Preview of D64 files


I installed Dirmaster ( This is a program that allows viewing/editing of various Commodore 64 emulator files such as D64 (disk images) and T64 (tape images) files. It also includes a preview handler for these files. Previewing works in Windows Explorer but I can't seem to get it to work in Directory Opus.

Is this expected behaviour or do I need to change a setting somewhere?

It's because they haven't registered their preview handler properly.

If you add this to your registry, it works:

Under: HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\PreviewHandlers
Name: {3F4845D4-7173-4D6B-8E6B-1B0B2DE04B7E}
Type: String (REG_SZ)
Value: DirMaster (or whatever you want its name to appear as)

I've made a change for the next version so this will work automatically, too, if you don't want to edit the registry and would rather wait for that. A new beta should be released early this week.

1 Like


Thank you very much for the prompt reply. Your solution works perfectly, I can 't wait for for the next beta. I also forwarded this to the programmers of Dirmaster, hoping this helps them too.

1 Like