Didas 1.1.1 is available as a free download on our software library. This free software was originally created by Agricultural Research Organization - The Volcani Center. Didas relates to Education Tools.
From the developer:
DIDAS is a software package aimed at assisting irrigators in the design of drip irrigation systems and in irrigation scheduling. The program simulates drip irrigation of various annual crops and trees at various soils and evaporation conditions. It evaluates the plant water use efficiency, but not plant growth and yields.
You may want to check out more software, such as Trachtenberg Speed Math, MathMatic or roboBASIC, which might be similar to Didas.