Is this the realy cd of pc-os od?

It might be, but there are no real identifying features here.

SOLUTION:
Drag the README.diskdefines file from the disc onto the desktop and rename it README.diskdefines.txt (add .txt to the end of the file name). Windows will ask you if you really meant to do that and warn you about how naughty you are being, but just change it anyway.
Double click the file and it should open in Notepad so you can read it.
If it's PC-OS then the first line of this file will read something like this:

#define DISKNAME PC/OS Open64 Workstation

What ever it says - that's what it is OK.