The Rio Carbon is a line of digital audio players that was produced by the now defunct Rio from 2004 to 2005. It was similar in size, capacity, and cost with Apple's iPod Mini which debuted earlier the same year. This was Rio's second player to use a miniature hard disk for storage, after the Rio Nitrus, which was first to market with a 1.5 GB drive in late 2003. History The Carbon was announced on August 2, 2004. The first 500 Carbons were produced as a Limited Edition with a unique serial number (1-500) that was laser engraved into the polished steel (back) side of the player. The initial Carbon was silver with a 5 GB drive and retailed US $249.99, same as the iPod Mini with 4 GB. An off-white version called the Carbon Pearl was next, with a 5GB drive at first and then a 6 GB drive later as the price of Microdrives fell. This was followed by the 2.5 GB ce2100 (black) and ce2110 (light green) which offered reduced features and cost. An 8 GB model with a colour screen was planned, code-named Avalon, but was never produced due to the demise of Rio in August 2005. Rio officially exited the portable music player market in August 2005 and is no longer providing firmware updates for the players. The last officially released version of the firmware (1.95) supports subscription-based and purchased PlaysForSure licenses. A previously unreleased version of Rio Carbon firmware, called "The Developer's Cut", was released in January 2006 by enthusiasts, and offers several new and updated features. Features The Carbon features a microphone and a bidirectional wheel, which is used for scrolling and adjusting volume, along with a 5-way navigation pad. It is small in size (82 x 61 x 13 millimeters) and weigh 3.2 ounces, and is powered by a non-removable rechargeable lithium ion battery that has up to 20 hours of playback time. The wheel is notched. Either the 5-way navigation pad or the scroll wheel and the menu button can be used independently to navigate through menus or they can be used together. The two have different behaviors, and are therefore complementary, not redundant. Since the wheel is used for navigation as well as volume control, one must leave the menu to adjust the volume. The Carbon can play MP3 and WMA audio files as well as Audible.com audiobook files.