You might be able to make some far-fetched trademark argument about Unix look-and-feel, but what a patent covers is a set of succinct (or sometimes not-so-succinct) claims. Ie, "A system, with provision for input and output to a terminal, that...."
I'm unsure of what exactly SCO's patents cover, but many of the fundamental characteristics of unix look and feel are more than 20 years old, e.g. the patents would be expired by now.
We might have to worry about some things, like System V-style shared memory, possibly being infringing. But it's not really possible to get a patent on the concept of a "unix-like" OS.
Good luck doing -anything- like SMP interfacing logic / interrupt mapping / cache invalidation on 3kgates (read: 800-900 real world logic gates) of FPGA.
I suspect the FPGA will be used more just for I/O routing to slower parts of the device; this is a typical use for low gate count FPGAs and allows easier patching of problems late in the hardware development cycle, and easier addition of features down the road without having to find a way to multiplex a few more signals off the CPU.
This is a typical artifact of RISC chips. Instructions are fixed size, and usually the same size as the general purpose registers. When you load from an immediate value (a value contained in the instruction), the instruction has insufficient room for a value as wide as the instruction itself after specifying the instruction, the destination operand, etc.
I should have taken a moment more to mention tree arbitration schemes, like Maxim's one-wire protocol. Yes, these exist, but they would require the handshake that i discussed to read the data from the RFID tag to take even longer than I cited.
Keep in mind Michelin made a breakthrough to make this thing work 24" for only one stationary device. Is big brother gonna instantly have a system that can make this work over 10's of feet for many devices moving at high speed?
RFID is parasitically powered from the interrogating device. Powering it from a long way away on a moving target seems hard.
Also, you'd need to be able to distinguish from multiple transmissions on the same frequency to recover the serial number. A very high gain antenna (parabolic dish) still has a beamwidth of >= 2 degrees. Being able to power the RFID devices from more than 10 feet away, and also receive the return signal, without giving everyone cataracts from the microwave exposure seems like a hard problem.
Most RFID systems are not truely RF based, but are magnetically/inductively coupled at a relatively low frequency. These are not going to have any kind of range at all, and a high gain "antenna" (directional electromagnet) would be huge.
Finally, vehicles move. Even a speedy RFID tag that transmits at 12kbps takes 1/46th of a second to send a typical 256 bit message (serial number + checksum + overhead). It takes 5-6 times this in practice to power the tag, interrogate it, and receive a response, in which time the car has moved >10ft at 60MPH. So even if you could have an ultra-high-gain antenna, it'd have to be significantly steerable, too.
I'm not very worried. Compared to a license plate/VIN this is nothing.
And uhm, if you're sending focused light through the PUPIL, what exactly do you think you're shining light on? Certainly not the retina-- of course not. That would make sense. Instead I'm sure it goes off into a black hole.
Something doesn't have to be going very fast to cause a 50G deceleration. A few feet of drop onto concrete is plenty.
That being said, chances are the platters and the data will be fine, even if the mechanism of the drive is screwed up.
For a 25 foot fall with (nearly) no drag, the drive will get up to a speed of 40.0 ft/sec (27.3 MPH). If the drive stops over a 1/8" distance, with -uniform deceleration- (this is pretty generous for a fall onto concrete), this equates to 1600 G's. Halve the distance, and quadruple the force. Decelerate it in a non-uniform fashion (as it realistically would) and you'll get even more spectacular results.
See this review of a hitachi drive. Note that they say a drive designed for a non-operating shock of 800G's can take a fall of -one foot- onto concrete. I destroyed a maxtor by dropping it 3 feet onto carpet in a past life, and I'd suspect it was rated for a non-operating shock of at least 50G's.
I'd love to see you try it with your drive with your valuable data sometime though.
Most dynalinking codes allow libraries to cause an initializer function to be run when they're loaded. So the problem you're describing isn't really new and exists on most systems today.
Besides, no system can verify the integrity of itself-- you'll run into Godel's incompleteness theoreum if you try.;)
Breaking 2048 bit RSA is likely to be much more difficult than a birthday attack on the hash algorithm.
