The Power Mac G4 computer has two external Universal Serial Bus (USB) ports that are used for connecting the keyboard and mouse as well as additional I/O devices such as printers, scanners, and low-speed storage devices.
The USB ports are connected to separate USB root hubs, allowing both USB ports to support 12 Mbps devices at the same time with no degradation of their performance.
For more information about USB on Macintosh computers, please refer to Apple Computer's Mac OS USB DDK API Reference and the other sources listed in About This Note.