Probably the earliest GraphicalProgrammingLanguage, designed in 1966 by WilliamSutherland (IvanSutherland's brother). It was heavily influenced by SketchPad, which itself was a domain-specific graphical ConstraintProgramming language (not general purpose, not TuringEquivalent). This is not all that widely known; Prograph is often called the first GraphicalProgrammingLanguage. Therefore here's some references:
* W. Sutherland, "On-line Graphical Specification of Computer Procedures," Ph.D. Thesis, M.I.T. Cambridge, Mass., 1966 http://theses.mit.edu/Dienst/UI/2.0/Describe/0018.mit.theses%2f1966-24?abstract=
* http://www.camazotz.com/vplpaper
* Taxonomies of Visual Programming and Program Visualization, http://www-2.cs.cmu.edu/~bam/papers/vltax2.pdf
* http://hopl.murdoch.edu.au/showlanguage.prx?exp=191&language=Sketchpad
* Visual Programming FAQ, http://burks.brighton.ac.uk/burks/pcinfo/progdocs/vprogfaq.htm
* A Man-Machine Graphical Communication System, http://citeseer.ist.psu.edu/context/1346665/0

----
CategoryProgrammingLanguage