Vernor Vinge's 1999 novel
A Deepness in the Sky depicts a human interstellar culture that relies on software written over five thousand years, some from "before Humankind ever left Earth". Its computers still "can run most of them" through "a million million circuitous threads of inheritance ... layers upon layers of support". "Down at the very bottom" of the culture's "incredibly complex" timekeeping systems, for example, "was a little program that ran a counter [from]
the 0-second of one of Humankind's first computer operating systems".
Programmer-archaeologists find and modify old software written hundreds of years ago (one character states that "all of them are buggy") to solve modern problems.