[pjmlp]

Thunks were used to execute 32 applications in 16 bit mode via Win32s, and were also the way you would prepare callbacks to be exposed to Windows APIs.

[solarengineer]

I was about to add a reference to the win32s thunking, and then chanced upon this [0] MSDN article that talks about supporting 32 bit I/O in 64 bit drivers. [0] https://msdn.microsoft.com/en-us/library/windows/hardware/ff...