Abstract: Disclosed is an expandable calculator system of the type implemented on semiconductor chips providing additional data storage registers for increasing data storage capacity of the basic system. A basic calculator system comprising two semiconductor chips is provided with additional semiconductor chips each providing a plurality of separately addressable registers for storing data, to thereby increase the data storage capacity of the two-chip system. First and second control signals synchronize the internal timing of the external register chips and also enable communication to the external chips. The data system has 10 registers which are addressed by means responsive to instructions communicated via the data transmission path. A first set of data word digits is read into the appropriate memory, then right shifted, and then another set of data word digits are read in. Means are provided for clearing all registers on one chip of the internal register chip set.