[reaperducer]

how did a teenager in that time period possibly get that level of technical introduction to things at that level?

Commodore published very detailed documentation for its computers, including schematics. You could buy these in most large book stores.

There was also lots of information available through local user groups, BBSes, BBS networks, and online services like GEnie, Delphi, The Source, and CompuServe.

Many local computer stores had regular meetings of their customers where people would exchange programs and information.