The quad programmable line card signal processor consists of four independent channels of codec and digital signal processing functions on one chip. In addition to the classic A-to-D and D-to-A conversion, the device includes termination impedance synthesis and a 64-tap echo canceller, functionally, on a perchannel basis. The device is capable of meeting all international standards for terminating impedance and digital encoding format. The processing circuitry for the adjustment of the transmit level (equalization) to accommodate current-sensing SLICs is also included.