DAP, the original name for "iPods" as most people call everything anymore. Digital Audio Players... They didn't do anything more then that folks! These are my 2 old Rio units. The first is a Rio Cali 256MB with a SD slot. It uses a single AAA battery. The second is a Rio 500, which is the first one that had USB! It also uses a plain off the shelf battery, AA in this case. It has 64MB of memory and a Smart Media slot for a total of 192MB! Wow I bet I will NEVER have that much music!