Document processing apparatus having fauet detection capabilities

In a document processing apparatus having:

• a plurality of kinds of input resources for inputting data;
• data processing means for processing data input through said input resources to correct, edit and/or to store the processed data in a storing means;
• a plurality of kinds of output resources which are operable for outputting data by way of a display, a printer or a sound generation, in accordance with the processed data by said data processing means;
• and
• control means for controlling said plurality of kinds of input and output resources and said data processing means to have a predetermined relationship to each other to enable a plurality of predetermined task modes;
• the improvement which comprises:
• diagnostic means for testing and determining whether or not each of said plurality of kinds of input and output resources is available;
• detecting means for detecting, when said diagnostic means determines that one of said plurality of kinds of input and output resources is unavailable, whether or not any one of said plurality of kinds of input and output resources can substantially respond in an acceptable mode for said one resource which is unavailable;
• and
• said control means, when said detecting means detects that the substitute source may respond in place of the unavailable resource, for selectively setting the task mode with the use of said substitute source to permit the document processing operation.