This thesis addresses the issues of porting software from one machine environment to another. Some general observations are made about the definition of Portability and the design and portability of programs written in high level programming languages, in particular Fortran. Two areas of portability are considered in detail: (i) Portability Criteria and Measures - The main criteria affecting the portability of Fortran applications are identified and possible measures of the effects of these criteria considered. A Portability Function is defined for obtaining a measure of the percentage portability of Fortran programs. (ii) Portability Assistant - The use of existing analysis tools to obtain measures of the criteria affecting the portability of Fortran programs is considered. A portability assistant is provided in the form of an Ingres Relational Database, which holds die data obtained from these measures, enables the portability function to be applied to the application and assists in the porting of the application. The methods of measuring the criteria affecting Fortran programs and the use of an Ingres database as a portability assistant is then applied to a particular example, the porting of NOMIS, a large manpower database
