Warning:Windows 11 24H2

Please be aware that (in the UK at least) automatic updates for Windows 11 now give you version 24H2.

Win32 applications that contain calculations that underflow will currently not recover unless underflows are masked.

This only applies to Win32 applications, not x64 and not .NET.

Win32 underflows can be masked by either:

1. calling mask_underflows@() or
2. setting the environment variable SALFENVAR=mask_underflows

This applies for all versions of salflibc.dll prior to FTN95 v9.10.

Can I ask what is the likely result of a program not recovering from underflow? Is seizing up a likely result?

Seizing up is exactly what happens if you take an underflow in Win32. FTN95 9.10 and above turn off underflow trapping to stop this.

You can expect the program to fail at runtime. It will terminate and display an error report.

The problem was caused by a change in the Windows operating system that affected Win32 FTN95 programs (not x64 and not .NET).

You should use a recent release of FTN95 or make the changes described above.

Just to be 100% clear, for Windows 11 and 32 bit programs

If I use an older version of SALFLIBC.DLL then it will be necessary to recompile with a call to mask_underflow@() (presumably added near the start of the program?)

On the other hand if I use the most recent version of SALFLIBC.DLL then it will NOT be necessary to recompile with an added call to mask_underflow@()

If I compile a 64 bit version then this is not an issue, regardless of the version of SALFLIBC.DLL

Thanks Louis

Louis

Your summary is correct.