oneAPI installation impact on currently integrated compilers in windows VS?

[dajum]

Is there a known process on how to install the 2021.1 classic compiler and still maintain the ability to use the 2020 version within Visual Studio? Or is it seamless?

[Steve_Lionel]

• How can I use multiple versions of the compiler in Microsoft Visual Studio*?

The article hasn't been updated in a while, but the fundamentals are the same.

[Devorah_H_Intel]

oneAPI installation will not remove your previously installed compilers from your system and from Visual Studio. It will only replace the integration component with the latest one in oneAPI.

[JohnNichols]

oneAPI has according to the literature the classic Fortran compiler built in - 

[Steve_Lionel]

Your old compiler will stay installed, but VS integration may not support compilers more than two or possibly three versions earlier. I know that the 19.1 compiler is still supported.