However, both are relatively hard; probably the most fruitful path is to search for an implementation error in the boot loader.
One interesting path would be a vulnerability in an Xbox game-- as the Win2k embedded environment does not provide protected access to hardware. Any vulnerability in a game could potentially allow the execution of arbitrary code and thus bootstrapping Linux. Inconvenient, but nice.
Yes, it does. And you can tune in broadcast AM stations on an ADF receiver and see what direction they are relative to you.. that's why they're shown with frequency on aviation charts (as a last-ditch radio navigation fallback).
Most of the realistic studies I've seen have shown a 250-350% annualized growth rate in network traffic. This differs from the Worldcom lie of traffic doubling every 100 days (which is more like a 1200% annualized growth rate). This is likely to continue for some time, due to the increased dependence on the internet, new user bases, and existing apps becoming more bandwidth hungry-- as long as monopolization doesn't hold prices artificially high. Of course it won't continue forever; just like computers, for many people, are becoming "fast enough" and commoditized.
In some ways, the pain that telecom is in now could become our gain in 2-3 years, as the agile providers learn to cope with the smaller margins and snap up all the equipment and fiber cheaply from their defunct competition.
Re:How to automate the process easily
on
Listen To The Leonids
·
· Score: 2, Informative
The problem with this is limiter noise-- FM radios tend to output higher signal levels when they -aren't- tuned to a station than when they are.
Unfortunately meteor scatter doesn't work for MF where AM stations are, but AM radios would be a much better bet (though auto gain control would hide the effect some here, even).
A microsecond is 1 * 10^-6 seconds. 1/400,000,000th of a second if 2.5 nS. 6 microseconds through a HD controller seems quite attainable and is supported by the benchmarks.
The number is a 32 bit int. The maximal value is 2147483647.
Every year, the length of the copyright is increasing by 50. In 2147483647/50 years, the length of the copyright will become -negative-. And yes, 42949673 < -3.
Indeed, running this program:
[offered:~/evilvpn] mlyle% cat main.c main() {
int limitedTime = 14;
int i;
for ( i=0;i<limitedTime;i++) {
limitedTime += 50;
}
There are plenty of attacks that if you reside on the same virtual lan as one of the victims that allow you to intercept traffic.
One is sending traffic from the victim's mac address, so that the switch "learns" that MAC is out your port. Port security features on switches can help fix this but are oft-unused.
Another is ARP spoofing and using that to man-in-the-middle the session. You tell the person logging in that your MAC address is the victim host, and it cheerfully sends all packets to you. This is difficult to detect and prevent.
In conclusion: switches do not provide security against packet sniffing attacks.
A key one is HDCP which makes CSS look like child's play. This extension to DVI will make everyone's life more difficult with devices they use every day-- if Intel's dream of HDCP + DVI being the standard consumer digital video interconnect takes hold.
Just one question-- if reflection is not of concern, why is multipath such a concern when it comes to vhf and above radio frequency reception?
See this for some cursory information on how diffraction works as a propagation mode for VHF and above. It is not uncommon for the TV signals, etc you receive to be on the other side of a mountain. And reflective propagation modes are -heavily- used to obtain cellular coverage in urban areas.
Actually, antennas with directional gain are very often used for non-LOS propagation.
For example, KGO radio, a 150,000W AM station in San Francisco, CA, has an array that is designed to propagate the radio waves up and down the west coast, and not into the mountains to the east or to the ocean to the west. Reception in northern Canada of the KGO signal is not uncommon.
Amateur radio operators often use high-gain antennas for non-LOS propagation modes, as long as the high-gain antennas for the given frequency are of a reasonable size. (Obviously, a directional antenna on 1MHZ, with a 160M wavelength, would be rather large).
It is true that exceptionally narrow-bandwidth antennas, like parabolic dishes, are generally only used for LOS or reflective propagation modes. However, low-element yagis are routinely used for ionospheric propagation, tropospheric ducting, ground-wave propagation, etc.
First, FM is a modulation mechanism; many frequencies only propagate through the ionosphere under rare conditions. This includes the VHF (30MHz-300MHz) used by FM radio and much of TV.
