The DFD-1 (Document Finishing Device) interface is a simple low level parallel interface. Basic finisher control and status feedback is achieved with 8 input lines (only 3 used) and 8 output lines (only 3 used).
In DFD-1 only 6 lines of the available 16 are used. As such, the interface does not fully utilise the possibilities the hardware offers.
However, the DFD-1 interface has a steady basis in the field. It will be supported despite all its disadvantages.
For the complete interface specification, see DFD-1.