You can specify the amount of free space of a mounted directory with the -freesize parameter to the mount command:

https://www.dosbox.com/wiki/MOUNT

okay thanks - i tried that now with a few variations of size - 200, 500, 1024 - all the same error, i dont know what the games install's problem is -- i am assuming the freesize is measured in megs?

I would guess so. A simple "dir" will tell you for sure. Can you post a video or pictures of the installation? Do you install from floppy images? Or did you copy the installation files to the c drive prior?

It's probably something else going wrong with copying files and the installer incorrectly assumes the problem is a lack of free space.

DOSBox's internal copy command doesn't handle wildcards very well so you might want to try installing under freedos or similar.

i was loading a cdrom drive and going from the install on that - the cd i have is a "CD Power" from 1997 it contains Their FInest Hour with all the extra missions.

i have however found a solution - in that if i just copy the files over to a folder through windows copy paste and just run the game exe, then the game runs perfectly, so i guess i dont need to worry about the install error - but its a shame as i do enjoy the nostalgia of doing a dos install when i can 😀

I owned a 40meg HD in my 286 back in 1990 so may want to try smaller than 200mb.