In this paragraph, I take a side turn which took far longer to write than the initial thought, as it required me to do some research [re for "again" and then search--as most of this I already knew, but forgotten over time]. Think about the software you use every day. There's not much out there that has a legacy that can reach back that far. [For those keeping score at home, I don't count Microsoft Windows as that long-lived, though with NT's release in 1992, it is close. While a product called Microsoft Windows was actually announced in 198, and the Wikipedia article shows the Windows descendants and the Windows NT descendants merging in Windows XP, I think it fair to say that you can trace the current operating systems more to Windows NT than any of the code base that mostly terminated with Windows Millenium Edition. My $0.02]. Linux users, you also have roots as far back as at least 1983, and your direct code legacy is almost exactly as old as PGP, with the announcement of the Linux kernel in August of 1991.
ObOffTopicArgh: My dad "rescued" my book at the restaurant, but now I'm worried that he left it on the seat next to his when we left.