The listing culture is a hybrid between gutenberg galaxis and software. Software was often distributed in the mainframe time as source code ( c ). each system had a different set of hardware, processor. c and co were the platform. You could compile it for your system. 

The listing culture brought source code to the magazines and could be published. first with basic and co for homecomputers, later with checksums, than basic with assembler inlines, than only shortcodes. 

of course by typing in you could learn how to code and solve problems.