Herein are some notes on installing the Intel Fortran compiler on Windows 11

Some Fortran compiler history:
 - We used the DEC 32-bit compiler until 2018, when it would not install on 64-bit Windows 10
 - We used the Lahey 32-bit compiler until July 2025, when my computer it was installed upon failed
 - DEC and Lahey are no longer available, and, neither were ever offered in 64-bit versions
 - One benefit of 32-bit was the ability to run on older systems, of which we suspect very few remain
 - We move to the Intel 64-bit version as suggested by Nic Spycher (aside, their 32-bit version was deprecated in Oct 2024)
 ____________________________________

                SUMMARY

- The Intel Fortran compiler requires a specific version of MS Visual Studio, that must be installed first
- After installing Visual Studio, then there are two Fortran compiler options available:
      - As a standalone compiler
      - As part of the oneAPI toolkit
- We tested installation of the oneAPI option. The standalone option is untested
- Additional tools supplied with oneAPI remain unexplored for now

THE COMMAND LINE INTERFACE FOR THE ONEAPI OPTION APPEARS TO WORK AS ADVERTISED, woo hoo

Post install notes:
When starting the Windows Terminal oneAPI command line interface,
it *appears* that each module is verified to be the latest (check this)
____________________________________

DOWNLOADS FROM MS AND INTEL ARE UPDATED OFTEN, so it's best to get the latest versions at the time of installation
____________________________________

The Intel Fortran compiler (either option, see below) needs a specific compatible version of MS Visual studio
Compatible versions as of 9/10/2025 MS Visual Studio are:
VS 2022 17.14.14
VS 2019 16.11.51

At the time of download, three options are offered: 1) Community, 2) Professional, AND 3) Enterprise
Get 1) Community, as it is the only free one (the others have a 30 day trial)
https://visualstudio.microsoft.com/downloads/

I ended up with: Microsoft Visual Studio Community 2022 (64-bit) - Current Version 17.14.14

During installation or modifying after, it's necessary to install the "Desktop development with C++" component
  1)  Open the Visual Studio Installer (See Windows Start or Windows Desktop)
  2)  For the installed version of Microsoft Visual Studio*, select Modify
  3)  Under the Workloads view, select the checkbox to install the Desktop development with C++
  4)  Select Modify
  5)  Continue with the installation

____________________________________
Below, needing only one of the two, we went with second one, the Intel® oneAPI HPC Toolkit
https://www.intel.com/content/www/us/en/docs/fortran-compiler/get-started-guide/2025-1/get-started-on-windows.html

INTEL FORTRAN
Standalone
https://www.intel.com/content/www/us/en/developer/tools/oneapi/fortran-compiler-download.html
Intel® Fortran Compiler: Offline
Size 533.24 MB
Version 2025.2.1
Date August 14, 2025
intel-fortran-compiler-2025.2.1.11_offline.exe

***OR***

As part of Intel HPC Toolkit
https://www.intel.com/content/www/us/en/developer/tools/oneapi/hpc-toolkit-download.html
Intel®  oneAPI HPC Toolkit
Size    2874.81 MB
Version 2025.2.1
Date    August 18, 2025
intel-oneapi-hpc-toolkit-2025.2.1.46_offline.exe

During installer configuration one might think that the computer has frozen. Give it at least an hour.
____________________________________

Once installed, in the start menu, find the folder "Intel oneAPI 2025" and inside that,
   program "Intel oneAPI command prompt for Intel 64 for Visual Studio 2022"
   I made a shortcut and put it on the desktop

