MU5 is a high speed general purpose computer designed to meet the requirements of high level languages. The order code is such that several distinct operations are involved in accessing an operand. Operands specified directly by instructions are accessed by the instruction processing unit described in this paper. This unit is designed as a pipeline in which several instructions are in different stages of processing at any one time. A significant improvement in performance is obtained by this technique although detailed requirements of the order code deteriorate the performance in practice. An assessment of the expected overall performance is given.