This is a ROM from a mystery IEC compatible drive that identifies itself as a YIG-DOS drive.
At some point (when I get around to it) I'll take pictures of the innards and post them.
These graphic files, once printed out will provide a template for creation of a cardboard floppy insert useful when shipping drives as the 154x and 157x models (and others?) would suffer from head bang damage if not secured with the insert.