Using IDE 1.8.13, win10
Download then install any Python. I prefer 3.6 / 64 bit.
Associate CPP files with your favourite editor. Or, download then install the free Visual Studio.
Did that and managed to open an .ino file. Unsure exactly how to know .cpp file are associated with VS - if indeed that's what the instruction means.
Put the batch file somewhere on your PATH.
Did that. It's not in any way functional, for now it's just a placeholder.
Now, my understanding is I need to
a. put the code from original post #5 into arduino assembler.bat then
b. name that file in the python script(?) and finally
c. invoke C:\Python64\python ds.py from a command prompt.
Am I missing any steps?