Good morning , we have a software developed with Visual Fortran 6.6.a that run on windows xp and 7 machines. I want to know what there would be in the switch to a new compiler version and recommended limits and values . What compiler version do you recommend ? Many thanks.
The Fortran language has undergone a good many revisions since Visual Fortran 6.6 and the current Intel Fortran compiler supports a lot of the new features. There is no need to adapt your programs to the latest version, but it may be that your code relies on non-standard features of that now rather old compiler. If your programs do not rely on any non-standard features, then there is a good chance that they can be compiled and run without a problem, as the Fortran standards do not lightly introduce incompatibilities with previous versions, for instance by deprecating certain features. Even then the compilers tend to keep support for such features.
That said, you should probably simply move to the latest version. Many compilers - including the Intel Fortran compiler - offer a switch to warn about non-standard items in the source code, so that it ought to be easy to find and correct them.
Without more concrete information, it is hard to give more specific advice.
https://software.intel.com/en-us/articles/migrating-from-compaq-visual-fortran has a lot of useful information for you.
Intel Parallel Studio XE 2016 for Fortran Windows is the recommended product. Most Compaq Visual Fortran applications simply need a rebuild with no source changes.