Abstract: An apparatus and method for counting event signals generated by a computer system is described. The event signals are indicative of the performance of the computer system. Programmable logic enhances the functionality of performance counters by enabling the system user to specify, during the execution of an application program, which event signals to count. The system user can dynamically configure the programmable logic to select a subset of the event signals generated by the computer system, and to combine the selected subset of event signals to generate a new event signal that can be counted. Other new event signals can be generated by the programmable logic from the selected subset of event signals. A user of the computer system can dynamically make the selection of any one of the new event signals for counting.