While not new, since the concept was already described by Christopher Alexander in its architectural theories, it only gathered some traction in programming due to the publication of Design Patterns: Elements of Reusable Object-Oriented Software book in October 1994 by Erich Gamma, Richard Helm, Ralph Johnson and John Vlissides, known as the Gang of Four (GoF), that identifies and describes 23 classic software design patterns.
Use a calculator to calculate the stair riser length or the number of steps you'll need. Divide the height from the first floor to the top of the second floor by a predetermined height of your choice for the riser. The typical height of a riser is 6 or 7 inches (15 to 17.5 cm).
Spiral staircases fall under totally different code requirements. The minimum width of a spiral staircase is 26 inches, 10 inches less than a typical or winder staircase. Spiral stairs have no minimum tread depth at the narrow end and a minimum of 7-1/2 inches of tread depth at a point 12 inches from the inside edge.