I did that, too. Maybe age 6/7. Didn't get a computer myself until I was maybe 11. I learned from library books and ported and modified the tutorial programs for a class mates computer. Pen and paper, what else was there? It was fun and the logic of it was really interesting, but it didn't go very far with the information and equipment of the day (or following decades). What other people found weird was mostly that I wasn't interested in games which is apparently what home computers were for.

I often wonder what life would have been like if I had got some processor architecture manuals and microcontrollers early on. I've only specialized in embedded systems much later in life and spent my earlier life doing other, somewhat adjacent, things.