Re:The originals really are something else
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Homebrew Cray-1
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· Score: 1
"Why," you may ask, "was the internal wiring so insanely packed?" The length of each point-to-point wire was individually calibrated, such that all the signals to each gate arrived [after a known amount of time delay]...
Cray did this from his earliest designs for Control Data.
His first machines were the CDC 160 (a low-power I/O processor) followed by the CDC 1604 (his first "mainframe"). I "cut my hacker teeth" on a 1604-B, serial number 6.
That was a 48-bit machine (with two instructions per word to save fetch time - he was already thinking speed and inventing RISC).
- The box was in the form of eight swing-out doors, two wide x two front/two back, with the hinges in the middle and the interconnects between the doors in the form of flexible (round) cables plugged into sockets along the hinge-side of each door.
- Each door was a six-bit slice of the ALU plus a share of the instruction sequencer. It had a little power supply in each corner (fed 3-phase 400 Hz power so the transformers were small), six bits of core memory in the center (arranged in even/odd banks so memory access and computation could overlap). The rest of the door was rows of 15-pin card sockets for these little playing-card sized logic cards using discrete components - resistors, diodes, transistors, capacitors. (ICs were available. But Cray used discrete transistors because they were faster.) The cards around the core planes were the memory control, the cards around that were the ALU slice, and the bottom two rows were the instruction sequencer.
The card-side was out on the outer doors and in on the inner - cooling air went up shafts in the center and on just under the outside covers of the unit. The backside of each circuit door, under a door-sized sheetmetal removable cover, was a rats-nest of wires. These were color coded by length and ended in "taper pins". The top three pins of each card were ground and two power inputs, the rest were logic levels. Each pin in the socket had two taper-pin sockets on the back, so two wires could connect to it...
Excluding some special cards the bulk of the cards implemented logic functions using diode-diode-transistor logic. Several multi-input AND gates feeding a multi-input OR gate feeding an inverter transistor. But the way this was arranged was particularly cute: The interconnects were NOT the output of the inverters. They were the summing junction of the and gates.
Each inverter transistor's collector fed several output pins through the diodes of the next stages' AND gates. Wires were daisy-chained from one output to another across all the inverters that drove a given AND term, and also connected to the input pin on the card that finished the and gate. (Think "wired AND".) The input pin on the next stage card had the pullup resistor for the AND gate and a diode to the pulldown resistor for the OR gate and the base of the next stage inverter transistor (along with the far ends of the diodes from the OTHER OR inputs that drove that inverter). There were several card types, with different numbers of inverter transistors, output diodes, and input AND and OR terms.
Re:The originals really are something else
on
Homebrew Cray-1
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· Score: 1
... nearly as much as I've wondered why the hell [the seats] were there in the first place.
As I recall the Cray was curved with wedge-shaped boards and wiring on the inside of the curve to minimize the length of interconnecting wires and thus maximize logic speed. The outside of the tower was for access to the cards. And that meant the power supplies, cooling plumbing, and other support miscellany had to go somewhere else. "Somewhere else" was further out and at floor level - to be out of the way of access to the cards, which means under the "seats".
Given that people would sit on them (or kneel on them to get to the cards when doing maintenance) anyhow, I'd ASSUME they were padded to avoid injury - making them look like bench seats, but not necessarily be comfortable when used as such.
= = = =
I hear the cooling system had an open space just big enough to hold a six-pack. And the amount of time it took to diagnose, gracefully shutdown and cool down, swap in a replacement board, power up, bring to stable temperature, and run diagnostics, was about the time it took to cool the six-pack to ideal temperature for a "Miller Time" moment when the job was done.
And I hear Cray claimed that this was completely coincidental, rather than a design feature. B-)
Re:The originals really are something else
on
Homebrew Cray-1
·
· Score: 1
"Why," you may ask, "was the internal wiring so insanely packed?" The length of each point-to-point wire was individually calibrated, such that all the signals to each gate arrived at the same moment, so you didn't need flip-flops to latch values in the flow of the circuits.
Deskewing the signals didn't eliminate the need to flop the levels - by a long shot.
What it's about is arranging the placement of gates and routing of signals so you avoid situations where most of the inputs to a logic function have arrived but there's one that's taking a long time - so your output isn't right for a considerable time after the inputs change. By getting everything together at the same time you eliminate the long run and get the answer sooner. This lets you have more layers of random logic between the layers of latches, which gets more steps of computing done between ticks of the clock.
These days it's done on chips by the "place and route" tools. Back then the machines were simple enough that it could be done by some smart engineers thinking hard - and techies hooking up the interconnections with wires color-coded by LENGTH, rather than by what signal they carry.
That is an interesting narative. I'm amazed that the investigators were able to obtain temperature records that the CRU admits that they lost. Or I should say, admitted they lost after numerous FOI requests.
Additionally, there's a difference between allegedly "being able to obtain them in three days" and obtaining them with a traceable chain of custody and records allowing them to be rated for accuracy and completeness, making them a suitable foundation for analysis to support or refute - and possibly extend - the original scientists' work.
It often strikes me as an interesting thing that we have no social mechanism for turning down a technical capability, even when we largely believe it's a bad idea.
Sure we have mechanisms for turning down a technical capability.
It's called "personal choice". \ Freedom means each person gets to make that choice for his/her SELF.
"Social Mechanism?" You mean "way for a group to impose its choices on those who disagree with them", don't you?
The closest you have in a free society is persuasion. And others get to argue the other way, or just ignore you. When persuasion becomes social pressure to conform, freedom is replaced by groupthink.
