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Comment: Re:Malicious code can cause computers to crash (Score 1) 138

by Macman408 (#48669711) Attached to: Many DDR3 Modules Vulnerable To Bit Rot By a Simple Program

It depends a bit on the physical structure of the RAM, but for the most part, the errors fall on logically adjacent rows (i.e. nearby memory addresses) in the RAM. So most of the time, you'll only affect other RAM inside your sandbox, and if you affect something outside the sandbox, it won't be far outside.

I remember encountering a similar failure when designing a system; the particular memory controller and the particular DRAM module we were using both met all applicable specs, but when used together in a particular manner, they would fail miserably. The specific test was to alternate writing all zeros and all ones at different addresses. The RAM controller had an oddity where it would enable the drivers for the RAM data pins a very briefly before the data was known. For that particular data pattern, that meant that it would drive all ones on the data pins to the RAM for less than a nanosecond, before starting to drive all zeros (or the reverse). There's nothing really against that in the spec; the data was all correct for all the relevant setup and hold time requirements relative to the control signals. However, it caused a lot of noise on the ground plane of the DRAM module; we measured as much as 0.75V or so. (That's measuring the ground voltage on one side of the SO-DIMM to the ground voltage on the other side; it's shorted by a mostly-solid layer of copper, but that just wasn't enough to carry all the current with this particular access pattern.) So from the point of view of the RAM chips, it's a little like having your 2.5V supply voltage suddenly drop to 1.75V. It messes up all the reference voltages, so a 1 might be interpreted as a 0, or vice versa. The memory controller manufacturer refused to do anything about it (and it would've taken them many months to redesign and respin the chip anyway), but the RAM module manufacturer was friendly to us, and they beefed up the ground plane so that the noise level was much more manageable.

In any case, I'm sure there are thousands of faults like this that are just waiting to be found and exercised in any given system. No modern computer is 100% tested, they're far too complicated. There will always be some weird sequence of things that could happen and trigger some failure - but hopefully that sequence is so odd, it'll never happen.

Comment: Re:Not seeing the issue here (Score 2) 209

by Macman408 (#48650507) Attached to: Judge: It's OK For Cops To Create Fake Instagram Accounts

Negative. When I served on a jury, the judge *specifically* instructed us that we were not to lend any more credence to the testimony of a police officer than to any other person, solely because he/she was an officer. During jury selection, anybody who either would never trust a cop *or* would *always* trust a cop was dismissed.

That said, we trusted the cops anyway, because their story made a lot more sense than the guy and his wife saying "nuh-uh, that meth wasn't mine, bro," with no other evidence or witnesses to prove it. Meanwhile, the police presented evidence such as the meth pipe, the letters addressed to him that the pipe was sitting on top of in his bedside table, the meth that was in it, and a record from his roommate/alleged dealer/meth cook that he was indebted (the presumption being that it was for meth).

I won't disagree that they are probably trusted by a jury more often than other witnesses for a variety of reasons (a lack of obvious motivation to lie, an appearance of professionalism, a calm demeanor under pressure, etc.), but the court itself does not hold them up as model witnesses.

Comment: Re:I'm shocked. (Score 1) 191

by Macman408 (#48614469) Attached to: Apple Wins iTunes DRM Case

I was on a jury recently (for someone accused of misdemeanor possession of methamphetamines). Some of the questions that the judge asked every potential juror were exactly along this line:
- Do you actively participate with any groups that advocate for or against the legalization of drugs?
- Do you believe that possession of a small amount of drugs should be legal?
- (If either of the above was true:) Will you follow my instructions regarding the law, even if it disagrees with your beliefs?

Anybody that wasn't willing to follow the judge's directions was excused from service.

Of course, that also meant that a surprisingly large fraction of the people in the jury room claimed that they either used meth themselves, wouldn't convict someone of meth possession, or had a close family member or friend that used it; and that they wouldn't follow the judge's instructions on the law - they all knew they would be immediately excused and not have to show up for the rest of the week.

I told the truth, and ended up on the jury. It was an interesting process... Plus I got $68.16 to compensate me for my week's worth of time!

Comment: Re:UPS (Score 1) 236

by Macman408 (#48438209) Attached to: What is your computer most often plugged into?

