Anything a little larger (say a 4381) 'back in the day' also needed to be asked politely to be switched off, even PDP-11's running UNIX wouldn't take kindly to an unscheduled drop in input juice. fsck or the local equivalent would be your lot. I'm actually quite happy with the shutdown speed of modern hardware running Linux, it's typically under a second or so but I can see how it might get to you that you can't just throw the switch. It might be interesting to do this on purpose a bunch of times to see what the end result is, I built a car computer once that was arranged purposefully so that losing power at any time did not make it lose stuff but that was quite a tricky setup with a supercap and a bunch of 'early warning' logic to let the computer know that powerdown was imminent. It did work but I was never quite sure how much leeway there was.