Ummm, I'm confused. The frequencies that GSM uses are licensed by the FCC to specific operators. The phones are used under the control of the operator, who has a license for each and every cell site.
This group, (The OpenBTS project) has permission from the carrier with the license for the area (who doesn't happen to have a cell covering the site) to use the band there.
Additionally (as others have pointed out), they have a specific short-term ("experimental") license to perform this test during the period including the festival and the runup to it. This license includes the right to stimulate the cellphones into operation.
The group also provides emergency service to disasters that have taken out the cellular infrastructure, until the carriers can get it back up, and makes low-cost base station equipment designs (using off-the-shelf hardware) available to third-world countries. ($10k and dropping.) The burning-man event gives them an annual opportunity to do an acid test on their latest software and hardware.
... what happens when half a dozen people in an area with existing service start setting these up and interfering with the big companies who are selling service?
Just what you'd expect: The FCC hunts 'em down and shuts 'em down if they're strong enough to be noticed and especially if they interfere with the license holding service provider for that area and band.
Unlike WiFi, but like broadcast radio, the DSM protocols don't support sharing a given band in a given area. The license holders carefully design their cell site arrangements so their own cells don't step on each other (and nearby neighbors near the edge of their area). If you set up an unlicensed homebrew minicell on band that's in use and don't do it inside a shielded box, you'll trash the licensed service and be in deep kimchi, just as if you wiped out a broadcast station with your pirate radio.
Which is why the OpenBTS project was careful to get permission from the licensed carrier and a license from the FCC to run the Burning Man cell site.
- Normally Bob loses 50% of the bits by not being aligned with Alice.
- Eve loses 50% of the bits by not being aligned with Alice, then
- Bob loses 50% of the bits by not being aligned with Alice, but
- The classical signal from Eve to Bob is strong and does not lose
(a significant number of) bits in the Eve->Bob stretch of fiber.
This (along with other allowances in the system for photon loss
due to the weak single-photon nature of the quantum signal) makes
up for the extra 50% (3dB) loss due to the extra stage of random
choice of polarization alignment.
So the weakness I perceived in the original signal's acceptance of a large amount of loss is actually also cracked by the classical- signal hack of the receiver to NOT trigger on a wrong-orientation signal, rather than being an inherent flaw in the cryptosystem if the detector were operating according to the assumptions.
Have I got that right?
(Also: I take it that having Eve send a handfull of photons trying to make up for the extra 3dB of loss would be detected - when (unlike the hacked classical signal) Bob detected random junk when he and Eve had mismatched polarization?)
Upon further reading I see that the quantum cryptosystems are doing key exchange - so they don't have a shared secret from which to generate a shared idea of which polarization to use when looking. They have to throw away half the bits due to looking wrong and sort it out later.
The flaw is still partly rooted in their excessive redundancy to cover for sufficiently large losses in the data path. But the crack also depends on being able to stimulate "Bob"'s receiver by something that does not correspond to a correctly-polarized copy of Eve's reception of the original signal.
However, one difference betweeen the classical and quantum case is that in the quantum case any possible exploit has to be "online" (i.e. you have to actually intercept the actual sent message and manage to manipulate the receiving system), while for classical key exchange the breaking can also be after the fact (i.e. if all you want is the exchanged information, you can passively record all data and then try to break it afterwards).
But note that these systems only use quantum encryption to perform a key exchange (generation of a shared secret key). The actual data exchanges are then done using the shared session key and ordinary cryptography. Thus the data exchange can be recorded for later attack on the ordinary cryptosystem. The quantum system (provided it is working correctly) just assures that the shared key has to be found by cyphertext analysis and/or guessing, rather than non-real-time compromise of the key exchange itself.
We are not controlling Bob's basis: he chooses his detection basis randomly. What we do is to send a bright-light state that does not cause a detection event if Bob chooses a basis not matching Alice's, but causes a detection event in a specific detector if Bob chooses the same basis as Eve.
So you're actually exploiting the combination TWO flaws:
- One in Bob's detector - which you can get to efficiently mimic the reception you achieved despite your lack of knowledge of Bob's expected polarization.
- One in the protocol - which has so much redundancy attempting to cover for far more than 50% bit loss - and for the receiver's own lack of synchronization with the transmitter's polarization basis selection - that you can discard half the bits due to your own wrong guesses and still echo enough bits to give Bob the information he needs to handshake with Alice and convince the pair of them that things are just fine.
The underlying principle still is valid, those people exploited a technical loophole...
As I recall, the underlying principle of quantum cryptography was that you can't intercept the information in the FIRST PLACE to make a clone of it. These guys intercepted it, cloned the information from it, then made a signal that fooled the receiving detector.
The idea was that your signal either encoded a bit on a single photon as 0/90 degrees or +-45 degrees. The receiver had to know (from a previously distributed symmetric key and some additional synchronizing info which might be photonically transmitted) whether to route the photon to a detector that looked for one modulation or the other - because looking with the wrong kind of detector produces a random number rather than recovering the information. You can cover for some bit lossage by sending data redundantly. But you can't send it SO redundantly that it can be decoded without advance knowledge of how to look.
So the fact that "Eve" was able to fool the receiver with incoherent light pulses tells me these so-called quantum crypto systems are either doing SOMETHING ELSE or sending the information so redundantly that it can be recovered without the knowledge of what angles to use to look at it.
I don't know who wrote TrueType but MS using FreeType must burn them up. I know it would tick me off.
