Ethernet carries packet-based protocols which have error correction. If one packet corrupts, no problem. HDMI is a constant stream, so any glitches will show up on your TV.
It's not accurate to say that bandwidths aren't measured in Hertz. After all, w = 2*pi*f.
I'm not sure what you mean by "the transmitted audio signal is not digital". If anything, digital signals need wider bandwidth than the baud rate. See Howard Johnson's "Black Magic" books. Losing harmonics means losing eye quality, to a certain extent.
My comment was meant to be a general comparison of engineering complexity. An accurate analysis is not worth doing for/. purposes. When you work at a few GHz, you tend to think of anything below a MHz as "easy" (which it is). That's the take-home message.
Ah neat, eye diagrams. People like to say that high-speed digital design is really analog design. It's quite true. What matters here is the cable loss and dispersion, which will be finite for anything except a perfect transmission line. Better cable = better transmission line.
To relate this to the topic, consider that HDMI cables need bandwidth of over 3 GHZ (cat 2), while audio signals only go to 20 kHz. Even if we generously extend the audio bandwidth to 100KHz, there's over 4 orders of magnitude difference. So it's not surprising that a cable for gigabit speeds needs tighter specs.
Thanks for the thoughtful response. I don't agree with some of your points, but I'll admit I don't have much background in this area. Any recommended reading?
Factually, there is no physical evidence proving creation or evolution; it all boils down to an issue of faith.
I've heard this argument from my Christian friends, that at the bottom of rational thought lies some faith, but it's really messy, slippery-slope argument. Pretty soon you invoke Nietzsche, and then ultimately, Hume.
Then the evolution/creation/ID argument, which has been framed in a rather calculated fashion to blur the lines between faith and reason. I cringe when people say, "do you believe in evolution"? There is literally megatons of physical evidence backing up the theory, and to deny that is absolutely irrational. Evolution is a rational argument that can be proven or disproven. So is general relativity. But Genesis can't be proven or disproven (not to mention reconciling its two conflicting accounts).
My friend who went to a Christian college told me about a course he took which made the case for a scientifically justified belief in Christianity. I read one of the course books, and it was really just apologetics with some historical bent.
No body can choose for you, inevitably you make your own choice, but calling people, who don't think like you, idiots, just goes back to the thread parent's argument that when people's core beliefs are questioned, they become irrational.
The parent didn't use any epithets. Rather, he put out a rational argument and got a reply mostly arguing from Scripture or dogma. That should tell you something.
$7 sounds pretty good to me. I hate the RIAA labels but $7 is a price I can't argue with -- it's reasonable. I especially dislike Warner, which has a stranglehold on the Columbia and Atlantic jazz catalogs.
It's hard to find jazz albums for $7 used, let alone new, so I'll take this opportunity to patch holes in my collection. Having the tracks stream-able is a neat bonus, even if I don't see myself using it often.
I'm talking about existing/realistic parts. Certainly you can put everything on a bus. That's obvious. But a bus within an MCP? I doubt that Hynix would go through all the effort to create what amounts to a memory controller when they can just add a mux to the existing logic.
Flash chips have a standard interface: a set of control lines and an 8 or 16 bit address/data bus. In multichip flash packages, each chip is typically mapped to a portion of the address space. This also allows backwards compatibility when the die density eventually doubles. (e.g. I was using some Micron parts where the 4Gb part was a 2x 2Gb MCP. A couple months later and the chip was revised to 1x 4Gb.)
If you want parallel read, you're going to need a whole lotta pins, and corresponding board area. Whereas the point of the MCP is to reduce pin count and board area. MCPs are for highly integrated devices like cellphones and portable media players, where space is at a premium. The throughput of one Flash chip is sufficient for these applications.
The boards contain 15 Virtex-II Pro (XC2VP20) FPGAs in 3 identical sets of 5 (here called "channels"). Each channel also owns a Spartan-II (XC2S50) FPGA that was originally used as a control chip, and a DSP (ADSP21160M) which probably calculated transform parameters. There is also a shared XC2S50 chip, which is not used in this application, just like the DSPs. The clock distribution tree unfortunately contains 2 domains, which means the 39MHz channel clock had to be distributed from chip to chip, using internal Virtex-II DCMs to clean it up.
