A method and apparatus for selectably providing single-ended and differential signaling with controllable impedance and transition time is provided. According to the method and apparatus, a differential signal can be transmitted over two wires or two single-ended signals can be transmitted over the two wires. According to the method and apparatus, termination may be selected among a single-reference termination, a center termination, or a high-impedance termination. Regardless of the type of termination selected, a capability for dynamic control of the termination impedance is provided. Moreover, an ability to change impedances of termination elements to maintain a desired termination impedance for both single-reference termination and center termination modes by shifting bits is provided. Also, a capability for dynamic control of transition times of signals is provided.