Did they REPLACE FreeType with TrueType? Or did they throw in FreeType, or a piece of it, as an additional kitchen-sink or for some particular function?
All I see, kicking off this article, is a copyright notice as required when some code from FreeType has been included in the product. Where's the evidence that it replaced TrueType, or even that all of FreeType, rather than some small chunk - say, for importing fonts - is in use?
Real usable 3-d goggles / augmented reality glasses have been possible for a while now. (This might make the "lump" at the side lighter. But it's fine as is.) Main trick is a layers of index-of-refraction-discontinuity hack that lets them pipe an image in from the side via total internal reflection, then "reflect" it so the light is coming from a virtual image far in front of the viewer.
Company in Israel makes 'em and I've played with a prototype they supplied to NASA. Sweet. I want!
Unfortunately they haven't gone to production, due to some side-effect of the political/war situation over there. (I think it was that too many of their people got drafted over that Palestinian action a couple years ago.)
The big deal here is eliminating most of the energy loss in the stages before the liquid crystal rotates the polarization. You have to polarize it and you have to select the color for the pixel.
In an ordinary LCD the light is polarized by throwing away the half of its energy that was at the wrong angle - then each pixel's color is selected by throwing away the light that's at the wrong color. It throws away (far more than) 83% of the light before getting around to modulating what's left.
In this new one the color and polarization are selected by bouncing the rejected photons back into the (very shiny) backlight assembly, so they can bounce around and try again somewhere else. That's a big savings. (Not as good as LED-per-pixel, which only turns electricity into light if you're actually going to try to EMIT the light. But it's getting into the ballpark.)
Shrinking the pixels is a bonus. A very important bonus, since it gives you more resolution and permits things like smaller projectors. But the nearly-lossless filtering is what's enabling.
It's not Slashdot "groupthink" when you really are off-topic.
I agree that an "offtopic" mod would have been fair (provided the parent got one, too. B-) )
Unfortunately, Slashdot sometimes doesn't tell me what the downmod category was - and didn't this time. So, from past experience, I assumed the moderation was more likely to be a politically-motivated attempt at suppression rather than an honest rating.
I try to keep my "offtopic" posts "insightful" and/or "informative" enough to be worth reading regardless, and the moderators usually agree with my judgement - except for a few that get bent when I refuse to play along with "ding the conservatives".
One of the downsides of the slashdot moderation system is its vulnerability to abuse by dishonest politically-motivated people who happen to have moderation points.
As is typical: A straight (and not {deliberately} biased) response to a cheap shot from the left wing gets dinged by a (no doubt) left-wing moderator.
- The cultural/political/ideological orientation of much of the population of the United States falls into one of two major groupings. (They tend to be called things like "liberal" and "conservative", "left" and "right", or other pairs of names. But they're each coalitions of many subgroups bound by rough agreement on a few major points.)
- The broadcast news media became sufficiently (and visibly) biased in its programming that the members of one of the groupings felt that they were not being served by it. This created a market opportunity. (This was similar to the one that spawned CNN, when mainstream news migrated from news reportage to infotainment-product generation.)
- Fox News marketed itself as providing "fair and balanced" coverage - half from the viewpoint of each of the two groupings. This made them the only show in town for the one that felt underserved. Thus they grabbed the eyballs of about half the population's newswatchers to sell to their advertisers.
- This worked until about the 2008 campaign, when it became clear that Fox News was serving only one (Neocon) of the four-or-so major and several minor factions within the underserved group. This left several large (and moneyed) factions feeling underserved again and created another marketing opportunity.
- Fox News is going after the biggest coalition of the remaining factions (libertarians + paleoconservatives + {"Tea Party" minus neocons}) with new shows on their "Fox Financial Network" feed.
TV news is easy to understand once you get that it has two purposes:
1) Making money by selling eyeball time to advertisers.
2) Exercising political power by inserting itself between the people in office and the rest of the world and creating a false image of the constituents' opinions and world events for the office-holders.
It was a patent troll that shot down this technology.
I wonder if patent expiration might have been involved, too. The project started 24 years ago. Perhaps, after all the delays, all the fundamental patents would be toast by the time production ramped. So the PHBs might think that even if they got it competitive now they'd be vulnerable to instant generic clones.
Does anyone have any information on how SED could have been even slightly better?
High acceleration voltage to produce secondary electrons up the column. Per-pixel logic. via multiple control elements or even discrete SCEE-based vacuum amplifiers. (Don't recall if those were built in already.)
Of course the former isn't necessary with (O)LED-based screens and the latter can be done with the same semiconductor technology at a more convenient voltage. LEDs can be fantastically efficient and work at low voltages, so electron-bombarded phosphors in a vacuum have a problem.
Pity, though. I've been wishing these puppies would come to market too, for a long time. Phosphor and vacuum have a long life and flurescent die is inherently flirting with its own destruction. So if there isn't a lifetime issue with the emitters (say, positive ion bombardment) these had the potential for far better long-term reliability.
Also: I was hoping SCEE could lead to a renaissance of vacuum tube technology - at integration scales approaching those of semiconductors and inherently high speed and easy scaling for power. There's some stuff that vacuum tech STILL does better than semiconductors, while eliminating the heater power and scaling down to where semiconductor-style voltages would do the actual job could enable still more.
Think of the potential reliability of a purely glass-and-metal structure in a hard vacuum...
For starters, your power is not limited to your own input. You're using a nonlinear process (in this case, parametric amplification) to modulate power obtained from other sources (the solar bombardment of the Earth with charged particles).