However, VHF is substantially propagated by diffraction and refractive modes. I receive a VHF TV station regularly which is on the other side of a mountain from me.
High bandwidth technologies often require line of sight because other propagation modes create "multipath"-- there are multiple paths that provide nearly equivalent signal strengths. This smears bits together. The bandwidth of what you're expressing limits multipath from being such a concern for FM radio-- to express an audio signal that is mostly under 10KHz, as long as the paths don't differ by more than.00001 seconds, multipath is irrelevent. And the speed of light is pretty darn fast.
I think the overall assumption here is that there's a relatively large number of channels available. The point of the "repeaters increase effective bandwidth" is that everyone can use minimal output power to talk to the closest node on the network, and then it can be re-emitted on another channel to yet another repeater, and so on. The fact that the signal is repeated over small radiuses again and again effectively makes the signal directional-- think about the amount of power needed to send a large signal across a room instead of a path of small spheres of emitted radio energy that in turn crosses the room.
The overall benefit to such a scheme is that total bandwidth is now a function of overall station density and spectrum, rather than spectrum alone. For small numbers of stations (5) unicast radio is more efficient. But as the number of stations increase, everyone participating as a network node greatly increases the available bandwidth.
Woah. I suggest you check out Claude Shannon's information theory.
Basically, the minimal theoretical bandwidth of a signal is the number of bits of information per second the signal carries per second, in hertz.
All ways of modulating a carrier cause other spectral characteristics to appear-- call them "sidebands" or whatever. And filtering them out results in pure sinewave (and thus no information) on the receiver side.
These limitations, being physical in nature, are unlikely to be broken anytime soon. That being said, there are plenty of ways to extract additional "bandwidth" with directional transmissions, minimal output power, etc, thus allowing services to share spectrum.
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You might be able to make some far-fetched trademark argument about Unix look-and-feel, but what a patent covers is a set of succinct (or sometimes not-so-succinct) claims. Ie, "A system, with provision for input and output to a terminal, that ...."
I'm unsure of what exactly SCO's patents cover, but many of the fundamental characteristics of unix look and feel are more than 20 years old, e.g. the patents would be expired by now.
We might have to worry about some things, like System V-style shared memory, possibly being infringing. But it's not really possible to get a patent on the concept of a "unix-like" OS.
Good luck doing -anything- like SMP interfacing logic / interrupt mapping / cache invalidation on 3kgates (read: 800-900 real world logic gates) of FPGA.
I suspect the FPGA will be used more just for I/O routing to slower parts of the device; this is a typical use for low gate count FPGAs and allows easier patching of problems late in the hardware development cycle, and easier addition of features down the road without having to find a way to multiplex a few more signals off the CPU.
This is a typical artifact of RISC chips. Instructions are fixed size, and usually the same size as the general purpose registers. When you load from an immediate value (a value contained in the instruction), the instruction has insufficient room for a value as wide as the instruction itself after specifying the instruction, the destination operand, etc.
I should have taken a moment more to mention tree arbitration schemes, like Maxim's one-wire protocol. Yes, these exist, but they would require the handshake that i discussed to read the data from the RFID tag to take even longer than I cited.
Keep in mind Michelin made a breakthrough to make this thing work 24" for only one stationary device. Is big brother gonna instantly have a system that can make this work over 10's of feet for many devices moving at high speed?
Yes, assuming the different RFID devices can hear each other.
However, I assume they don't have directional antennas that greatly increase the range beyond the specified 24" to hear each other now, do they?
A few points about RFID.
RFID is parasitically powered from the interrogating device. Powering it from a long way away on a moving target seems hard.
Also, you'd need to be able to distinguish from multiple transmissions on the same frequency to recover the serial number. A very high gain antenna (parabolic dish) still has a beamwidth of >= 2 degrees. Being able to power the RFID devices from more than 10 feet away, and also receive the return signal, without giving everyone cataracts from the microwave exposure seems like a hard problem.
Most RFID systems are not truely RF based, but are magnetically/inductively coupled at a relatively low frequency. These are not going to have any kind of range at all, and a high gain "antenna" (directional electromagnet) would be huge.
