USB full name of Universal Serial Bus,USB support hot-plug,plug and play is the advantage,so USB port has been the main port way of MP3.USB has two standard:USB 1.1 USB 2.0.

Transmission speed up to 1.5Mbps(b is bit),1MB/s=8Mbps,12 Mbps=1.5MB/s.USB2.0 is the update one from USB1.1,it’s transmission speed up to 480Mbps,is equal as 60MB/s,can meet various speed demands.The EHCI of USB2.0 is compatible with USB 1.1.