I've had to use the 7-second rule on the power button on every computer that I've dealt with in the last 10 years (Don't anyone tell my wife that I've told her 10 seconds so her impatience won't cause the hard shutdown process to fail.). The process usually works and shuts off the power supply OK.
This shutdown process works only when the CPU is the one to go dumb and needs power removed so it can start over.
I've had to remove the battery at some point from 2 different laptops and the power cord from every one of the desktops I've owned in the last 10 years. The last incident was probably 6 months ago.
You would think that the timer circuit would be so simple that nothing could go wrong but we've all seen ample evidence that Murphy cannot be defeated.
On most PCs built in the last decade, if the computer is locked up and won't respond to any soft buttons, press and hold the power button for at least five seconds and it will be forced off. It's worked for every desktop and laptop machine I've ever tried it on. No need to yank power sources.
A number of home PC systems don't have a hard power switch on the back side. The theory, of course, being that the software will always shut-down the computer. That works well... Not.
Fortunately, with the case of a desktop PC, the power cord can always be yanked. I've had to remove a laptop battery once for the same reason.
I agree. And what about those stupid cars that have one button to ask the computer to "please start", and the same button for "please stop", the problem being that the computer would decide to not shut off the engine because the car was in motion, when the reason for requesting the stop was engine runaway. That is what is known as "a clearly obvious engineering error".
Even worse with some diesel engines is that if the vehicle rolls over, enough lube oil can get into the cylinders to keep the engine running for quite a while. That is a bad show all around. Some of them now have an air-shutoff valve for emergency stop.
Many, many moons ago I worked with Fuel Management Dispensing Systems for places with their own fleet of vehicles and gas pumps. Due to local bylaws, some locations required locking emergency stop buttons to be beside the pumps. All of these were wired to completely disconnect the power source in the event of an emergency (usually spill related). Can you imagine if this was designed with a soft switch? I'd hate to be the guy that has to hold the button for 10 seconds as gasoline flows freely all around me. Not to mention the possibility of a spark when working with a live circuit.
You press a clutch and break and you stop straight away. One of the advantages of manual drive is that if the engine goes funny just disconnect it mechanically using a clutch.
I remember when an "unexpected acceleration bug" happened with Toyota cars it was hard for many people here in Europe to understand where the problem was - everyone would just say: can't you just press a clutch?
Much worse: in some Renault Scenic cars running on Diesel fuel, there happened a crack in the engine crankcase that had for effect that the engine lubrification oil could go into the engine combustion chambers. This way the diesel engine (which can also run on oil when sufficiently hot) was running on its own with the accelerator pedal having absolutely no effect. No way to switch off the engine (there is no spark plug in a diesel block), no way to reduce RPM except running uphill (or in a tree).
This "feature" scaried a few french drivers (on hiways) but thanks chance, killed nobody (as far as I know). Renault didn't talk alot about this.
The only way to stay alive in that case is to brake as hard as possible and hope the brakes won't overheat until the car stops. As it's a manual geared car, if you press the clutch pedal, the car may slow down but the engine goes up in the RPM like hell, without any limit. Terrifying for the driver and passengers.
I have often found myself in a meeting where my computer has "locked up" and requires a restart. The only method that I had to silently restart was to pull a pair of earphones out of my pocket and plug them in. Of course, this would have worked fine (presumably) with a cheap MP3 player..
NASA's Orion Flight Software Production Systems Manager Darrel G. Raines joins Planet Analog Editor Steve Taranovich and Embedded.com Editor Max Maxfield to talk about embedded flight software used in Orion Spacecraft, part of NASA's Mars mission. Live radio show and live chat. Get your questions ready.
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