What interface cables are compatible with the HL-3450CN, and are they included in the box?

The interface cable is not a standard accessory and must be purchased separately. The printer supports Parallel, USB, or Network interfaces, and you should purchase the appropriate cable for the interface you intend to use. Note that most existing parallel cables support bi-directional communication, but some might have an incompatible pin assignment or may not be IEEE 1284 compliant. (Page 1)