I honestly don't know how much it applies to desktops, but certainly in other form factors, you can't rely on TDP as an indicator of the size of power supply needed. TDP tells you how much heat the heatsink needs to be able to dissipate. If you exceed the TDP for a few seconds, there's enough thermal mass that you won't exceed the maximum junction temperature of the chip, as long as you keep your average power (on the scale of seconds or minutes) below the TDP. Indeed, many devices like laptops, tablets, and cell phones rely on this for maximum performance; if you load a web page, the CPU will ramp up well above the sustained TDP in order to render the page, relying on the fact that the CPU will be nearly idle or off while you read the page after it has rendered, so the average power will be below the TDP.

Instead, there is a different parameter - sometimes referred to as EDP. This tells you the power that the power supply needs to be able to provide, more on the scale of milliseconds (so a long enough timescale that the capacitors on the board can't keep up with the power demands, but not so long that the TDP starts to limit you). EDP is always higher than the TDP.

As I said, I don't build my own computers though (I just design them ;-)), so I have no idea if that's something that has worked its way into choosing a power supply yet. It doesn't seem like it, from some googling.

Other things that can make a difference are inrush current and power factor. I have a desktop that has about a 950W power supply. Typical power draw is on the order of 150 watts or so. So you'd think that a quality UPS with a 900 VA rating should be plenty - unfortunately, when powering it on or waking it, either the inrush current or the power factor as it charges all the inductors and capacitors in the power supply exceeds the capacity of the UPS about one in every 10 times. In that case, the UPS lights up its "Overload" light and shuts off, which rather negates the whole point of a UPS. Additionally, because turning on a light switch with a lot of CFLs often causes enough disturbance to the power to trip the UPS, and the UPS activating causes it to wake the computer, it happened that turning on a light switch would often cause my computer to be immediately disconnected from power, as it would hit the overload condition.

So I moved the UPS to my TV and network connections, and put my computer back on a surge protector. Everything is much happier now.

Comment: Re:Ehhh Meh (Score 4, Informative) 127

by Macman408 (#48394539) Attached to: US DOE Sets Sights On 300 Petaflop Supercomputer

There are plenty of things that can use all the computing power you can throw at it these days. As you mentioned, weather forecasting - though more generally, climate science. Somebody from one of the National Labs mentioned at a college recruiting event that they use their supercomputer for (among other things) making sure that our aging nukes don't explode while just sitting in storage. There are thousands of applications, from particle physics to molecular dynamics to protein folding to drug discovery... Almost any branch of science you can find has some problem that a supercomputer can help solve.

Additionally, it's worth noting that these generally aren't monolithic systems; they can be split into different chunks. One project might need the whole machine to do its computations, but the next job to run after it might only need a quarter - and so four different projects can use the one supercomputer at once. It's not like the smaller computing problems end up wasting the huge size of the supercomputer. After all, many of these installations spend more in electricity bills over the 3- or 5-year lifetime of the computer than they do to install the computer in the first place, so they need to use it efficiently, 24/7.

Comment: Re:As I think has already been pointed out (Score 1) 286

by Macman408 (#48218427) Attached to: Tech Firm Fined For Paying Imported Workers $1.21 Per Hour

I think that's where the determination of willful violation versus accidental can make a difference. Sure, if they knew they were violating the law and did it anyway, then they absolutely deserve a bigger punishment. If it's just a case where they didn't really consider the implications of bringing foreign employees to their US office, a small penalty isn't unreasonable. If they weren't willfully violating the law, they're more likely to follow it for its own sake, rather than due to a financial threat.

Comment: Re:$3500 fine? (Score 5, Interesting) 286

by Macman408 (#48216835) Attached to: Tech Firm Fined For Paying Imported Workers $1.21 Per Hour

It's not clear to me that it was willful avoidance of paying minimum wage - they had a job to do, they got help from some of their existing employees from overseas, who continued to receive their regular wage (in their regular currency) during the time that they were here. So the company paid the back wages to the employees, and a small fine to the government. Doesn't seem unreasonable to give them a little slap on the wrist; save the big punishments for when there are repeated offenses, or more wanton abuse.

I'm more curious what the legal requirement is for paying the local minimum wage instead of a worker's regular salary, when they are working away from their normal office. I certainly wouldn't want to be paid in rupees if I had to travel to an office in India. But if I were there under the same conditions as those workers were here, would there be any violation of US Labor Laws if they paid me the local wage while I was over there? On the other hand, if I go to a college recruiting event in San Francisco for an afternoon, am I entitled to an increased minimum wage of $10.74 for a few hours? What if I'm a driver, paid by the mile, going through different jurisdictions each with their own minimum wage law?

