A communication adapter includes a cable communication signal processing circuit
which enables a PDA to have access to a communication network via a cable and a
radio communication signal processing circuit which enables a PDA to have access
to a communication network via radio waves. The cable communication signal processing
circuit and the radio communication signal processing circuit are provided in a
single case or on a single board. The cable communication signal processing circuit
and the radio communication signal processing circuit operate simultaneously. By
attaching the communication adapter to a PDA, the PDA can have access to the communication
network via the cable and to make an access to the communication network via the
radio waves. Further, the PDA is capable of communicating with the network via
the cable and via the radio waves simultaneously.
