I’ve never worked with major enterprise or government systems where there’s aging mainframes — the type that get parodied for running COBOL. So, I’m completely ignorant, although fascinated. Are they power hogs? Are they wildly cheap to run? Are they even run as they were back in the day?
One thing I miss about the old IBM mainframes is the console keyboard had a little LED “Wait” light. If it was on you weren’t using much CPU. But if you got it to turn off or mostly off you were really working out the system.