Apple Power Macintosh 5400 series - Manual (Page 20)

Connecting a keyboard with a separate cable
1 Plug the mouse cable into the port on either side of the keyboard.
Most right-handed people prefer to use the mouse with their right hand; most
left-handed people prefer to use their left hand. Plug the mouse into the port
on the side you prefer.
The plug and the port are marked with the ◊ icon (symbol). Align the icons
before you insert the plug. (The positions of the port and icon on your
keyboard may be different from those pictured here.)
By the way: A port marked with the ◊ icon is called an Apple Desktop Bus
(ADB) port.
2 Plug the keyboard cable (both ends are the same) into the other port on the keyboard.
ADB icon
8 Chapter 1