Oh, this is fun. The Computer History Museum got permission to publish the
Apple II DOS Source code as part of their library to document the
history of classic software. They have text files for part of it, but some of
the code is provided as PDFs from scanned sheets of the green-white printer
paper—complete with feeder holes. I loved tearing those things off.
This brings back so many memories of hacking the Apple IIgs as a teen.
I learned how to do assembly and C programming by picking apart whatever I
could find in a few dozen magazines at the local library, all while dreaming
about the day when we could find all this information instantaneously in
“cyberspace”. Good times.