Program written in 1960 still being run. (Score 1)

In 1960, I wrote a program that computed fan capacity tables for use by HVAC sales engineers for American Air Filter. The original use was to run this program over a wide range of inputs and print the tables in a hard cover book for HVAC enginners to use when designing the heating and air conditioning system for a large building. The last time I checked, this program is still being run, only today it is being run on laptop computers and the HVAC engineer enters the specific input for the building (s)he is working on.