Well, yes. I've studied amplification effects, and while they are non-linear, the most we've ever recorded is about 30dB. This was using the Siple transmitter in Antarctica,...
But 30 dB is a LOT. That's a 1,000x on your radiated power. Applying that gain to HAARP you're talking 4 GIGAwatts of energy in the sky from your 10 Megawatts generated, 4 Megawatts radiated.
Once we got to a certain amplification level, the signals would always break down, possibly because the cyclotron resonance breaks down above a certain power level. But nobody really knows, triggered emissions and amplification are some of the least well understood natural phenomena out there.
Or maybe to a certain power level, in which case 4gW might be a tad high. But as you say, "nobody really knows" why you're currently hitting a wall. So perhaps a bit of research will get you past it to additional factors of ten.
Then weather is a chaotic system with lots of gain of its own. A hypothetical weather modification system wouldn't depend on your input power to literally make the weather modifications from scratch, using your sky-power to boil the water for the storms, or even do a big one-shot with a continuing effect, like the "global warming from greenhouse gases increasing solar heat absorption". We'd be talking making some subtle change with vastly amplified consequences a few days later. (And a few GW makes a very big "butterfly's wing".)
I guess what I'm trying to say is that the HAARP theories are like any good conspiracy theory; they start out with a modicum of truth, and then expand it with unproven, unscientific conjecture. So you start with something possible (heating the electrojet with microwaves, or demolishing a building with explosives) and reach something completely impractical, and essentially impossible (Control of weather, gigantic perfectly executed government plan to destroy the WTC).
Sure! And what we're doing here is looking at hypothetical mechanisms for such a technology, just for fun.
As far as gigantic conspiracies to design and use secret weapon technology, the main argument against any particular one of them is that, even if the technology worked, it would be run by a government bureau with its usual level of efficiency and information security. (Look at their handling of the recent economic and oil-spill issues for samples.) B-)
(But government is BUILT out of conspiracies. You just don't find out about most of them until decades later, if at all. Any bets on whether they'd try a weather or earthquake weapon if they thought it would work and they could keep it quiet? B-) Meanwhile, the agencies charged with keeping things secret love to spread nutty sounding stories to discredit everyone who talks about ANY conspiracy. {Consider the technique of "second cover": Plant evidence for a plausible first false explanation for a secret project and also plant evidence for a loony second explanation. Then watch the fun when somebody penetrates to the second cover.})
Such low frequencies penetrate the Earth's surface to considerable depth.
Not if you're talking about EM waves. If we go by the standard model which treats the Earth-Ionosphere cavity as a waveguide, the Earth is essentially an excellent conductor. And the skin depth of a good conductor is essentially zero in terms of geological scales.
Skin depth, even in a good conductor, is still in terms of conductivity and wavelength. Single-digit Hz has a very long wavelength, and we're talking about vertical penetration. Also: The conductivity of the Earth is patchy and largely dependent on water in the region near the surface. Conductive patches between resistive patches could car
This sounds like a good reason to stop releasing all of those convicted murderers and rapists who were freed on DNA evidence.
Not at all.
There is no problem determining that the DNA is from somebody else than the accused. All it takes is a single marker that's different. That's easy.
The problem is going from some bunch of markers that match to saying "This IS the bum! (Well, except for a one-in-[some number] chance it really isn't.) That requires a lot of information about prevalence of genetic markers, whether there is a correlation between their distribution. That information isn't well researched and the different estimates are based on different wild guesses by different experts. Further, the whole independent-probability thing gets knocked into a cocked hat with FAR lower numbers if the police found the accused by searching a DNA database for matches. And what if he had an evil identical twin? Or somebody with access to PCR gene-amplification materials, a DNA sample, and an atomizer decided to frame him?
IMHO DNA evidence is decisive for the defense. But pending a lot more research it's still voodoo for the prosecution.
Make that "Not as far as we know." and I'll agree with you. Or "Not that was detected and publicized."
I hear the security community on the Windows side of the world is of the opinion that it takes a couple years for an exploit to trickle down to where the signature-based antimalware people find out about it.
- First it gets used for spearphishing some high-value target - typically for whomever commissioned its creation.
- Once that customer has gotten his data (or performed his attack), its author gets more money from it by selling it to his five or so top-tier regular customers.
- Repeat for lower tier customers until interest is exhausted or it gets detected (often enough) and the defenders start to become aware of it. Then:
- Wring the last money out of it by selling it broadly to the driftnet malware users, who get a phishing season until signatures are written and propagate to the security vendors' clients. (Once it hits general availability it will immediately hit some honeypots, so if the defenders weren't aware at the previous stage they are now.)
I don't see any reason why an exploit of a broad vulnerability in *x systems running X.org servers should not have a similar latency in detection. (Perhaps longer, since some of the targets are higher value and harder to break into, so the payoff for maintaining stealth could be higher.)
With the switch to kernel modesetting (already happening) there shouldn't be any need for X to mess directly with hardware anymore, and without that it should run just fine without root privileges.
But that just means the X server will be running as something other than root. Doesn't fix the basic problem - which is that any client can use the X server bug to gain the privilege of the X server's account.
If the X server is running as the same account as the client it's not such a big deal. But even if the server is running as the user who is working with the desktop, the client might be something that the user wanted to sandbox into some other account (or otherwise restrict its access, i.e. by limits, chroot,...). This means it can still break out and corrupt his stuff by seizing the X server's privileges.
