Computer video output testing

Abstract

A system is described for testing the video output of a computer of the type in which a video output connector is provided with a data channel, such as a DDC channel, permitting data to be transmitted from a monitor connected to the video output connector to the computer. The system comprises test apparatus having a connector for connection to the video output connector of a computer under test, the test apparatus comprising means to measure parameters of test video signals received through the connector and means to generate a result signal from the measured parameters for transmission to the computer under test over the data channel. Software executing on the computer under test to generate the test video signals and to receive and process the result signal received over the data channel.

1 . A system for testing the video output of a computer of the type in which a video output connector is provided with a data channel permitting data to be transmitted from a monitor connected to the video output connector to the computer, the system comprising: 
 test apparatus having a connector for connection to the video output connector of a computer under test, the test apparatus comprising means to measure parameters of test video signals received through the connector and means to generate a result signal from the measured parameters for transmission to the computer under test over the Display data channel; and    software for execution on the computer under test to generate the test video signals and to receive and process the result signal received over the data channel.    
     
     
         2 . A system as claimed in  claim 1  wherein the test apparatus is arranged to derive power for its operational components from the video output connector.  
     
     
         3 . A system as claimed in  claim 1  wherein the test apparatus has a video output connector and an operating mode in which signals from the connector are passed transparently to the video output connector.  
     
     
         4 . A system as claimed in  claim 3  wherein the test appratus comprises a switch for switching from a mode in which signals from the connector are passed transparently to the video output connector to a mode in which signals received from the connector are processed within the test apparatus, the switch being responsive to a signal received via the connector to switch between the modes.  
     
     
         5 . A system as claimed in  claim 4  wherein the signal is a predefined number of read commands being received by the test apparatus within a predefined time.  
     
     
         6 . A system as claimed in  claim 1  wherein at least some of the parameters measured are voltages.  
     
     
         7 . A system as claimed in  claim 1  wherein at least some of the parameters measured are frequencies.