Abstract: A portable data processing apparatus and its peripheral apparatus are disclosed. A battery compartment includes an electrical connector communicatively coupled with one or more processors, and the battery compartment and an electrical connector are adapted and dimensioned such that a detachable cover is replaceable with a peripheral apparatus, which, when installed in place, functions as the cover of the battery compartment, and the one or more processors become communicatively coupled through the electrical connector with an electrical counterpart connector of the peripheral apparatus.