Use this command to view a file in Hex format.  This mode is generally used for binary (non-text) files, although text files can also be viewed in Hex mode.

 

Vertical Hex mode can be enabled by selecting Text+Vertical Hex from the View menu (or by pressing Alt+J). This is a cross between Text and Hex modes.

 

Click here for further details on viewing files in hex (and vertical hex) mode.