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What is a CSO File?

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Question: What is a CSO File?

Did you find a CSO file on your computer and wonder what program should open it? Maybe someone emailed you a CSO file but you're not sure how to use it. Perhaps you tried to open the CSO file but Windows told you that it could not open it.

Before you can open a CSO file (assuming it's even a file format that's intended to be viewed or edited), you'll need to determine what kind of file the .CSO file extension refers to.

Answer: A file with the CSO file extension is a CISO Compressed ISO Image file.

Other types of files may also use the CSO file extension. If you know of any additional file formats that use the .CSO extension, please let me know so I can update this information.

How To Open an CSO File:

The easiest way to open a CSO file is to double-click on it and let your PC decide which default application should open the file. If no program opens the CSO file then you probably don't have an application installed that can view and/or edit CSO files.

Warning: Take great care when opening executable file formats received via email or downloaded from websites you're not familiar with. See my List of Executable File Extensions for a listing of file extensions to avoid and why.

CSO files can be opened with the free PSP ISO Compressor, as well as the also free Format Factory which, by the way, can also convert back and forth between ISO and CSO.

If you know anything else about CSO files, please let me know so I can update this page.

Tip: Use Notepad or another text editor to open the CSO file. Many files are text-only files meaning no matter the file extension, a text editor may be able to properly display the file's contents. This isn't the case with CISO Compressed CSO files, but it's worth a try if you think the CSO file you have is of a different format.

If you find that an application on your PC does try to open the CSO file but it's the wrong application or if you would rather have another installed program open CSO files, see my How To Change the Default Program for a Specific File Extension guide for making that change in Windows.

How To Convert a CSO File:

There are two main ways to attempt to convert a CSO file to another file type:

The first option involving opening the CSO file in its native program is preferable because it's both easier and will probably result in a more accurate file conversion. Of course if you don't have a program that opens CSO files, a third-party file conversion tool (the second option) could be very useful.

Important: You cannot usually change a file extension (like the CSO file extension) to one that your computer recognizes and expect the newly renamed file to be usable. An actual file format conversion using one of the methods described above must take place in most cases.

Still Having Problems Opening or Using a CSO File?

See Get More Help for information about contacting me on social networks or via email, posting on tech support forums, and more. Let me know what kinds of problems you're having with opening or using the CSO file and I'll see what I can do to help.

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