The 1965 calendar uses illustrations instead of photos. The illustrations exemplified various technologies and processes at Tektronix. The calendar included a tear-away bottom portion that could be tri-folded and used for a handy memo-minder (the calendar is missing some of the tear-away bottom portions).
Note that on September 25th there is a hand written note for "moon bounce", another mystery.
Click on the image to view the PDF.