The parallel port interconnect is considered a legacy port since it is being replaced by the USB / Firewire interconnect. Parallel port interconnects were commonly used by printers. Maximum data rate is 50 to 150 kb/s.
The PS/2 interconnect is used to connect keyboards and mouse interfaces. Like parallel and serial ports, the PS/2 interconnect is slowly being replaced with USB and Firewire.
BNC is a versatile interconnect that can be used to carry video, audio, and data signals. Data cables using BNC interconnects are found mostly in professional data acquisition hardware. A BNC interconnect is almost always found using a coax cable, which means it can only pass a single channel. The signal can be digital or analog.