for the multiple SIMD data elements to be manipulated by that data processing instruction. A given data processing element may be accessed via different registers depending upon the mapping between the register specifier, the register size and the data element size to a particular location within the register data store(20). |