An integrated circuit for a memory input/output (I/O) pin has five different modes of operation. The memory chip is enabled to operate with unbuffered (or registered) dual inline memory modules (DIMMs) as well as fully buffered DIMMs. A T-coil circuit equalizes the capacitive loading of the high-speed functions. An exemplary embodiment provides a memory chip containing a multi-functional physical I/O circuit that can act as power or ground; as a DDR2 or DDR3 interface; as a high-speed differential receiver; or as a high-speed differential transmitter.