If the DAT file you're trying to open is text, you can convert the file into text in the Microsoft Excel program by first saving it as a CSV file.

To import data from a text file into Microsoft Excel, follow this step-by-step guide: First, create a blank spreadsheet in Microsoft Excel and ensure you have the .txt file on your PC.

How to Automatically Convert an Excel File to Text Using Visual Basic. Microsoft's ubiquitous spreadsheet application, Excel, is a useful tool for small and large businesses alike. However, the ...