Windows 10: question about registry entries when wiping hard drives

I recently wiped (reformatted) my system hard drive and installed a new OS on it (from win 7 to 10). I have multiple hard drives with a lot of my 3rd party programs (games, utilities, tools etc) installed on secondary drives. Originally, I had just assumed that I would have to reinstall most of those programs because their registry entries would have been wiped from the drive with the old OS... but everything seems to be working fine (so far) and I don't understand why. I realize some programs don't even bother with registries these days but things still seem to be running too smoothly (at least on the surface). I'm not familiar enough with how registry entries are added (both on the fly and via installations) to know whether I'm missing something, or maybe win 10 is just a lot more adept at these sorts of things?

:)

 

How to wipe a hard drive

modder I already used kill-disk. The deletion is done, I need to reinstall everything.

 

How to wipe a hard drive

Killdisk is a good hard drive eraser if you are still looking for suggestions.
http://www.killdisk.com/downloadfree.htm

 

How to wipe a hard drive

The best utility to use to wipe a hard drive is definitely DBAN. You can do an all-out wipe, or simply write all zeroes to the drive.

Darik’s Boot and Nuke – DBAN