An electronic weighing scale system capable of performing a plurality of functions. Predetermined subsets of the functions can be accessed from the system keyboard. The subset of functions which a particular keyboard can access is easily changed by replacing a non-volatile memory integrated circuit chip which may be the same one that contains postal rate information. Memory locations within the chip are segregated into two complementary arrays, one containing each possible combination of strobe and return signals, and the other containing a different word which defines one of the functions that the system can perform. When a particular key is actuated, the strobe/return signal output from the keyboard is compared with each of the strobe/return combinations stored in the first array. When a match is found, a function identification word is retrieved from the corresponding memory location in the second array to designate the specific function that the actuated key is intended to produce.