Mystery 1974 vintage TI chip: N286M26
I know this request is getting a bit old and on the chance you have not found your data yet, I have a couple of resources for you to check out.
First is the bitsavers TI section on archive.org.  They have a number of vintage data books in searchable PDF. I used to have several of these books in cellulose but now rely mainly on these PDF when working with vintage devices
Second, you can try going directly to the TI sub folder on http://www.bitsavers.org/pdf/
Good luck.