Files with the extension HEX contain data that are saved in a hexadecimal format. Hexadecimal format is a variant of binary format that encodes numbers using a base 16 number system rather than the base 2 system that computer systems use. You can create a HEX file using a simple text editing program or you can use a HEX editing tool such as Ohio State University's free HexEdit tool.
Create HEX in Notepad
Click the "Start" button and choose "Programs," "Accessories," then "Notepad." Doing so will open the Windows notepad text-editing program.
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Type in your code in hexadecimal format. Hexadecimal represents numbers in base 16 format, with values ranging from the digits 0 through 9 to the characters A, B, C, D, E and F, which respectively represent the numbers 10, 11, 12, 13, 14 and 15.
Click "File," then "Save As" to save the text file to your hard drive. Choose the file extension HEX instead of the typical Notepad extension TXT. Doing so will allow any program that reads data from HEX files to read your hexadecimal code.
Create HEX in HexEdit
Download Ohio State University's free HexEdit program (see Resources). HexEdit allows you to create and modify HEX files while simultaneously viewing the ASCII equivalent of your code in another program window.
Double-click the downloaded HexEdit EXE file to run the program.
Click "File," then "New" to create a new HEX file.
Type in your code into the program in either hexadecimal format or ASCII format. Press the tab button to shift between the middle window, which shows values in hexadecimal format, and the right window, which shows values in ASCII format.
Click "File," then "Save" to save your file in HEX format.