Hey, I know this comment is months later, but I thought I might add a bit. The Wikipedia mentions 1981's Frogger as the earliest example, but it's possible there might be some slightly older examples on the Atari 2600. Although with the 2-channel sound generation, it's rather limited in terms of what you could really call music. The examples that I can recall however, like Mountain King, Moon Patrol, or Pitfall II, do come later than Frogger. I still believe there may be older examples either in the arcades or home console.