I left HS in 1976, calculators were banned at most schools but it wasn't much of a problem because they were very expensive. My dad was an engineer and his company bought him a HP21C calculator for work. To use it I had to learn RPN from the manual. Dad recently found it in the back of a cupboard, he cleaned out the mess the corroded battery had made, got it working again, and gave it to me for Christmas, great conversation piece.
My first "real" computer with a true programming language was a second hand Apple IIe in the 80's, I learned Apple basic from manuals, the library, and magazines (Byte magazine and others published lots of example source code in those days). I think the internet has taken much of the leg work out self teaching all sorts of subjects, information has never been so easy to obtain.
My initial motivation for buying the Apple was that I had read about Conway' game of life in and old SciAm magazine at the library and was fascinated by it, spending hours and hours "playing" by hand on graph paper, it took me a week to figure out how to get the computer to do it. The guy I bought it from was floored when I showed him what I had done with it in the first week. A few years later he was amongst a handful of workmates at the factory who encouraged me into going to uni and taking up programing professionally. I swapped the factory job for a more flexible (and less profitable) taxi driving job and graduated in 1991, with 20/20 hindsight it's one of the best decisions I ever made. However the fact that I graduated at the perfect time to take advantage of the great IT gold rush of the 90's, was pure luck.
I think the hardest problem for most people (especially 20-somethings) is figuring out what they want to do for a living, I was in the same boat until I fully realized I could turn my strange hobby into an interesting and profitable career, being treated like a minor celebrity during the boom times of the 90's was an unexpected bonus.