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"Why," you may ask, "was the internal wiring so insanely packed?" The length of each point-to-point wire was individually calibrated, such that all the signals to each gate arrived [after a known amount of time delay] ...
Cray did this from his earliest designs for Control Data.
His first machines were the CDC 160 (a low-power I/O processor) followed by the CDC 1604 (his first "mainframe"). I "cut my hacker teeth" on a 1604-B, serial number 6.
That was a 48-bit machine (with two instructions per word to save fetch time - he was already thinking speed and inventing RISC).
- The box was in the form of eight swing-out doors, two wide x two front/two back, with the hinges in the middle and the interconnects between the doors in the form of flexible (round) cables plugged into sockets along the hinge-side of each door.
- Each door was a six-bit slice of the ALU plus a share of the instruction sequencer. It had a little power supply in each corner (fed 3-phase 400 Hz power so the transformers were small), six bits of core memory in the center (arranged in even/odd banks so memory access and computation could overlap). The rest of the door was rows of 15-pin card sockets for these little playing-card sized logic cards using discrete components - resistors, diodes, transistors, capacitors. (ICs were available. But Cray used discrete transistors because they were faster.) The cards around the core planes were the memory control, the cards around that were the ALU slice, and the bottom two rows were the instruction sequencer.
The card-side was out on the outer doors and in on the inner - cooling air went up shafts in the center and on just under the outside covers of the unit. The backside of each circuit door, under a door-sized sheetmetal removable cover, was a rats-nest of wires. These were color coded by length and ended in "taper pins". The top three pins of each card were ground and two power inputs, the rest were logic levels. Each pin in the socket had two taper-pin sockets on the back, so two wires could connect to it...
Excluding some special cards the bulk of the cards implemented logic functions using diode-diode-transistor logic. Several multi-input AND gates feeding a multi-input OR gate feeding an inverter transistor. But the way this was arranged was particularly cute: The interconnects were NOT the output of the inverters. They were the summing junction of the and gates.
Each inverter transistor's collector fed several output pins through the diodes of the next stages' AND gates. Wires were daisy-chained from one output to another across all the inverters that drove a given AND term, and also connected to the input pin on the card that finished the and gate. (Think "wired AND".) The input pin on the next stage card had the pullup resistor for the AND gate and a diode to the pulldown resistor for the OR gate and the base of the next stage inverter transistor (along with the far ends of the diodes from the OTHER OR inputs that drove that inverter). There were several card types, with different numbers of inverter transistors, output diodes, and input AND and OR terms.
... nearly as much as I've wondered why the hell [the seats] were there in the first place.
As I recall the Cray was curved with wedge-shaped boards and wiring on the inside of the curve to minimize the length of interconnecting wires and thus maximize logic speed. The outside of the tower was for access to the cards. And that meant the power supplies, cooling plumbing, and other support miscellany had to go somewhere else. "Somewhere else" was further out and at floor level - to be out of the way of access to the cards, which means under the "seats".
Given that people would sit on them (or kneel on them to get to the cards when doing maintenance) anyhow, I'd ASSUME they were padded to avoid injury - making them look like bench seats, but not necessarily be comfortable when used as such.
= = = =
I hear the cooling system had an open space just big enough to hold a six-pack. And the amount of time it took to diagnose, gracefully shutdown and cool down, swap in a replacement board, power up, bring to stable temperature, and run diagnostics, was about the time it took to cool the six-pack to ideal temperature for a "Miller Time" moment when the job was done.
And I hear Cray claimed that this was completely coincidental, rather than a design feature. B-)
"Why," you may ask, "was the internal wiring so insanely packed?" The length of each point-to-point wire was individually calibrated, such that all the signals to each gate arrived at the same moment, so you didn't need flip-flops to latch values in the flow of the circuits.
Deskewing the signals didn't eliminate the need to flop the levels - by a long shot.
What it's about is arranging the placement of gates and routing of signals so you avoid situations where most of the inputs to a logic function have arrived but there's one that's taking a long time - so your output isn't right for a considerable time after the inputs change. By getting everything together at the same time you eliminate the long run and get the answer sooner. This lets you have more layers of random logic between the layers of latches, which gets more steps of computing done between ticks of the clock.
These days it's done on chips by the "place and route" tools. Back then the machines were simple enough that it could be done by some smart engineers thinking hard - and techies hooking up the interconnections with wires color-coded by LENGTH, rather than by what signal they carry.
That is an interesting narative. I'm amazed that the investigators were able to obtain temperature records that the CRU admits that they lost. Or I should say, admitted they lost after numerous FOI requests.
Additionally, there's a difference between allegedly "being able to obtain them in three days" and obtaining them with a traceable chain of custody and records allowing them to be rated for accuracy and completeness, making them a suitable foundation for analysis to support or refute - and possibly extend - the original scientists' work.
It often strikes me as an interesting thing that we have no social mechanism for turning down a technical capability, even when we largely believe it's a bad idea.
Sure we have mechanisms for turning down a technical capability.
It's called "personal choice".
\
Freedom means each person gets to make that choice for his/her SELF.
"Social Mechanism?" You mean "way for a group to impose its choices on those who disagree with them", don't you?
The closest you have in a free society is persuasion. And others get to argue the other way, or just ignore you. When persuasion becomes social pressure to conform, freedom is replaced by groupthink.
Ummm, I'm confused. The frequencies that GSM uses are licensed by the FCC to specific operators. The phones are used under the control of the operator, who has a license for each and every cell site.
