1.  Technical Field
The present invention relates to a data processing apparatus and a data processing method, and more specifically, to a data processing apparatus which identifies a device coupled therewith and a data processing method. 
2.  Related Art
As an ordinary data processing apparatus of this kind, a cable identifying device to be coupled with cables for distribution in order in a case where a plurality of boosters having different values of resistors for identification is installed which checks booster numbers has been proposed, e.g., as disclosed in JP-A-2004-112729.  As for this apparatus, if a cable for distribution is coupled with a measurement terminal of the cable identifying device, a resistor for identification of a booster coupled with the cable for distribution is connected to a reference resistor for measurement of the cable identifying device in series, and a voltage of a power supply unit is divided and provided to an A/D converter.  The apparatus identifies the booster by checking digital data into which the divided voltage is converted by the A/D converter. 
Incidentally, the apparatus described above identifies a booster (coupled device) having a different value of the resistor for identification.  In some cases, e.g., it is desirable to distinguish a coupled device having a resistor from a coupled device having no resistor.  A method for identifying a coupled device more exactly in such a case has been desired.