assmebly (calculator RPN)
https://dere.github.io/2017-02-12/beginners-assembly-part1/
webassembly
https://sourceware.org/ml/binutils/2017-03/msg00044.html
https://hacks.mozilla.org/2017/02/a-cartoon-intro-to-webassembly/
webassembly explorer
https://mbebenita.github.io/WasmExplorer/
free books
https://github.com/vhf/free-programming-books/blob/master/free-programming-books.md
https://john.cs.olemiss.edu/~hcc/csci658/notes/Free_Prog_Lang_Textbooks.html