Coming Home 8-bit is one of the musical Easter eggs in Call of Duty: Black Ops on the Zombies map Moon. It also appears as one of the musical Easter eggs on Nuketown Zombies of Call of Duty: Black Ops II and as background music in Dead Ops Arcade 2: Cyber's Avengening in Call of Duty: Black Ops III.
Activating the Song
On Moon, the song is activated upon the player pressing use on some computer equipment that can be found at the end of Tunnel 11 next to the radio near the power room door.
On Nuketown Zombies, it is activated up on the players shooting or knifing all of the heads off of the Mannequins around the map.