To control the boards, an USB boardlet has been built and the Spartan-II chips programmed to share the USB interface using a ring protocol. Spartan-II chips translate USB-carried command packets into bus transactions (16-bit address, 18-bit data) and the bus read data into USB packets again. They also service SHA1 breaker IRQs to minimize the number of results that had to be merged into one - there is a buffer for 1024 18-bit reads in each Spartan-II.
This is a really neat project. These FPGAs aren't the latest and greatest, but when you've got 15 of them, parallelism is your friend.
Outside of my job, I've had some ideas for FPGA projects, but the (mostly) BGA packages result in very expensive multilayer boards; too expensive for hobbyist purposes. You'd also have to contract out the BGA assembly, and depending on the FPGA chosen, spend a lot on the FPGA itself. (The smaller FPGAs are available in hand-solderable flat-packs, but the logic densities are typically insufficient. At least we can get small FPGAs from Digikey for $10 and up.) An obvious workaround is to buy a dev board, but they're still relatively expensive, and you've got IO hardwired to the various peripherals they stick on the dev board.
This SHA-1 project cleverly reuses hardware that someone else devoted a lot of time and money to./me wonders where he can get hardware like this on the cheap...
Fusion in storm clouds would produce fast neutrons, which have a very low probability of colliding with anything. Their mean free path in normal atmosphere is huge. You wouldn't expect to be able to localize them (or their products) to a single thundercloud/storm, given the small numbers produced.
I also skated through high school and ended up skating through college. While I didn't fail any classes, I never developed the work ethic to get those 'A's. Now I want to go to grad school, but it looks difficult to get into a top-tier program with average grades.
He3+He3 fusion on Earth, seriously? I don't think that's a realistic fuel; the reaction cross-section is extremely small, even at solar temperatures. Nobody talks about doing He3+He3 fusion. Are you perhaps thinking about D+He3 fusion?
D+He3 fusion (and other aneutronic fusion, like p+B11) certainly is nice, but we're not going to get there anytime soon. Why? These fuels don't "burn" easily; the cross-sections for aneutronic fuels are lower than DT's, and peak at substantially higher temperatures. I suspect we won't be able to do aneutronic fusion until we master DT fusion.
Regarding your scheme for producing He3, DT fusion reactor designs envision a "lithium blanket" where tritium will be bred by the neutron flux. Perhaps someday DT reactors will supply the fuel for D+He3 ones.
We're not reinventing the wheel. The sun's fusion reactions are very different from the ones envisioned for terrestrial fusion reactors.
The sun starts by fusing hydrogen. (http://www.tim-thompson.com/fusion.html) This first step happens on a huge timescale:
p + p --> d + e+ + nu 7.9 x 10^9 years
This only works out in the sun because it's a frickin huge ball of gas.
Terrestrial reactors will use DT fusion. The time it takes for this reaction to happen is not worth talking about.
And regarding the "plasma ball with high density", consider that the typical DT fusion plasma has a density of 10^20/m^3, which is one millionth the density of air.
In short, we can do fusion better than nature can. In 50 years (TM), that is.
Actually, the biggest power demand in a Tokamak as I understand is for heating the plasma to a temperature where fusion will take place. The hotter it gets, the faster fusion occurs, eventually reaching a breakeven point energy is released by fusion faster than it is carried away by escaping neutrons and gamma rays. Then the plasma can sustain itself. We haven't gotten there yet. Some subtleties:
Fusion reaction rates are proportional to temperature, but only up to a certain point. The trend is roughly parabolic.
'Breakeven' is usually calculated on the assumption that energy leaving the plasma is reinjected with a certain efficiency, typically 1/3. 'Ignition' is when the fusion reaction can go on without any external power input.
Also, I realize it's a rough analogy, but the dam picture is inadequate. My professor described fusion confinement as "trying to hold jell-o with string".
Most of the major research labs in the US are technically owned by the DOE, whether they're primarily weapons/classified research (Livermore, Los Alamos) or closely linked to academia (Berkeley, Fermilab).
The DOE and the NSF fund various projects (with some subject area overlap) but it's still up to individual scientists to write proposals asking for supercomputer time.
Chill out, man. The Parent didn't have any fanboyism at all, but your post is full of it.
Intel's processors are faster without using more transistors, indications that the architecture is more optimized and makes better use of the available transistors.
