A data processing circuit comprises a register file (14) having read ports and write ports. A plurality of functional units (21a-c), is coupled to receive operand data from a same combination of read ports. Each functional unit is coupled to a respective one of the write ports for writing a respective result. An instruction issue slot has outputs (11) for supplying register selection information to said combination read ports and to the respective ones of the write ports. The output of the issue slot also supplies an operation code. The functional units (21a-c) in the plurality are arranged to respond to at least to one value of the operation code by each executing a respective operation using the same operands from said same combination and each functional unit producing a respective result at a respective ones of the write ports.