system name:Mega Drive
  bus
    rom name=tmss.rom size=0x800
    ram name=work.ram size=0x10000 volatile
  apu
    ram name=audio.ram size=0x2000 volatile
  vdp
    ram name=video.ram size=0x10000 volatile
    ram name=palette.ram size=0x80 volatile
    ram name=vertical-scroll.ram size=0x50 volatile
  psg
  ym2612
