When PIDS acts up ...

Notice those electronic boards that tells you how many minutes till the next train in between the text-ads they display? They're essentially a big PC on the inside with a LAN connection with mission control (Master Control System, MCS) which tells it what to display.

It's never a good idea to have your system crash visible to your customers. That's why you need this seperate little program in these kind of devices to watch over the main program, so that when your trusty main program went crazy, little sidekick can take over and restart things.

These are called Watchdogs, and there are a lot of ways to implement it, hardware and software. The idea is simple enough that there's no reason not to have it in designed into the spec.

But hey, Microsoft Windows 98 demo crashes right in the middle of Bill Gates presenting it, so why not the other guys right?