Comment: Re:Three years and counting (Score 1) 278

by Macman408 (#47408515) Attached to: My most recent energy-saving bulbs last ...

Make sure you're not confusing the "white" you see with, for example, LED flashlights, with the "white" that you would get if you bought good LED lightbulbs. The Philips ones are especially good, in my experience. You can get them in usually at least 3 different colors; warm white, cool white, and daylight. Warm white, usually around 2700K-3300K color temperature, is what most people have in their homes; it's the same as tungsten, and is considered "relaxing". Cool white is more bluish; something like 5000K. It is more often used in offices, because studies show that people are more productive with cooler-colored lighting (perhaps because it's closer to the color of noontime sun than tungsten, which is more like sunrise or sunset). It's also used in kitchens and bathrooms, because it's a fairly neutral color. Finally, daylight is the bluest color, at 6500K; it's also used in work areas or factories and places like that.

Sometimes, the cheapest and most efficient LED bulbs are in the blue end of the spectrum, especially when the color temperature doesn't matter too much - like a flashlight. So cheap lights will have a poor blue color to them. But good quality lights can give you any color you want - so you can pick which color looks best to you. I'd recommend seeing if there is a home improvement or other store in your area that sells light bulbs and has a display so you can compare a variety of lamps when turned on.

In the end, LEDs basically have it all; instant-on like tungsten, longer lifespan and lower energy usage than CFL, and available in any color you like. Not all of them support dimming, and not all dimmers support LEDs, so that's something to be aware of, if you have any dimmer circuits. I replaced nearly all of my bulbs with LEDs (and one of my four dimmers), and you'd never know the difference. My power bill sure does, though...

Comment: Re:Long term jobs are rare and getting rarer. (Score 1) 282

by Macman408 (#47395793) Attached to: Ask Slashdot: How Often Should You Change Jobs?

A not-entirely-dissimilar story; I worked for a small company where there was an HR manager and two assistants. During the downturn in 2000, they had to lay off a number of employees, so the manager directed one of the assistants to prepare and assemble kits for each of the earmarked employees giving them information on the benefits and resources available to them. At the meeting where the layoffs were announced, the assistant handed out these packets to the employees, and was then handed her own by the manager. (Ouch.)

Several years later, when things weren't looking terribly rosy, the HR manager quit; there were rumors that there might be another round of layoffs to come, and she didn't want to go through the painful process of doing them again. (Despite the rough delivery above, she was genuinely a nice person; just forced to be less compassionate by corporate need. Case in point; I burned my finger on a soldering iron while at work, and stopped by her office to ask if we had any ice available. I could see on her face that her first reaction was genuine concern and sympathy, followed very shortly afterwards by an "oh dear, there's going to be some paperwork associated with this" look.)

Luckily, we mostly avoided the feared second round of layoffs - 7 people were let go, which was probably more just thinning the herd than layoffs due to purely financial concerns. Thankfully, I had left by the time that the office was shut down several years later. I think everybody knew it was a sinking ship, but nobody was motivated enough to find a different job until they had the engineers packing boxes and disassembling office furniture.

Comment: Re:I can't buy one (Score 3, Interesting) 377

by Macman408 (#47252351) Attached to: Are US Hybrid Sales Peaking Already?

I'm going to go ahead and assume that you didn't buy a "really fat kid" for yourself, and 'splain some things that I've learned as a nerdy Prius owner...

First, it's not gutless as you might think. It's not going to win any awards for acceleration, but it can do 0-60 in 9.7 seconds. That's probably on the slower half of the scale, but still faster than a Yaris Hatchback or Matrix, as well as non-US models like the Avensis, Aygo, or Auris - and that's looking only at Toyota sedans. Most of the gutlessness comes from us schmucks inside the car, who are in no hurry to rush you to the next red light when we can get there at the same time as you, and with half as much fuel, by taking it easy. Some of the gutlessness comes from a software setting that adjusts the throttle response to the gas pedal's position; in Eco mode, you really have to mash the pedal if you want to move, while PWR mode makes it more like most American cars where it's jumpy if you so much as look at the gas pedal. In between is "Normal" mode. There are plenty of Prius owners who hate the car in anything but PWR mode because they like to accelerate fast.

