Hello,
yes HD is 1TB and Debian partition is 300GB (not Mb).
Currently Windows starts directly without reporting other OSes present.
So should I use the installation disk in "rescue mode" and reinstall Grub to Debian's / partition (27.94 GiB dev/sda6)?
How to install os-prober?
I think I have to be able to boot Debian first to be able to install it later.
Right?
Francesco