Please reply to the mailing list, not only to me. Just because I reply to you on the list doesn't mean I want have a private conversation about your questions I tried to give you exactly the info you want, but the URL was incorrect. The correct URL is https://gcc.gnu.org/wiki/InstallingGCC On Wed, 28 Jul 2021, 09:32 Chang M. Kang via Gcc-help, <gcc-help@xxxxxxxxxxx> wrote: > Dear Sir, > > I am working on MCNP6 Monte Carlo Transport Code, which can be compiled > by using gfortran Version 4.8.5 through 6.4.0. > > - I located and downloaded a gcc 4.8.5 package from a mirror site. > > - I installed Cygwin using setup-x86_64.exe on Window 10 computer. This > Cygwin includes cygwin-devel 3.2.0 and gcc-fortran 9.3.0. > > Please let me know how to build a gcc in Cygwin with gfortran > 4.8.5 replacing gfortran 9.3.0. > > With best regards, > > CM Kang >