The "**software**" comprising the carefully planned interpretive routines, compilers, and other aspects of automative programming are at least as important to the modern electronic calculator as its "hardware" of tubes, transistors, wires, tapes and the like.

1958, John W. Tukey, "The Teaching of Concrete Mathematics" in The American Mathematical Monthly, vol. 65, no. 1 (Jan. 1958), pp 1-9