For anyone looking for the manual I have just uploaded a searchable PDF to Archive dot org. I can't post the link to the forum as I have too few posts (an anti-spam bot measure). If you go to 'archive dot org' and search for CompuNav you will find it. Perhaps someone who is able to post links can repost it to make it easier for other.
NOTE: I am still searching for the software cassette or a copy/wav file thereof. I'm interested in preserving things related to vintage pocket computers, especially ones sold for specific purposes. Thanks for any help.