Unisys/Burroughs mainframes running COBOL ca. 1992 (and probably earlier) had this as a feature by default. You could walk up to one of these boxes right in the

Unisys/Burroughs mainframes running COBOL ca. 1992 (and probably earlier) had this as a feature by default. You could walk up to one of these boxes right in the middle of a scary finance, payroll, whatever job, yank the cord out (not recommended), plug it back in, and the machine would boot up and return to what it was doing, usually with no ill effect. Despite switching to a dozen new fad languages since then, programmers have yet to get around to replicating this in any broadly-adopted modern system. If you want to put the effort in to engineering it yourself, of course, you can. But it was nice to not have to engineer it at all. When greybeards seem cranky, it's because of stuff like that.