This group, (The OpenBTS project) has permission from the carrier with the license for the area (who doesn't happen to have a cell covering the site) to use the band there.
Additionally (as others have pointed out), they have a specific short-term ("experimental") license to perform this test during the period including the festival and the runup to it. This license includes the right to stimulate the cellphones into operation.
The group also provides emergency service to disasters that have taken out the cellular infrastructure, until the carriers can get it back up, and makes low-cost base station equipment designs (using off-the-shelf hardware) available to third-world countries. ($10k and dropping.) The burning-man event gives them an annual opportunity to do an acid test on their latest software and hardware.
Just what you'd expect: The FCC hunts 'em down and shuts 'em down if they're strong enough to be noticed and especially if they interfere with the license holding service provider for that area and band.
Unlike WiFi, but like broadcast radio, the DSM protocols don't support sharing a given band in a given area. The license holders carefully design their cell site arrangements so their own cells don't step on each other (and nearby neighbors near the edge of their area). If you set up an unlicensed homebrew minicell on band that's in use and don't do it inside a shielded box, you'll trash the licensed service and be in deep kimchi, just as if you wiped out a broadcast station with your pirate radio.
Which is why the OpenBTS project was careful to get permission from the licensed carrier and a license from the FCC to run the Burning Man cell site.
Thanks. (I figured that out after posting. B-b ).
If I've got it correctly:
- Normally Bob loses 50% of the bits by not being aligned with Alice.
- Eve loses 50% of the bits by not being aligned with Alice, then
- Bob loses 50% of the bits by not being aligned with Alice, but
- The classical signal from Eve to Bob is strong and does not lose
(a significant number of) bits in the Eve->Bob stretch of fiber.
This (along with other allowances in the system for photon loss
due to the weak single-photon nature of the quantum signal) makes
up for the extra 50% (3dB) loss due to the extra stage of random
choice of polarization alignment.
So the weakness I perceived in the original signal's acceptance of
a large amount of loss is actually also cracked by the classical-
signal hack of the receiver to NOT trigger on a wrong-orientation
signal, rather than being an inherent flaw in the cryptosystem
if the detector were operating according to the assumptions.
Have I got that right?
(Also: I take it that having Eve send a handfull of photons
trying to make up for the extra 3dB of loss would be detected -
when (unlike the hacked classical signal) Bob detected random
junk when he and Eve had mismatched polarization?)
Upon further reading I see that the quantum cryptosystems are doing key exchange - so they don't have a shared secret from which to generate a shared idea of which polarization to use when looking. They have to throw away half the bits due to looking wrong and sort it out later.
The flaw is still partly rooted in their excessive redundancy to cover for sufficiently large losses in the data path. But the crack also depends on being able to stimulate "Bob"'s receiver by something that does not correspond to a correctly-polarized copy of Eve's reception of the original signal.
However, one difference betweeen the classical and quantum case is that in the quantum case any possible exploit has to be "online" (i.e. you have to actually intercept the actual sent message and manage to manipulate the receiving system), while for classical key exchange the breaking can also be after the fact (i.e. if all you want is the exchanged information, you can passively record all data and then try to break it afterwards).
But note that these systems only use quantum encryption to perform a key exchange (generation of a shared secret key). The actual data exchanges are then done using the shared session key and ordinary cryptography. Thus the data exchange can be recorded for later attack on the ordinary cryptosystem. The quantum system (provided it is working correctly) just assures that the shared key has to be found by cyphertext analysis and/or guessing, rather than non-real-time compromise of the key exchange itself.
We are not controlling Bob's basis: he chooses his detection basis randomly. What we do is to send a bright-light state that does not cause a detection event if Bob chooses a basis not matching Alice's, but causes a detection event in a specific detector if Bob chooses the same basis as Eve.
So you're actually exploiting the combination TWO flaws:
- One in Bob's detector - which you can get to efficiently mimic the reception you achieved despite your lack of knowledge of Bob's expected polarization.
- One in the protocol - which has so much redundancy attempting to cover for far more than 50% bit loss - and for the receiver's own lack of synchronization with the transmitter's polarization basis selection - that you can discard half the bits due to your own wrong guesses and still echo enough bits to give Bob the information he needs to handshake with Alice and convince the pair of them that things are just fine.
The underlying principle still is valid, those people exploited a technical loophole ...
As I recall, the underlying principle of quantum cryptography was that you can't intercept the information in the FIRST PLACE to make a clone of it. These guys intercepted it, cloned the information from it, then made a signal that fooled the receiving detector.
The idea was that your signal either encoded a bit on a single photon as 0/90 degrees or +-45 degrees. The receiver had to know (from a previously distributed symmetric key and some additional synchronizing info which might be photonically transmitted) whether to route the photon to a detector that looked for one modulation or the other - because looking with the wrong kind of detector produces a random number rather than recovering the information. You can cover for some bit lossage by sending data redundantly. But you can't send it SO redundantly that it can be decoded without advance knowledge of how to look.
So the fact that "Eve" was able to fool the receiver with incoherent light pulses tells me these so-called quantum crypto systems are either doing SOMETHING ELSE or sending the information so redundantly that it can be recovered without the knowledge of what angles to use to look at it.
I don't know who wrote TrueType but MS using FreeType must burn them up. I know it would tick me off.
Did they REPLACE FreeType with TrueType? Or did they throw in FreeType, or a piece of it, as an additional kitchen-sink or for some particular function?
All I see, kicking off this article, is a copyright notice as required when some code from FreeType has been included in the product. Where's the evidence that it replaced TrueType, or even that all of FreeType, rather than some small chunk - say, for importing fonts - is in use?
