Is it possible to compile modules written in Fortran 90 with a main program that is written in Fortran 77?
If you add modules to F77 code, it’s no longer F77. Hence, a true F77 compiler, such as pgf77, would not be able to compile this file. Though, using a F90/F2003 compiler, such as pgfortran, will be able to compile the code.
Since F77 is a subset of F90, all F90/F2003 compilers should be able compile F77 code with the exception of a few deprecated F77 features.
Hope this helps,
Thank you Mat for your reply,