Can I install with very small C drive?

I have an old PC I use for testing things. I want to install Win10 on it before installing it anywhere else. But this PC has an 80GB SSD C drive. Currently it has only 12GB free. I can free up maybe 6 or 7 more GB by removing a bunch of USER temp data (if I'm brave enough), but that is still way below the Win10 system requirements. I have 2 additional internal drives, 512GB each. (Seemed like a lot 5 years ago.) The D drive has over 400GB free. Is the Win10 installation smart enough to use space on the D drive, or am I going to have to replace my small SSD with something bigger?

Windows 10 will be installed to whatever drive you direct it and that will be the C: drive for Windows 10. Multiple operating systems on one computer will assign their own drive letters, quite independently what they are to other operating systems. Drive letter information is stored in the registry of each OS.

Ok. I need to get my head around that. User data (AppData, etc.), ProgData, etc. are currently on my small SSD. In Win10 with it's C drive on one of the HDDs are symbolic links going to allow them to stay there, or are they going to be copied to the Win10 C drive? Having the operating system on a slow HDD and user data on a fast SSD is kind of weird. (I don't want to even consider that they may be created on the Win10 C drive but not populated. The Win10 system would be pretty unusable then.)

I assume the Program Files that currently exist on both C and D drives would stay where they are. I installed most programs on the (current) D drive, but at least one program installed program files on both C and D, claiming that some of the files had to be on the C drive. And that's the only really important software I have on this PC. I assume this program is going to fail if the (logical) C and D drives are swapped. This doesn't sound like a good option.

I ended up replacing the 80GB SSD with a 256GB SSD.

pokeefe0001 said:

I ended up replacing the 80GB SSD with a 256GB SSD.

When my desktop was still on Win8.1 I have all that on a 914GB HHD for year, and then upgraded to Win 10, and all was fine, and it still has all the upgraded new and old /windows.old folder abd lots STUFF in my Downloads folder. It is permanently activated and my explorer says it still has 814gb FREE. That may give some of you some info about size. I will be deleting the /windows.old folder soon and changing to a 500GB Samsun SSD evo SATA III that I ordered yesterday.
mmore later.. all be safe.. Cliff M.