By the way, the one time in my career that I've ever pressed "The big red button that shall never be pressed!" was at RAND.
It is standard for computer room facilities to have a way to kill all power to the equipment quickly in cases of emergency. Traditionally this is a very large red button that can be pressed for this purpose, often just inside an entry door. Typically it's under some sort of plastic shield or such to avoid it being pressed accidentally.
This button is never to be used in the course of normal events. Because it abruptly terminates all power to associated equipment, the risk of data loss and even equipment damage is very significant.
So one day, I walk down the stairs to my basement computer room at RAND where the PDP-11s and ARPANET interfaces lived. I open the door ... and there's nothing there but a wall of white.
When faced with something like that, it takes a couple of seconds to figure out what the hell is going on -- it's not in your brain's expected scenarios for opening that door.
The room was full of white smoke.
Within a few seconds I reached up under the shield just inside the door and slammed down the "never to be pressed" red button.
Instantly power was cut to the UNIX PDP-11s, the ARPANET equipment, a bunch of peripherals, and even a number of disk drives that were in an adjacent room that serviced the big IBM mainframe on the ground floor above.
As it turned out, the Halon fire suppression system was within a few seconds of firing when I killed the power -- management was pretty happy about that since recharging the Halon was expensive.
I got a DEC (Digital Equipment Corporation) CE (Customer Engineer) out to RAND within a couple of hours. He quickly found the source of the problem.
A PDP-11/70 power supply had dramatically failed. It was partly molten slag. Very impressive. I tried to get the RAND photographer down to take a photo of it (this was long before cell phone cameras or even cell phones), but the CE grabbed the power supply, hid it under his coat, and ran out to his car with it.
Apparently he wasn't thrilled with the prospect of photographic evidence of the failure.
Interesting day.
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