The Vectrex is interesting because it contains BIOS routines for music playback. OK, so that's nothing special, but what is perhaps more interesting is that a set of 13 tunes are hardcoded as part of (what I assume is) the BIOS RAM. One of them is the startup sound, of course, but the other 12 were used by programmers who didn't want to program their own music into games. So they just used one of these 12 tunes for their game. I find this idea fascinating - to pre-write music and hardcode it into a system.
Are there any other examples of this sort of thing that people know of? Or is this a common occurrence?