I now coldfusion 8 is old but can i install it on windows 10
Yikes! CF 8 is definitely not designed to run on Windows 10. And since Windows 10 is not a server platform, I doubt that Adobe has done any testing. That said, you can certainly get the essentials of CF to run on Windows 10. CF is very loosely coupled with the rest of the OS. During the install, you may be able to "trick" the installer into thinking it's on Windows 7 - there's a checkbox for that in the shortcut for every program. Likewise, you could actually just install it somewhere else, then copy the entire directory to your Windows 10 install! That's how disconnected it is from the rest of the OS.
There's a single Windows registry key that lets CF store client variables in the Windows registry. You don't really need this at all, and I would not recommend you store client variables in the Windows registry. But if you really want that registry key, you can go to the "manual uninstallation" instructions to see where it lives.
Finally, the one part where you're most likely to have a problem is with connecting CF to IIS. So, I'd recommend you not do this. If you're using this for development, you really don't need to connect CF to IIS at all.
Dave Watts, Eidolon LLC
Thank you Dave