The file probably contains one or more null characters. By default, NoteTab treats the first null character it encounters as the end of the text. To change this behavior, you can set the Filter Binary Codes option which you will find on the Files tab in the Options dialog box. When this option is set, any null character NoteTab encounters when loading a file is converted to the substitute character (also defined in the Options dialog box). You will be able to load the full content of any file when this feature is enabled.
First, you need to select the
Go to View > Options > View
Then check Show Advanced Features
Then click on the Files option, check Filter Binary Codes and click OK.