A method is provided, wherein a virtual internal master clock is used in connection with a RISC CPU. The RISC CPU comprises a number of concurrently operating function units, wherein each unit runs according to its own clocks, including multiple-stage totally unsynchronized clocks, in order to process a stream of instructions. The method includes the steps of generating a virtual model master clock having a clock cycle, and initializing each of the function units at the beginning of respectively corresponding processing cycles. The method further includes operating each function unit during a respectively corresponding processing cycle to carry out a task with respect to one of the instructions, in order to produce a result. Respective results are all evaluated in synchronization, by means of the master clock. This enables the instruction processing operation to be modeled using a sequential computer language, such as C or C++.