The actual command to put is "ifx", e.g.
"ifx chim-xpt.f" to get chim-xpt-exe

and away we go...
____________________________________



PATH=C:\Program Files (x86)\Intel\oneAPI\vtune\2025.4\bin64;
C:\Program Files (x86)\Intel\oneAPI\tbb\latest\env\..\bin\\;
C:\Program Files (x86)\Intel\oneAPI\pti\latest\env\..\bin;
C:\Program Files (x86)\Intel\oneAPI\ocloc\latest\bin;
C:\Program Files (x86)\Intel\oneAPI\mpi\latest\env\\..\opt\mpi\libfabric\bin;
C:\Program Files (x86)\Intel\oneAPI\mpi\latest\env\\..\bin;
C:\Program Files (x86)\Intel\oneAPI\mkl\latest\bin;
C:\Program Files (x86)\Intel\oneAPI\ippcp\latest\bin;
C:\Program Files (x86)\Intel\oneAPI\ipp\latest\bin;
C:\Program Files (x86)\Intel\oneAPI\dpcpp-ct\latest\env\..\bin;
C:\Program Files (x86)\Intel\oneAPI\dnnl\latest\env\..\bin;
C:\Program Files (x86)\Intel\oneAPI\dev-utilities\latest\bin;
C:\Program Files (x86)\Intel\oneAPI\debugger\latest\env\\..\opt\debugger\bin;
C:\Program Files (x86)\Intel\oneAPI\dal\latest\bin;
C:\Program Files (x86)\Intel\oneAPI\compiler\latest\lib\ocloc;
C:\Program Files (x86)\Intel\oneAPI\compiler\latest\bin;
C:\Program Files (x86)\Intel\oneAPI\advisor\2025.2\bin64;
C:\Program Files\Microsoft Visual Studio\2022\Community\VC\Tools\MSVC\14.44.35207\bin\HostX64\x64;
C:\Program Files\Microsoft Visual Studio\2022\Community\Common7\IDE\VC\VCPackages;
C:\Program Files\Microsoft Visual Studio\2022\Community\Common7\IDE\CommonExtensions\Microsoft\TestWindow;
C:\Program Files\Microsoft Visual Studio\2022\Community\Common7\IDE\CommonExtensions\Microsoft\TeamFoundation\Team Explorer;
C:\Program Files\Microsoft Visual Studio\2022\Community\MSBuild\Current\bin\Roslyn;
C:\Program Files\Microsoft Visual Studio\2022\Community\Team Tools\DiagnosticsHub\Collector;
C:\Program Files (x86)\Windows Kits\10\bin\10.0.26100.0\\x64;
C:\Program Files (x86)\Windows Kits\10\bin\\x64;
C:\Program Files\Microsoft Visual Studio\2022\Community\\MSBuild\Current\Bin\amd64;
C:\Windows\Microsoft.NET\Framework64\v4.0.30319;
C:\Program Files\Microsoft Visual Studio\2022\Community\Common7\IDE\;
C:\Program Files\Microsoft Visual Studio\2022\Community\Common7\Tools\;
C:\Program Files (x86)\Common Files\Intel\Shared Files\cpp\bin\Intel64;
C:\WINDOWS\system32;
C:\WINDOWS;
C:\WINDOWS\System32\Wbem;
C:\WINDOWS\System32\WindowsPowerShell\v1.0\;
C:\WINDOWS\System32\OpenSSH\;
C:\Program Files\dotnet\;
C:\Program Files (x86)\Windows Kits\10\Windows Performance Toolkit\;
C:\Users\palandri\AppData\Local\Microsoft\WindowsApps;
D:\01_Sys\batch;
D:\01_Sys\WCD\bin\;
;
C:\Program Files\Microsoft Visual Studio\2022\Community\Common7\IDE\CommonExtensions\Microsoft\CMake\CMake\bin;
C:\Program Files\Microsoft Visual Studio\2022\Community\Common7\IDE\CommonExtensions\Microsoft\CMake\Ninja;
C:\Program Files\Microsoft Visual Studio\2022\Community\Common7\IDE\VC\Linux\bin\ConnectionManagerExe;
C:\Program Files\Microsoft Visual Studio\2022\Community\VC\vcpkg;
C:\Program Files (x86)\Intel\oneAPI\umf\latest\bin;
C:\Program Files (x86)\Intel\oneAPI\tcm\latest\bin