General Software Model

Windchill Risk and Reliability Desktop Help > Windchill Prediction > Part Parameters Required for Predictions > General Software Model

The failure rate of a software component can be calculated using the software reliability equation from The Rome Laboratory Reliability Engineer's Toolkit, April 1993 issue, page 124-125. This equation was originally extracted from Rome Laboratory Technical Report RL-TR-92-15, Reliability Techniques For Combined Hardware and Software Systems.

The following table describes the part parameters required when Software/RADC Toolkit Software is selected as the part category/subcategory combination.

Parameter	Type	Description
Processor Speed	Real	The host processor speed in MIPS (Millions of Instructions Per Second).
Fault Exposure Ratio	Real	The fault exposure ratio is a function of program data dependency and structure. The default is 4.2e-7.
Fault Density	Real	The estimated number of faults in the initial program per every 1000 lines of source code. The default is 6 faults per 1000 lines of source code.
Lines of Code	Integer	The total number of lines of source code.
Programming Language	Choice List	The language that the source code is written in. This is used to determine that number of object instructions. Higher level languages have more object instructions per line of source code than lower level languages.
Fault Reduction Factor	Real	The fault reduction factor. The default is 0.955.
CPU Seconds/Hour	Integer	The number of seconds that the CPU operates per clock hour.
Time (Hours)	Real	The CPU execution time in hours. When the calculation runs, failures per CPU second are converted into whatever failure unit time is specified under General in the System file properties. The default is failures per million hours. For more information, see General System File Properties.