Patent ID: 7477247

Claim:
In a computing system supporting dual monitors, a method for responding to a change in the connection status of a secondary generally conventional analog monitor associated with the computing system, the method comprising the steps of: (a) monitoring a state of a signal at an output port of a video display adaptor, the signal being provided only during a blanking interval of a monitor output signal that is applied to the output port to drive the secondary analog monitor, wherein the signal is provided by a negative current source that is connected between the output port and ground only during the blanking interval; (b) detecting a change in state of the signal that occurs in response to one of: (i) a secondary analog monitor being connected to the output port, an input impedance of said secondary analog monitor causing the state of the signal to change in a first predefined manner when the input impedance of the secondary analog monitor is coupled to the output port; and (ii) the secondary analog monitor being disconnected from the output port, a removal of the input impedance of said secondary analog monitor causing the state of the signal to change in a second predefined manner as a result of the input impedance of the secondary analog monitor no longer being coupled to the output port; and (c) providing an indication of any change in the state of the signal to the computing system; and (d) in response to an indication of the secondary analog monitor being connected, enabling the display of an application or desktop on the secondary analog monitor in addition to a primary monitor, and in response to an indication of the secondary analog monitor being disconnected, disabling the display of any portion of the application or the desktop on the secondary analog monitor so that the application or desktop is displayed on the primary monitor.