Yamaha XG

Yamaha’s extension to the General MIDI standard, released in 1994. It increased the number of available instruments from 128 to over 600, all controllable via standard MIDI controller messages, and it increased polyphony from 24 to 32 voices. It is backward compatible with the General MIDI standard, but it is not compatible with the Roland GS expansion to the General MIDI standard. The XG standard is widely supported by Yamaha, Korg, and music software, but no other hardware manufactures have adopted it.