An electronic energy meter is described. The meter includes, in one form, voltage and current sensors having their outputs coupled to an analog to digital converter. The digital signals output by the converter are supplied to a digital signal processor (DSP) which outputs digitized metering quantities to a microcomputer. Using the metering quantities supplied by the DSP, the microcomputer performs additional metering calculations and functions. In one aspect, the present invention is directed to a method for determining whether an option board is being used and, if so, controlling meter operations in accordance with the coupled option board. In another aspect, the present invention is directed to a high function option board which, when enabled, operates as a master and the meter microcomputer automatically switches from its normal master mode to slave mode. In yet another aspect, the present invention is directed to converting the functionality of the electronic electricity meter from a first mode of operation to a second mode of operation. In still another aspect, the present invention is directed to a structure for avoiding, or minimizing, the loss of billing data when converting, or upgrading (or downgrading), meter operations.