Abstract: A customizable integrated circuit device is disclosed that is capable of having unique data selected for controlling the functionality or configurability of the integrated circuit. The integrated circuit device has a microcontroller unit, a plurality of function units, coupled to the microcontroller unit, and a novel customization logic unit, also coupled to the microcontroller unit. A plurality of signal selectors, further coupled to the customization logic, either on the integrated circuit or on the mounting module to which the integrated circuit is afixed, are selected to control a signal generated by the customization logic to the microcontroller. The customization logic unit may use data that represents a serial number, performance characteristics, such as operational speed, or qualified external working configurations, such as mainstore or caching configurations, associated with the integrated circuit and as selected by the signal selectors.