A series of portable mp3 players introduced by Diamond Multimedia (which became SonicBlue after merging with S3). The PMP300 was the first portable mp3 player ever sold, with a price over $100 for a 32MB unit that was only expandable with then-expensive Smart Media cards, and even then only to 64MB. It had a vestigal menu button that just messed up the screen and could only display about as much track information as your average Discman, but they sold well. Other Rio models include the Rio Volt (an mp3 CD player) and the Rio Riot (a hard disc-based mp3 player). | 