Finally, vehicles move. Even a speedy RFID tag that transmits at 12kbps takes 1/46th of a second to send a typical 256 bit message (serial number + checksum + overhead). It takes 5-6 times this in practice to power the tag, interrogate it, and receive a response, in which time the car has moved >10ft at 60MPH. So even if you could have an ultra-high-gain antenna, it'd have to be significantly steerable, too.
I'm not very worried. Compared to a license plate/VIN this is nothing.
And uhm, if you're sending focused light through the PUPIL, what exactly do you think you're shining light on? Certainly not the retina-- of course not. That would make sense. Instead I'm sure it goes off into a black hole.
For a 25 foot fall with (nearly) no drag, the drive will get up to a speed of 40.0 ft/sec (27.3 MPH). If the drive stops over a 1/8" distance, with -uniform deceleration- (this is pretty generous for a fall onto concrete), this equates to 1600 G's. Halve the distance, and quadruple the force. Decelerate it in a non-uniform fashion (as it realistically would) and you'll get even more spectacular results.
See this review of a hitachi drive. Note that they say a drive designed for a non-operating shock of 800G's can take a fall of -one foot- onto concrete. I destroyed a maxtor by dropping it 3 feet onto carpet in a past life, and I'd suspect it was rated for a non-operating shock of at least 50G's.
I'd love to see you try it with your drive with your valuable data sometime though.
Most dynalinking codes allow libraries to cause an initializer function to be run when they're loaded. So the problem you're describing isn't really new and exists on most systems today.
;)
Besides, no system can verify the integrity of itself-- you'll run into Godel's incompleteness theoreum if you try.
Breaking 2048 bit RSA is likely to be much more difficult than a birthday attack on the hash algorithm.
However, both are relatively hard; probably the most fruitful path is to search for an implementation error in the boot loader.
One interesting path would be a vulnerability in an Xbox game-- as the Win2k embedded environment does not provide protected access to hardware. Any vulnerability in a game could potentially allow the execution of arbitrary code and thus bootstrapping Linux. Inconvenient, but nice.
I also thought it might destroy their business model; or perhaps completely destroy their business model.
And if you start mandating all this in every car, suddenly there will be no such thing as a sub-$8000 car that real people can afford.
Personally, I like the ability to choose what functionality I get.
Yes, it does. And you can tune in broadcast AM stations on an ADF receiver and see what direction they are relative to you.. that's why they're shown with frequency on aviation charts (as a last-ditch radio navigation fallback).
Most of the realistic studies I've seen have shown a 250-350% annualized growth rate in network traffic. This differs from the Worldcom lie of traffic doubling every 100 days (which is more like a 1200% annualized growth rate). This is likely to continue for some time, due to the increased dependence on the internet, new user bases, and existing apps becoming more bandwidth hungry-- as long as monopolization doesn't hold prices artificially high. Of course it won't continue forever; just like computers, for many people, are becoming "fast enough" and commoditized.
In some ways, the pain that telecom is in now could become our gain in 2-3 years, as the agile providers learn to cope with the smaller margins and snap up all the equipment and fiber cheaply from their defunct competition.
The problem with this is limiter noise-- FM radios tend to output higher signal levels when they -aren't- tuned to a station than when they are.
Unfortunately meteor scatter doesn't work for MF where AM stations are, but AM radios would be a much better bet (though auto gain control would hide the effect some here, even).
Please note:
A microsecond is 1 * 10^-6 seconds. 1/400,000,000th of a second if 2.5 nS. 6 microseconds through a HD controller seems quite attainable and is supported by the benchmarks.
The number is a 32 bit int. The maximal value is 2147483647.
./main
Every year, the length of the copyright is increasing by 50. In 2147483647/50 years, the length of the copyright will become -negative-. And yes, 42949673 < -3.
