TOS file: How can I open a .TOS file?
The table below provides useful information about the .tos file extension. It answers questions such as:
- What is the .tos file?
- What program do I need to open a .tos file?
- How can the .tos file be opened, edited or printed?
- How can I convert .tos files to another format?
We hope you find this page helpful and a valuable resource.
✅ Atari ST TOS Executable

The TOS file is a Atari TOS Executable. TOS is the operating system of the Atari ST range of computers. TOS file is a program that didn't use GEM (Graphical Environment Manager).
✅ The Only Sheet Settings Data

The TOS file is a The Only Sheet Settings Data. The Only Sheet is a character sheet workbook that's powered by Excel.
⚠ Be careful with .tos files.
It's important to know that the .tos file extension can be used by various programs, not just the ones you expect. This includes potentially harmful software or malware that might create .tos files. Be cautious when dealing with .tos files from unknown sources.
🚫 The .tos file extension is often given incorrectly!
According to the searches on our site, these misspellings were the most common in the past year:
Is it possible that the filename extension is misspelled?
We found the following similar file extensions in our database:
🔴 Can't open a .tos file?
When you double-click a file to open it, Windows examines the filename extension. If Windows recognizes the filename extension, it opens the file in the program that is associated with that filename extension. When Windows does not recognize a filename extension, you receive the following message:
Select an app to open this .tos file
It means that the operating system does not have a default app associated with the .tos file type. To resolve this issue and open the file, you can take the following steps:
- Right-click on the .tos file. A context menu will appear.
- From the context menu, select Open with. Windows will display a list of recommended apps.
- If the desired app is listed, select it from the provided options.
- If you cannot find the appropriate app, you may need to install software that supports the specific file type.
If you don't know how to change the default app for the .tos file, check the FAQ.
🔴 Can I change the extension of files?
Changing the filename extension of a file is not a good idea. The extension of a file serves as a hint to the operating system and various software programs about the type of data contained within the file. When you alter a file's extension, you essentially modify how software applications interpret and handle that file. Every file has a specific format, also known as its file type or file format. The problem is, changing the file extension does not change the file format.
If you have helpful information about the .tos file extension, write to us.