Real usable 3-d goggles / augmented reality glasses have been possible for a while now. (This might make the "lump" at the side lighter. But it's fine as is.) Main trick is a layers of index-of-refraction-discontinuity hack that lets them pipe an image in from the side via total internal reflection, then "reflect" it so the light is coming from a virtual image far in front of the viewer.
Company in Israel makes 'em and I've played with a prototype they supplied to NASA. Sweet. I want!
Unfortunately they haven't gone to production, due to some side-effect of the political/war situation over there. (I think it was that too many of their people got drafted over that Palestinian action a couple years ago.)
... the Toilet of Power!
The big deal here is eliminating most of the energy loss in the stages before the liquid crystal rotates the polarization. You have to polarize it and you have to select the color for the pixel.
In an ordinary LCD the light is polarized by throwing away the half of its energy that was at the wrong angle - then each pixel's color is selected by throwing away the light that's at the wrong color. It throws away (far more than) 83% of the light before getting around to modulating what's left.
In this new one the color and polarization are selected by bouncing the rejected photons back into the (very shiny) backlight assembly, so they can bounce around and try again somewhere else. That's a big savings. (Not as good as LED-per-pixel, which only turns electricity into light if you're actually going to try to EMIT the light. But it's getting into the ballpark.)
Shrinking the pixels is a bonus. A very important bonus, since it gives you more resolution and permits things like smaller projectors. But the nearly-lossless filtering is what's enabling.
It's not Slashdot "groupthink" when you really are off-topic.
I agree that an "offtopic" mod would have been fair (provided the parent got one, too. B-) )
Unfortunately, Slashdot sometimes doesn't tell me what the downmod category was - and didn't this time. So, from past experience, I assumed the moderation was more likely to be a politically-motivated attempt at suppression rather than an honest rating.
I try to keep my "offtopic" posts "insightful" and/or "informative" enough to be worth reading regardless, and the moderators usually agree with my judgement - except for a few that get bent when I refuse to play along with "ding the conservatives".
One of the downsides of the slashdot moderation system is its vulnerability to abuse by dishonest politically-motivated people who happen to have moderation points.
As is typical: A straight (and not {deliberately} biased) response to a cheap shot from the left wing gets dinged by a (no doubt) left-wing moderator.
But feel free to ding this one, too. B-)
Nobody can explain Fox News either.
Sure they can.
- The cultural/political/ideological orientation of much of the population of the United States falls into one of two major groupings. (They tend to be called things like "liberal" and "conservative", "left" and "right", or other pairs of names. But they're each coalitions of many subgroups bound by rough agreement on a few major points.)
- The broadcast news media became sufficiently (and visibly) biased in its programming that the members of one of the groupings felt that they were not being served by it. This created a market opportunity. (This was similar to the one that spawned CNN, when mainstream news migrated from news reportage to infotainment-product generation.)
- Fox News marketed itself as providing "fair and balanced" coverage - half from the viewpoint of each of the two groupings. This made them the only show in town for the one that felt underserved. Thus they grabbed the eyballs of about half the population's newswatchers to sell to their advertisers.
- This worked until about the 2008 campaign, when it became clear that Fox News was serving only one (Neocon) of the four-or-so major and several minor factions within the underserved group. This left several large (and moneyed) factions feeling underserved again and created another marketing opportunity.
- Fox News is going after the biggest coalition of the remaining factions (libertarians + paleoconservatives + {"Tea Party" minus neocons}) with new shows on their "Fox Financial Network" feed.
TV news is easy to understand once you get that it has two purposes:
1) Making money by selling eyeball time to advertisers.
2) Exercising political power by inserting itself between the people in office and the rest of the world and creating a false image of the constituents' opinions and world events for the office-holders.
It was a patent troll that shot down this technology.
I wonder if patent expiration might have been involved, too. The project started 24 years ago. Perhaps, after all the delays, all the fundamental patents would be toast by the time production ramped. So the PHBs might think that even if they got it competitive now they'd be vulnerable to instant generic clones.
Does anyone have any information on how SED could have been even slightly better?
High acceleration voltage to produce secondary electrons up the column. Per-pixel logic. via multiple control elements or even discrete SCEE-based vacuum amplifiers. (Don't recall if those were built in already.)
Of course the former isn't necessary with (O)LED-based screens and the latter can be done with the same semiconductor technology at a more convenient voltage. LEDs can be fantastically efficient and work at low voltages, so electron-bombarded phosphors in a vacuum have a problem.
Pity, though. I've been wishing these puppies would come to market too, for a long time. Phosphor and vacuum have a long life and flurescent die is inherently flirting with its own destruction. So if there isn't a lifetime issue with the emitters (say, positive ion bombardment) these had the potential for far better long-term reliability.
Also: I was hoping SCEE could lead to a renaissance of vacuum tube technology - at integration scales approaching those of semiconductors and inherently high speed and easy scaling for power. There's some stuff that vacuum tech STILL does better than semiconductors, while eliminating the heater power and scaling down to where semiconductor-style voltages would do the actual job could enable still more.
Think of the potential reliability of a purely glass-and-metal structure in a hard vacuum...
For starters, your power is not limited to your own input. You're using a nonlinear process (in this case, parametric amplification) to modulate power obtained from other sources (the solar bombardment of the Earth with charged particles).
Well, yes. I've studied amplification effects, and while they are non-linear, the most we've ever recorded is about 30dB. This was using the Siple transmitter in Antarctica, ...