The Core2 has almost 2x the transistor count of the Athlon X2, due to the huge cache. Or do you mean logic transistors? I can't find numbers for those. (Not that using more transistors would necessarily speed things up. In pipelining, perhaps, but we see how well that approach worked in the P4. I'd hesitate to pass judgment on an architecture, solely based on its transistor count and clock speed.)
Also consider, the die shrink to 65nm for AMD produced little to no benefits in speed and scalability (read: you couldn't over clock them very much)
It improved power consumption, though. And yields, I'd assume.
Also, if anyone remembers, the Pentium M (which the Core 2 is based off) was benchmarked a few years ago against the AMD 64bit desktop processors and spanked them, no not in all cases or by any significant margin, but the fact a low power laptop processor (32bit) matched a 64bit mid-range/hi-end processor from AMD; that should indicate the advantages of the architecture.
If we're talking about Yonah, it was slightly slower than the X2, clock for clock (which I'd hardly consider a "spanking"). True, Yonah had no on-die memory controller, and had worse cache latency compared to its predecessor, which makes for a pretty impressive showing.
As for the future, it looks like Barcelona will have killer FP, presuming it gets released soon.
Anyway, it's obvious that the Core2's features (4-issue, macro-ops fusion, 1-cycle SSE, etc) provide the current performance leadership on the desktop, but the FSB/memory interface is weak. Which is why Intel is going the same direction AMD has gone in those areas.
Back in the 70s, analyzing Japan's rapid ascent was all the vogue. And when their economy tanked, figuring out the cause was the goal. Upon further examination, rapid-development economies are never completely "western" and free-market -- they depend heavily on government support and guidance. And that includes the United States in a previous century.
China is successful right now, but so are the other "Asian tigers" that followed Japan's model: Taiwan and South Korea.
Well, it's not like we didn't know it existed. This just props up the Standard Model some more.
Though this particle is "only" 6 GeV, it certainly is a rather rare process -- 15 candidates in five years of running. They've probably found far more top quarks. Why is it so rare? My guess is: because it contains a down quark, a bottom quark, and a strange quark, which is a unique and relatively heavy combination.
I wrote: "There are absolutely no citations in the part that talks about solid-state memory (lots of cites in the magnetic part though), so I am skeptical. If it could be done, he could have easily presented proof."
Note that this paper is from 1996, is from a symposium, and deals mainly with magnetic media. There are absolutely no citations in the part that talks about solid-state memory (lots of cites in the magnetic part though), so I am skeptical. If it could be done, he could have easily presented proof.
And now it's been ten years, with device area getting cut in half just about every two years. In modern DRAM, the charge storage is so minute that any accumulated oxide stress effects would be lost in the noise.
Slashdot Mirror
I suspect that cat6 has very good economies of scale in place. Plus the connectors are cheap.
The rest is good vs bad engineering:
http://www.bluejeanscable.com/articles/whats-the-matter-with-hdmi.htm
Ethernet carries packet-based protocols which have error correction. If one packet corrupts, no problem. HDMI is a constant stream, so any glitches will show up on your TV.
It's not accurate to say that bandwidths aren't measured in Hertz. After all, w = 2*pi*f.
/. purposes. When you work at a few GHz, you tend to think of anything below a MHz as "easy" (which it is). That's the take-home message.
I'm not sure what you mean by "the transmitted audio signal is not digital". If anything, digital signals need wider bandwidth than the baud rate. See Howard Johnson's "Black Magic" books. Losing harmonics means losing eye quality, to a certain extent.
My comment was meant to be a general comparison of engineering complexity. An accurate analysis is not worth doing for
Ah neat, eye diagrams. People like to say that high-speed digital design is really analog design. It's quite true. What matters here is the cable loss and dispersion, which will be finite for anything except a perfect transmission line. Better cable = better transmission line.
To relate this to the topic, consider that HDMI cables need bandwidth of over 3 GHZ (cat 2), while audio signals only go to 20 kHz. Even if we generously extend the audio bandwidth to 100KHz, there's over 4 orders of magnitude difference. So it's not surprising that a cable for gigabit speeds needs tighter specs.
Thanks for the thoughtful response. I don't agree with some of your points, but I'll admit I don't have much background in this area. Any recommended reading?
Correction:
%s/proven or disproven/disproved/g
I've heard this argument from my Christian friends, that at the bottom of rational thought lies some faith, but it's really messy, slippery-slope argument. Pretty soon you invoke Nietzsche, and then ultimately, Hume.
