 Note that EIA/TIA 561 combines DSR and RI, and the Yost standard combines DSR and DCD.Some serial ports on motherboards or add-in cards provide jumpers that select whether pin 1 of the DE-9 connector connects to DCD or a power supply voltage, and whether pin 9 of the DE-9 connector connects to RI or a power supply voltage.The power supply voltage can be +5V, +12V, +9V, or ground.