But 30 dB is a LOT. That's a 1,000x on your radiated power. Applying that gain to HAARP you're talking 4 GIGAwatts of energy in the sky from your 10 Megawatts generated, 4 Megawatts radiated.
Once we got to a certain amplification level, the signals would always break down, possibly because the cyclotron resonance breaks down above a certain power level. But nobody really knows, triggered emissions and amplification are some of the least well understood natural phenomena out there.
Or maybe to a certain power level, in which case 4gW might be a tad high. But as you say, "nobody really knows" why you're currently hitting a wall. So perhaps a bit of research will get you past it to additional factors of ten.
Then weather is a chaotic system with lots of gain of its own. A hypothetical weather modification system wouldn't depend on your input power to literally make the weather modifications from scratch, using your sky-power to boil the water for the storms, or even do a big one-shot with a continuing effect, like the "global warming from greenhouse gases increasing solar heat absorption". We'd be talking making some subtle change with vastly amplified consequences a few days later. (And a few GW makes a very big "butterfly's wing".)
I guess what I'm trying to say is that the HAARP theories are like any good conspiracy theory; they start out with a modicum of truth, and then expand it with unproven, unscientific conjecture. So you start with something possible (heating the electrojet with microwaves, or demolishing a building with explosives) and reach something completely impractical, and essentially impossible (Control of weather, gigantic perfectly executed government plan to destroy the WTC).
Sure! And what we're doing here is looking at hypothetical mechanisms for such a technology, just for fun.
As far as gigantic conspiracies to design and use secret weapon technology, the main argument against any particular one of them is that, even if the technology worked, it would be run by a government bureau with its usual level of efficiency and information security. (Look at their handling of the recent economic and oil-spill issues for samples.) B-)
(But government is BUILT out of conspiracies. You just don't find out about most of them until decades later, if at all. Any bets on whether they'd try a weather or earthquake weapon if they thought it would work and they could keep it quiet? B-) Meanwhile, the agencies charged with keeping things secret love to spread nutty sounding stories to discredit everyone who talks about ANY conspiracy. {Consider the technique of "second cover": Plant evidence for a plausible first false explanation for a secret project and also plant evidence for a loony second explanation. Then watch the fun when somebody penetrates to the second cover.})
Such low frequencies penetrate the Earth's surface to considerable depth.
Not if you're talking about EM waves. If we go by the standard model which treats the Earth-Ionosphere cavity as a waveguide, the Earth is essentially an excellent conductor. And the skin depth of a good conductor is essentially zero in terms of geological scales.
Skin depth, even in a good conductor, is still in terms of conductivity and wavelength. Single-digit Hz has a very long wavelength, and we're talking about vertical penetration. Also: The conductivity of the Earth is patchy and largely dependent on water in the region near the surface. Conductive patches between resistive patches could car
This sounds like a good reason to stop releasing all of those convicted murderers and rapists who were freed on DNA evidence.
Not at all.
There is no problem determining that the DNA is from somebody else than the accused. All it takes is a single marker that's different. That's easy.
The problem is going from some bunch of markers that match to saying "This IS the bum! (Well, except for a one-in-[some number] chance it really isn't.) That requires a lot of information about prevalence of genetic markers, whether there is a correlation between their distribution. That information isn't well researched and the different estimates are based on different wild guesses by different experts. Further, the whole independent-probability thing gets knocked into a cocked hat with FAR lower numbers if the police found the accused by searching a DNA database for matches. And what if he had an evil identical twin? Or somebody with access to PCR gene-amplification materials, a DNA sample, and an atomizer decided to frame him?
IMHO DNA evidence is decisive for the defense. But pending a lot more research it's still voodoo for the prosecution.
Was there an actual attack? No.
Make that "Not as far as we know." and I'll agree with you. Or "Not that was detected and publicized."
I hear the security community on the Windows side of the world is of the opinion that it takes a couple years for an exploit to trickle down to where the signature-based antimalware people find out about it.
- First it gets used for spearphishing some high-value target - typically for whomever commissioned its creation.
- Once that customer has gotten his data (or performed his attack), its author gets more money from it by selling it to his five or so top-tier regular customers.
- Repeat for lower tier customers until interest is exhausted or it gets detected (often enough) and the defenders start to become aware of it. Then:
- Wring the last money out of it by selling it broadly to the driftnet malware users, who get a phishing season until signatures are written and propagate to the security vendors' clients. (Once it hits general availability it will immediately hit some honeypots, so if the defenders weren't aware at the previous stage they are now.)
I don't see any reason why an exploit of a broad vulnerability in *x systems running X.org servers should not have a similar latency in detection. (Perhaps longer, since some of the targets are higher value and harder to break into, so the payoff for maintaining stealth could be higher.)
With the switch to kernel modesetting (already happening) there shouldn't be any need for X to mess directly with hardware anymore, and without that it should run just fine without root privileges.
But that just means the X server will be running as something other than root. Doesn't fix the basic problem - which is that any client can use the X server bug to gain the privilege of the X server's account.
If the X server is running as the same account as the client it's not such a big deal. But even if the server is running as the user who is working with the desktop, the client might be something that the user wanted to sandbox into some other account (or otherwise restrict its access, i.e. by limits, chroot, ...). This means it can still break out and corrupt his stuff by seizing the X server's privileges.
This is seriously fishy. At a price of $3/galon ...
Yo, Dude! HAARP is in ALASKA! Fuel is a tad pricier there.