Abstract: A computer process transforms a "general purpose" central processing unit (hereinafter "CPU") into one of a number of possible "special purpose" CPUs by changing operation of circuitry in the CPU. Changing operation of CPU circuitry as described herein "fine tunes" behavior of the CPU, e.g. provides resources and environment most suitable for execution of a specific application program, or even a portion of an application program. The computer process performs the steps of: checking whether the CPU has a tunable unit, waiting for a triggering event indicating a need for fine tuning, reading one or more statistics on the performance of the CPU, comparing the read statistics with corresponding predetermined statistics, determining a multi-valued parameter signal depending on the comparison, driving the determined parameter signal to the tunable unit and changing operation of circuitry in the tunable unit depending on the received parameter signal, thereby to fine tune operation of the tunable unit and the CPU.