An in3 file extension is related to the Harvard Graphics and used for its input device drivers.
IN3 file extension - Harvard Graphics input device driver
What is in3 file? How to open in3 files?
File type specification:
The in3 file extension is associated with the Harvard Graphics version 3.0., a graphics and presentation program for Microsoft Windows and MS-DOS systems.
The in3 file contains input device driver.
This in3 file type entry was marked as obsolete and no longer supported file format.
This type of file is no longer actively used and is most likely obsolete. This is typically the case for system files in old operating systems, file types from long discontinued software, or previous versions of certain file types (like documents, projects etc.) that were replaced in higher versions of their original programs.