Abstract: A method for monitoring at least one internal signal of an integrated circuit (IC), which includes a first input/output (I/O) end set and a second I/O end set, includes providing a mode selection mechanism for placing the IC under operation mode or monitor mode, inputting or outputting a data signal set from the first I/O end set and an address signal set from the second I/O end set under the operation mode; and under the monitor mode, inputting or outputting a composite signal set including data and addresses from the first I/O end set, obtaining the addresses of the composite signal set from at least one first end of the first I/O end set, multiplexing the internal signal for output to at least one second end of the second I/O end set, and monitoring signals from the second end to monitor the internal signal.