My retired sister is doing some odd-job consulting for whatever reason. She headed a group in the 1990's that wrote a major tire manufacturers MIS code on IBM computers.<p>Recently she texted me - she'd had to change a module written in 1987. Written 30 years ago, and still in production. Not a person left at that mega-corporation who would have any idea how to do it.<p>Of course her group's old code, still in production, has been hardly touched since she left. And the code IT depended upon still has to run; thus the 20-year-old code requiring 30-year-old code to function.<p>The kicker: she's going to stop consulting in a few months (they don't know it yet). It will cost them millions to retool/retrain with some modern system.