Abstract: Apparatus 70 interfaces between port 20 of personal computer 10 and peripheral device 40 connectable to port 20. Transmit and receive data signals (TXD, RXD) are transmitted and received between port 20 and device 40 to pass through without substantial modification by apparatus 70. Protocol signals are transmitted by port 20 and processed to provide digital data signals. The protocol signals include a Request To Send (RTS) signal and a Data Terminal Ready (DTR) signal, whereby the apparatus processes RTS signal to provide a protocol clock signal and processes DTR signal to provide a protocol data signal. The protocol signals are monitored to identify a protocol signal pattern. Upon identifying such pattern within a particular protocol signal, a particular digital data signal is extracted from the protocol signal. The extracted digital data signal may then be converted to analog signals which are applicable to produce sound from speaker 80.