Integrated-circuit radio

An integrated-circuit radio communication device (1) comprises a processor (7), memory (13), and radio communication logic (17). The memory (13) has a firmware module (23) stored at a firmware memory address, the firmware module (23) comprising instructions for controlling the radio communication logic (17) according to a predetermined radio protocol. The processor (7) is configured to receive supervisor call instructions, each having an associated supervisor call number, and to respond to a supervisor call instruction by (i) invoking a supervisor call handler in the firmware module (23), and (ii) making the supervisor call number available to the call handler. A software application (27) is loaded into the memory (13) of the device (1), and stored at a predetermined application memory address. It is arranged to invoke a radio communication function from the firmware module (23) by issuing a supervisor call instruction having an associated predetermined supervisor call number corresponding to the function to be invoked.