Is that true? After I initially read that article some months ago, I went searching to find out if Linux did use it. I couldn't find a definitive yes or no but got the impression that it did. If it doesn't, why not? Is it because it CAN be done reliably in software? And even it it can, why NOT let the hardware do it for you?
I just read this article recently in Embedded Systems Programming magazine.
http://www.embedded.com//showArticle.jhtml?article ID=55301875
After a detailed explanation of the hardware protection features built into the x86 (since the 80386), the author makes the following statement towards the end of the article:
"Too bad Microsoft doesn't use this feature. Windows has been plagued by buffer-overflow bugs that could easily be prevented by the processor's segmentation features. Alas, even though these features have been built into every x86 chip for more than 15 years, Microsoft has never used them. Instead, Windows creates a "flat" memory system with no segmentation, no tasking, no bounds checking, and no privilege protection, and then struggles to duplicate all those features in software. The result has been famously ineffective."
I would like to see device manufaturers get out of the device driver writing business, have a genuinely generic driver in the O/S and discover the repetoire of a particular device by reading a configuration file - preferably one that can be read from the device. From a pragmatic point of view XML would probably be a good match for the task since you would inevitably need structured data and a way to extend the basic data structures."
In the industrial controls market, Allen-Bradley/Rockwell Automation has been doing something similiar to define the characteristics of their hardware. Each device has an EDS file (electronic data sheet) that "describes a product's device type, product revision and configurable parameters".
How about a 6802 ??
http://www.carrollsweb.com/dougrb/pics/6802.jpg.
Found this somewhat of a coincidence that I just dug this out of my bench a week ago after building it almost two years ago. It flashes the LED's left and right ala Kit. Lost the source ASM so read out the hex code from the eprom and reconstructed the assembly.
Anyway, the IBM PC was just coming out in my 3rd year of college (BSEE) and the assembly language classes at the time were on PDP-11's. Since the IBM's were around the teacher I had gave us the option to work on them instead of the PDP's. I LOVED that stuff and dove right in. I think the deeper understanding on what's going on has helped me tremendously. But then I do work in industrial controls with PLC's, which can be a lot of bit banging.
The problem I have with this analogy is that most people can determine on their own whether their house/car is reasonably secure against break-in. Most people cannot do this with their computer.
You are right about the internal resistance, but you will not notice anything grabbing on to the terminals of a car battery. I just measured the resistance between my left & right hands... around 500,000 ohms. 12V divided by 500,000 equals 0.000024 amps, or 24 microamps. A GFI breaker in your kitchen or bathroom, which detects current flowing through some other path besides ground (like your body) will trip at around 0.005 amps. Anyway, if it acually was harmfull, do you think they would leave all that wiring under the hood open ?
That was 100,000 volts with NO LOAD. Your body resistance loaded down the power supply and it was no longer 100,000 volts (probably 10's of volts). Take a 9V and 2 1.5 V batteries and put them in series. You now have 12 volts. Hook that up to your car and try to start it. Nothing will happen because the starter will load down the 12V to almost 0V. A battery can be modeled by an ideal voltage source (one that can put out infinite current) in series with a resistor. The difference between the above mentioned 12V battery and your car battery... the value of that resistance (100's of ohms in the first case, 10's of thousanths in the second).
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When I was in Dallas once, someone said that speed limits in Texas are just a suggestion.
In Opera, F12 and uncheck "Enable GIF/SVG Animation"
My son got Quicken to run in Crossover. Don't know details (flavor of Linux or version of Quicken).
Is that true? After I initially read that article some months ago, I went searching to find out if Linux did use it. I couldn't find a definitive yes or no but got the impression that it did. If it doesn't, why not? Is it because it CAN be done reliably in software? And even it it can, why NOT let the hardware do it for you?
I just read this article recently in Embedded Systems Programming magazine. http://www.embedded.com//showArticle.jhtml?article ID=55301875
After a detailed explanation of the hardware protection features built into the x86 (since the 80386), the author makes the following statement towards the end of the article:
"Too bad Microsoft doesn't use this feature. Windows has been plagued by buffer-overflow bugs that could easily be prevented by the processor's segmentation features. Alas, even though these features have been built into every x86 chip for more than 15 years, Microsoft has never used them. Instead, Windows creates a "flat" memory system with no segmentation, no tasking, no bounds checking, and no privilege protection, and then struggles to duplicate all those features in software. The result has been famously ineffective."
It would be nice if it searched inside ZIP files.
I was getting ready to comment something similiar but your "collateral damage" thing is SO much better than what I was going to say.
OR... "Here... hold my beer"
In the industrial controls market, Allen-Bradley/Rockwell Automation has been doing something similiar to define the characteristics of their hardware. Each device has an EDS file (electronic data sheet) that "describes a product's device type, product revision and configurable parameters".
www.ab.com/networks/eds/
July 30, 2PM ET
_ ke y=18
http://www.g4techtv.com/show_schedule.aspx?show
this would have been even cheaper
http://vunct.com/~jasonalter/googlekeys.jpg
http://groups.google.com/groups?hl=en&lr=&ie=UTF-8 &threadm=6019bc74.0406262005.21439b64%40posting.go ogle.com&rnum=2&prev=/groups%3Fq%3Dfreeipods.com%2 6hl%3Den%26lr%3D%26ie%3DUTF-8%26selm%3D6019bc74.04 06262005.21439b64%2540posting.google.com%26rnum%3D 2
How about a 6802 ?? http://www.carrollsweb.com/dougrb/pics/6802.jpg. Found this somewhat of a coincidence that I just dug this out of my bench a week ago after building it almost two years ago. It flashes the LED's left and right ala Kit. Lost the source ASM so read out the hex code from the eprom and reconstructed the assembly. Anyway, the IBM PC was just coming out in my 3rd year of college (BSEE) and the assembly language classes at the time were on PDP-11's. Since the IBM's were around the teacher I had gave us the option to work on them instead of the PDP's. I LOVED that stuff and dove right in. I think the deeper understanding on what's going on has helped me tremendously. But then I do work in industrial controls with PLC's, which can be a lot of bit banging.
soon I'll be able to find that lost sock after washing clothes on google.
The problem I have with this analogy is that most people can determine on their own whether their house/car is reasonably secure against break-in. Most people cannot do this with their computer.
You are right about the internal resistance, but you will not notice anything grabbing on to the terminals of a car battery. I just measured the resistance between my left & right hands... around 500,000 ohms. 12V divided by 500,000 equals 0.000024 amps, or 24 microamps. A GFI breaker in your kitchen or bathroom, which detects current flowing through some other path besides ground (like your body) will trip at around 0.005 amps. Anyway, if it acually was harmfull, do you think they would leave all that wiring under the hood open ?
That was 100,000 volts with NO LOAD. Your body resistance loaded down the power supply and it was no longer 100,000 volts (probably 10's of volts). Take a 9V and 2 1.5 V batteries and put them in series. You now have 12 volts. Hook that up to your car and try to start it. Nothing will happen because the starter will load down the 12V to almost 0V. A battery can be modeled by an ideal voltage source (one that can put out infinite current) in series with a resistor. The difference between the above mentioned 12V battery and your car battery... the value of that resistance (100's of ohms in the first case, 10's of thousanths in the second).