I'm not the OP but I'm guessing it makes him laugh because you can still run things on Windows that were written in the early 1990s. I have personally worked on

I'm not the OP but I'm guessing it makes him laugh because you can still run things on Windows that were written in the early 1990s. I have personally worked on an application in 2016 that was written in 1989 and still ran. It depended on mainframe code that was written in the 1980s and possibly some from the 1970s. (Yes, it would have to be Windows NT to run I think) Read Raymond Chen's fantastic blog for how much MS have worked to keep backwards compatibility going. And then we come to backward compatibility and mainframes: "The IBM Z family maintains full backward compatibility. In effect, current systems are the direct, lineal descendants of System/360, announced in 1964, and the System/370 from the 1970s. Many applications written for these systems can still run unmodified on the newest IBM Z system over five decades later.[3]" https://en.wikipedia.org/wiki/IBM_Z https://en.wikipedia.org/wiki/IBM_Z It would be interesting to see someone try to see what the oldest unmodified app they could run on a Z series was.