hey guys i have a 840c desk jet printer. and it has a port for the pc to connect to it, and also it has another port above it.

my case is that i want to use that printer for my mac g4.
i looked behind the mac and the usb port is thin and slender. but the port behind the printer seems like to be a usb port but it looks nothing like the usb port behind the mac. its more of a box shape. with one end shaped like rough point (triangle).

can someone tell me what that port is? could my 840 deskjet be used with my mac?