As a teenage ham radio operator, I took the Motorola microprocessor course at Chapman college in 1978 because the teacher was my friend, N5BO. I learned how to code in 6800 machine language and, eventually also assembler. Fast forward to high school's PDP-11/45 and then afterwards, the PDP-11/44 at the Weisman Institute in Rehovot, Israel for the summer and Los Alamos National Laboratory's photochemistry division's Data General Iron.
The trick was that back then the state of the art of computer programming was so rudimentary that anybody could learn. On top of that, since computers were all designed by electrical engineering majors, all the documentation was written by and for people with such an education and I, having been a ham radio operator since age 13 was one of them, it was very comfortable sliding into programing.