Patent ID: 7730375

Claim:
A method of operating an electronic device having a functional operation mode and one or more test operation modes, the method comprising the steps of: (a) causing the electronic device to enter the functional operation mode directly after powering up, said electronic device having neither unused external connections nor externally applied functional operation mode control codes unused in controlling the functional operation mode; (b) while in the functional operation mode and without interfering with the functional operation mode operations, monitoring one or more predetermined input connections of the electronic device for the presence of predetermined non-functional logic level stimulus; (c) monitoring one or more other predetermined inputs for other logic level stimulus when the electronic device is designed to operate in more than one test operation mode; (d) upon detecting predetermined combinations of logic level stimulus in steps (b) and (c), entering a specified one of a number of test operation modes; (e) operating in the test operation mode entered in step (d) while simultaneously monitoring predetermined inputs of the electronic device for the presence of at least one predetermined logic level stimulus test control code for causing the electronic device to exit operation in the test operation mode entered in step (d); and, (f) then, returning to the functional operation mode.