The Roland D-50 was an extremely popular polyphonic digital synthesizer from Roland produced from 1987-1990. The D-50 competed directly against the immensely popular Yamaha DX-7 but its architecture was completely different. Using Roland's patented 'LAS' or Linear Arithmetic Synthesis which incorporated sample playback combined with digital synthesis / resonant filters resulting in a synthesizer capable of the percussive and glassy sounds made popular by FM synthesis but was also capable of analog and traditional style sounds.