RS-232 Recommended Standard 232 This was originally a nine-wire interface standard for teletype machines from the Electronics Industry Association. Now in its third revision (RS-232-C), it's the standard for computer serial-port transfers. The RS-232 standard is probably the only computer component that's 40 years old and still working. One wire is used as the ground; the rest are dedicated to detecting carrier signals, managing the timing of data transfer, oh, and sending and receiving data.