Hand-held data capture system with interchangeable modules

A hand-held data collection terminal unit comprising:

• a base module having a housing including a user input and output means, the base module including a first microprocessor circuit for controlling the functions of the base module, and for communicating data and control signals to and from the base module according to a predetermined operational mode of the first microprocessor circuit of the base module;
• means, forming part of the base module, for receiving and for mounting and electrically and communicatively coupling a data and communication module to the base module;
• and
• a data and communication module comprising a second microprocessor circuit and an interface circuit, the second microprocessor circuit being coupled to the interface circuit and coupled between the interface circuit and the first microprocessor circuit of the base module, the second microprocessor circuit in combination with the interface circuit capable of emulating data communication between the first and second microprocessor circuits according to the predetermined operational mode of the first microprocessor.