Encoders and decoders for encoding and decoding data according to a coding scheme. The encoder converts N bits of input data into M voltage signals for transmission over M parallel wires to a decoder having one or two decoding stages that recover the N bits of data from the M voltage signals. The coding scheme is an N-bit, M-wire PAM-Q code in which each voltage signal wi has one of Q voltage levels l1-lQ, where l1