frozen@mid80 is a program, for demonstrating a 1970s (upto the mid-1980) style of visual-programming, that was well-known in academic circles, but never finding popularity in programming, nor in the puzzle world.Listing a few (fix set of) macros -- with the flexibility of choosing how to link them.Good base for educating your intuition (for children, too) -- and with story examples, reflecting what a formal-net could represent.The page http://www.geocities.com/ferzenr/mid80.com.htm is telling about the software -- including the program manual. Requires: MSDOS (if state-saving wanted; if not, BIOS)