Royce starts with a simplistic model, later named "Waterfall".
Royce first says that any software, no matter how small, requires two steps.
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I want to highlight the attractive curved arrow that points down and to the right. That’s a natural direction for a native English speaker because analysis precedes coding. Since we write left-to-right and top-to-bottom, we’re inclined to think of time as flowing in those directions.
Royce says that this process only suffices for small, in-house projects. When you build serious software, you need more phases to do the kinds of work that reduces risk.
He proposed Royce70's Seven Phases.
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