Indeed, running this program:
[offered:~/evilvpn] mlyle% cat main.c
main() {
int limitedTime = 14;
int i;
for ( i=0;i<limitedTime;i++) {
limitedTime += 50;
}
printf("time: %d\n", i);
}
Prints:
[offered:~/evilvpn] mlyle%
time: 42949673
I hope -you- don't code for a living, freddy boy.
try 40 million on for size instead. (it's +50, not +1)
There are plenty of attacks that if you reside on the same virtual lan as one of the victims that allow you to intercept traffic.
One is sending traffic from the victim's mac address, so that the switch "learns" that MAC is out your port. Port security features on switches can help fix this but are oft-unused.
Another is ARP spoofing and using that to man-in-the-middle the session. You tell the person logging in that your MAC address is the victim host, and it cheerfully sends all packets to you. This is difficult to detect and prevent.
In conclusion: switches do not provide security against packet sniffing attacks.
A key one is HDCP which makes CSS look like child's play. This extension to DVI will make everyone's life more difficult with devices they use every day-- if Intel's dream of HDCP + DVI being the standard consumer digital video interconnect takes hold.
Just one question-- if reflection is not of concern, why is multipath such a concern when it comes to vhf and above radio frequency reception?
7 1
See this for some cursory information on how diffraction works as a propagation mode for VHF and above. It is not uncommon for the TV signals, etc you receive to be on the other side of a mountain. And reflective propagation modes are -heavily- used to obtain cellular coverage in urban areas.
http://www.crc.ca/en/html/crc/tech_transfer/101
Actually, antennas with directional gain are very often used for non-LOS propagation.
For example, KGO radio, a 150,000W AM station in San Francisco, CA, has an array that is designed to propagate the radio waves up and down the west coast, and not into the mountains to the east or to the ocean to the west. Reception in northern Canada of the KGO signal is not uncommon.
Amateur radio operators often use high-gain antennas for non-LOS propagation modes, as long as the high-gain antennas for the given frequency are of a reasonable size. (Obviously, a directional antenna on 1MHZ, with a 160M wavelength, would be rather large).
It is true that exceptionally narrow-bandwidth antennas, like parabolic dishes, are generally only used for LOS or reflective propagation modes. However, low-element yagis are routinely used for ionospheric propagation, tropospheric ducting, ground-wave propagation, etc.
Let me clear things up some more.
.00001 seconds, multipath is irrelevent. And the speed of light is pretty darn fast.
First, FM is a modulation mechanism; many frequencies only propagate through the ionosphere under rare conditions. This includes the VHF (30MHz-300MHz) used by FM radio and much of TV.
However, VHF is substantially propagated by diffraction and refractive modes. I receive a VHF TV station regularly which is on the other side of a mountain from me.
High bandwidth technologies often require line of sight because other propagation modes create "multipath"-- there are multiple paths that provide nearly equivalent signal strengths. This smears bits together. The bandwidth of what you're expressing limits multipath from being such a concern for FM radio-- to express an audio signal that is mostly under 10KHz, as long as the paths don't differ by more than
I think the overall assumption here is that there's a relatively large number of channels available. The point of the "repeaters increase effective bandwidth" is that everyone can use minimal output power to talk to the closest node on the network, and then it can be re-emitted on another channel to yet another repeater, and so on. The fact that the signal is repeated over small radiuses again and again effectively makes the signal directional-- think about the amount of power needed to send a large signal across a room instead of a path of small spheres of emitted radio energy that in turn crosses the room.
The overall benefit to such a scheme is that total bandwidth is now a function of overall station density and spectrum, rather than spectrum alone. For small numbers of stations (5) unicast radio is more efficient. But as the number of stations increase, everyone participating as a network node greatly increases the available bandwidth.
Woah. I suggest you check out Claude Shannon's information theory.
Basically, the minimal theoretical bandwidth of a signal is the number of bits of information per second the signal carries per second, in hertz.
All ways of modulating a carrier cause other spectral characteristics to appear-- call them "sidebands" or whatever. And filtering them out results in pure sinewave (and thus no information) on the receiver side.
These limitations, being physical in nature, are unlikely to be broken anytime soon. That being said, there are plenty of ways to extract additional "bandwidth" with directional transmissions, minimal output power, etc, thus allowing services to share spectrum.