Abstract: A standardized test environment assists identifying problematic instances of instructions in computer programs that produce erroneous results. A standardized production environment takes corrective action for selected instructions by intercepting instruction processing during instruction fetch, instruction decode or instruction execution and modifying one or more values such that the instructions achieve correct results. In one embodiment of a test environment, a computer system collects diagnostic information for designated instructions such as subtraction operations that produce negative results. In one embodiment of a production environment, a computer system intercepts instruction processing for instructions at specified locations in a program and takes corrective action according to information obtained from a table of control information.

Abstract: A standardized test environment assists identifying problematic instances of instructions in computer programs that produce erroneous results caused by dates having years expressed in a truncated form. A standardized production environment takes corrective action for specified instances of instructions by modifying one or more values such that the instructions achieve correct results. In one embodiment of a test environment, a computer system collects diagnostic information for instances of subtraction operations that produce negative results. In one embodiment of a production environment, a computer system intercepts execution of a computer program at specified locations and takes corrective action according to information obtained from a table of control information.