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Results are reported which are of interest in the automatic adaptive equalization of telephone lines or other narrowbandwidth channels where data transmission is limited primarily by intersymbol interference. We describe an algorithm for adjusting the tap gains of a tapped delay line (TDL) equalizer which converges for all channels to the setting, which minimizes the mean-square error (rose) at the filter output due to both noise and intersymbol interference. This algorithm has been implemented using digital microcircuits and metal-oxide semiconductor (MOS) shift registers to construct a 63 tap all-digital TDL filter covering 19.7 ms. The modulation system used is vestigal sideband with bandwidth 1.6 kHz. The data rate is 3200 pulses/s, or 9600 bit/s with 8 data levels. A description of the hardware realization and performance data over various telephone lines is given.