Second, it is a HUGE car on the inside relative to most of my friends' sedans. A good amount of the space is vertical, so it helps if whatever you're carrying is tall or can be stacked. But I've carried 3'x8' sheets of plywood, an 8-foot ladder, or 4 people and backpacking gear for a 4-day wilderness trip. Many people can carry several bicycles inside the car without taking them apart - my wife and I are both very tall, so we have to take off the front wheel of our bikes to fit our bikes in. Out of all my friends, none have cars that can carry any of those things - except one bicycle with the wheels removed, and the handlebars sticking out the window.

Third, I'd say it doesn't really have two power trains; it has one power train of which the gasoline engine and two motor-generators are an integral part. The car would be incapable of driving if any of them are removed, although it'd be easier to remove the gasoline engine if anything. The Prius doesn't have a normal transmission; there are two planetary gearsets that connect the MGs and engine to the wheels. By adjusting the speed and direction of the MGs, pretty much any gear ratio can be obtained. It's sometimes called an "eCVT" because of this, but it could just as easily be called a single-speed transmission. Get rid of the electronic parts of the powertrain, and you'd have to put in a transmission instead to replace it. Also, you'd lose the regeneration abilities of being a hybrid. Of course, if you remove the engine, you'd have to use a much larger battery instead - and even then, the Prius motors are not designed for high-speed use (over 45 mph, the engine has to be spinning to keep the motors from over-revving; I think the limit is about 60 mph in the plug-in variant of the Prius). So both halves of the powertrain are really required for it to work, much less for it to work as efficiently as it does.

That's not to say it's a car for everybody - and indeed, if your choices come down to a Tesla anything or a Prius, I'd go with the Tesla any day unless you plan on regularly exceeding its range in areas where high-speed charging is not available. But it's a good choice of cars for many people.

That said, I'm not surprised that hybrid sales occasionally have a down year - but the trend still seems to be pretty positive. Even though they mention share dropping from 2009 to 2010, the hybrid share is still up about 15% since 2009, at about 3.2% of all cars. Meanwhile, EVs are starting to take off, and often catch the attention of the same eco-minded type that was purchasing the early hybrid models years ago. Still, they only amount to about 0.6% of all vehicle sales. But I don't think hybrids are a long-term solution, just like gas cars aren't either. Unless we start synthesizing gasoline from something other than oil, we'll need to find an alternative fuel sooner or later - whether that means EVs or something else, only time will tell.

All I can say is that I hope Tesla gets other auto makers fired up, otherwise I may have to find a big pile of cash next time I want to buy a car...

Comment: Re:The Woz actually came on /. to talk about this (Score 1) 307

by Macman408 (#47189187) Attached to: GM Names and Fires Engineers Involved In Faulty Ignition Switch

You're misunderstanding. (And I didn't really try to explain it thoroughly, so here you go:)

There are several displays. The speedometer always shows the actual speed. There is another display to the right of the speedometer that shows various settings relating to the radar cruise control - the set following distance, whether the system detects a car in front of you, the set speed, and (if the Lane Keep Assist feature is turned on) whether the car has detected the lane edges or not.

When turning on the cruise control, the set speed shown on the right display is equal to the current speed. When you use the Accel or Coast buttons, it adjusts the set speed shown on the right display, independently of whatever speed you are actually going. Because of this, you can adjust your set speed even when the system is going slower than the set speed due to traffic in front of you. Also because of this, you can adjust your set speed much faster than the car is capable of reacting to match.

There is something to be said for consistency - for example, the Prius fakes "engine drag" when you let up on the accelerator, by drawing power off of the electric generator and charging the battery. It is also programmed to have creep like an automatic car does, where it starts crawling forward when you let off the brake pedal. Both of these are done to make it feel like any other car; there's no inherent reason that it needs to do these. Woz's difficulties with the cruise control stem from the fact that they depart from the standard cruise control behavior. On the other hand, if they didn't, performing some actions (like adjusting your set speed) would be much more difficult, so I don't really fault them for it. Honestly, if you're paying $30k+ for a car with all the bells and whistles, you really ought to RTFM. It may be *mostly* like every other car you've ever driven, but it will also answer a lot of questions you'll probably have, and even a few you didn't know you had.

Remember -- only 10% of anything can be in the top 10%.