Most of the detail stress analysis of the 747 was done with slide rules and hand cranked calculators. Electronic calculators (with glowing filaments) were just coming into use and a little later we had a few HP and TI desk top calculators like the HP 9100 (
https://en.wikipedia.org/wiki/Hewlett-Packard_9100A). It was generally quicker and easier to use your own slide rule than fight for a calculator.
We had access to a CDC 6600 "supercomputer" (
https://en.wikipedia.org/wiki/CDC_6600) for (early versions of) finite element analysis of interaction between main structural elements The CDC 6600 had to be booked overnight and was too slow in that it took 24 hours to discovered you'd stuffed up the input data! Or someone dropped the deck of cards!
BTW Sutter wrote in his 747 book that there were no fax machines; whereas I clearly remember liaising with Northrop using a Xerox device which was like a photo copier with scan and print functions hundreds of miles apart.