In this 1970 paper, presented at the Western Conference of the Institute of Electrical and Electronics Engineers (IEEE) in 1970, author Winston Royce sets forth the development steps that came to be known as Waterfall.  Unfortunately, it was a "straw man" version of Waterfall in his Figure 2, a version without iteration and feedback loops, that came to be popularized as "Waterfall". Royce himself was quite emphatic in his graphical portrayal of "modifie…