Chapter 11 Porting to HP Fortran 90

The goal of portability is to make it possible to compile and execute a program on different vendors' platforms, regardless of the platform on which it was written. A portable Fortran 90 program contains no language elements except those mandated by the Standard and adheres to generally accepted coding practices.

In practice, however, programming is rarely so simple. Many Fortran programs have a long history and were originally coded at a time when portability was not a concern because many programs were written to execute on one platform only. Older Fortran programs—so-called dusty-deck programs—are likely to have passed through different dialects of Fortran, picking up features from each, even after those features have become outmoded. Porting such a program may sometimes be as simple as identifying and removing the nonportable features. But more often than not, it involves finding ways to implement the functionality of the nonportable features.

To make the task of porting easier, HP Fortran 90 includes the following features:

The following sections describe these features.

	NOTE: For information about migrating HP FORTRAN 77 programs to HP Fortran 90, refer to Chapter 10 “Migrating to HP Fortran 90”.