It's official: "nuke" infected Windows PCs instead of fixing them

David DeLaney

Almost.

The plant was designed with hydrolic gates that were in a normal "closed" position ... IE-it the power went off, hydrolic pressure would close them. There were two 80,000 ton silos, one with gravel, and one with sand. Gates controled those into a scale, with another gate below the scale to empty it into a mixer. A fourth gate emptied the mixer into the truck.

Now I was involved with the design of the hardware as well, and one thing I insisted on was that the power to the gates be supplied through a large "pull out to enable" palm switch. A big Allen-bradley sucker, marked "emergency stop". In other words, if you hit that switch, the power to the gates would be cut, and the gates would all automatically close. Gauranteed shutoff, right?

I replaced the Proms, and told the driver to get out of the truck for the first test. (He argued, but I insisted. I was brash and green at the time, and insisted on strict safety procedures. He humoured me.) They dialed in a mix (on BCD thumbwheels) and hit the "start" button. Not only did all four gates open, but the machine went into a loop waiting fo the scale to get up to weight. Of course, since the material was falling straight through both scale and mixer, it never did. I hit the emergency off, and THE f***ER DID NOT WORK!

In complete panic, I started at a dead run for the fuse-box room on the floor two down. The control room, of course, was *above* truck level, on the third floor. I got there and it was locked, Screaming "where's the F*ing key", I was told it was up-stairs in the control room. Material kept flowing. I ran up two flights of stairs, got the key. Ran back down two flights of stairs. Unlocked the door. Hit the power switch, and everything closed just as the last few rattles of 3-4" stone landed on top of the pile. The front bumper was all that was visible. With great laughs of glee, the plant operator and truck driver got a front end loader and some chain, and dragged it out from under. I think I snarled something like "next time don't argue when I tell you to get out of the truck", and removed the proms.

I later learned that the plant operator had bumped the emergency switch accidentally, and got so annoyed he asked the electrician to re-wire arround it. So much for failsafe.

The bug was an inversion of the I-O bits on the output ports, so closing all gates at the start opened them all instead. The next time I tested, I tested the damned cutoff first.

Donald