Comment Teach Yourself Cobol + Filetab + RPG + APL (Score 1) 623
As an ancient person, I learnt COBOL from a book but I didn't have a computer. Then when I got near a mainframe, I taught myself filetab: https://en.wikipedia.org/wiki/Filetab and later stll I used RPG2: https://en.wikipedia.org/wiki/IBM_RPG, later still Basic on a mainframe via a TTY33 [of course] and also the ineffable APL: https://en.wikipedia.org/wiki/APL_(programming_language) which prepared me for my career in Perl. If you think Perl is unreadable, try APL, but get off my lawn first.