Roland's first digital synthesizer model, introduced in 1987. Designed specifically to compete with Yamaha's DX-7, the D-50 used a rather odd hybrid voice architecture. It appears that Roland may have considered a rompler architecture, but memory was too expensive at the time. So they devised an approach called "Linear Arithmetic"; this involved ROM samples of short attack transients, which the synth spliced together with waveforms from a sort of virtual analog wave generator. This then went through a digital lowpass filter algorithm and digital VCA in conventional fashion. The synth was 16 voice polyphonic, and up to four-way layering was possible.