More the 70s than 80s; our company wrote software in the mid 80s more or less the same as we (my company) still does; in the 80s-90s we just did ship a v1.0 a lot later than we do now, simply because in those times ages were basically impossible. Especially software on cardridges made it so you had to ship with 'no bugs'. But no blueprints; we just started on an idea we had and worked until it was good enough to ship.
> But no blueprints; we just started on an idea we had and worked until it was good enough to ship.
Yes, exactly. A lot of UNIX and other very good software for computers back then came about this way too. No or minimal blueprints and a lot of iterative implementation & testing and reacting to what you see.
It's hard convincing people today that agile methods have been in use long before sprints were a thing.