Then the evolution/creation/ID argument, which has been framed in a rather calculated fashion to blur the lines between faith and reason. I cringe when people say, "do you believe in evolution"? There is literally megatons of physical evidence backing up the theory, and to deny that is absolutely irrational. Evolution is a rational argument that can be proven or disproven. So is general relativity. But Genesis can't be proven or disproven (not to mention reconciling its two conflicting accounts).
My friend who went to a Christian college told me about a course he took which made the case for a scientifically justified belief in Christianity. I read one of the course books, and it was really just apologetics with some historical bent.
The parent didn't use any epithets. Rather, he put out a rational argument and got a reply mostly arguing from Scripture or dogma. That should tell you something.
The abundance of deuterium in seawater is about 1/6400.
$7 sounds pretty good to me. I hate the RIAA labels but $7 is a price I can't argue with -- it's reasonable.
I especially dislike Warner, which has a stranglehold on the Columbia and Atlantic jazz catalogs.
It's hard to find jazz albums for $7 used, let alone new, so I'll take this opportunity to patch holes in my collection. Having the tracks stream-able is a neat bonus, even if I don't see myself using it often.
GNU Radio is also a good example of the cost downside to SDR. The basic board, the USRP, costs $700. And then you gotta buy daughterboards.
I figure in a few more years we'll get cheap SDR.
Here at work my wuapi.dll is 7.0.6000.381, date July 30. I have automatic updates on, and actively Windows Update-d just yesterday.
When I get home I'll see whether my personal box has anything different. That machine has the Update services disabled (I think; it's a recent build).
I'm talking about existing/realistic parts. Certainly you can put everything on a bus. That's obvious. But a bus within an MCP? I doubt that Hynix would go through all the effort to create what amounts to a memory controller when they can just add a mux to the existing logic.
Flash chips have a standard interface: a set of control lines and an 8 or 16 bit address/data bus. In multichip flash packages, each chip is typically mapped to a portion of the address space. This also allows backwards compatibility when the die density eventually doubles. (e.g. I was using some Micron parts where the 4Gb part was a 2x 2Gb MCP. A couple months later and the chip was revised to 1x 4Gb.)
If you want parallel read, you're going to need a whole lotta pins, and corresponding board area. Whereas the point of the MCP is to reduce pin count and board area. MCPs are for highly integrated devices like cellphones and portable media players, where space is at a premium. The throughput of one Flash chip is sufficient for these applications.
This is a really neat project. These FPGAs aren't the latest and greatest, but when you've got 15 of them, parallelism is your friend.
Outside of my job, I've had some ideas for FPGA projects, but the (mostly) BGA packages result in very expensive multilayer boards; too expensive for hobbyist purposes. You'd also have to contract out the BGA assembly, and depending on the FPGA chosen, spend a lot on the FPGA itself. (The smaller FPGAs are available in hand-solderable flat-packs, but the logic densities are typically insufficient. At least we can get small FPGAs from Digikey for $10 and up.) An obvious workaround is to buy a dev board, but they're still relatively expensive, and you've got IO hardwired to the various peripherals they stick on the dev board.
This SHA-1 project cleverly reuses hardware that someone else devoted a lot of time and money to.
Fusion in storm clouds would produce fast neutrons, which have a very low probability of colliding with anything. Their mean free path in normal atmosphere is huge. You wouldn't expect to be able to localize them (or their products) to a single thundercloud/storm, given the small numbers produced.
I also skated through high school and ended up skating through college. While I didn't fail any classes, I never developed the work ethic to get those 'A's. Now I want to go to grad school, but it looks difficult to get into a top-tier program with average grades.
Did you end up developing a good work ethic?
He3+He3 fusion on Earth, seriously? I don't think that's a realistic fuel; the reaction cross-section is extremely small, even at solar temperatures. Nobody talks about doing He3+He3 fusion. Are you perhaps thinking about D+He3 fusion?
i cs/
D+He3 fusion (and other aneutronic fusion, like p+B11) certainly is nice, but we're not going to get there anytime soon. Why? These fuels don't "burn" easily; the cross-sections for aneutronic fuels are lower than DT's, and peak at substantially higher temperatures. I suspect we won't be able to do aneutronic fusion until we master DT fusion.
See the Fusion FAQ, question H.
http://www.faqs.org/faqs/fusion-faq/section1-phys
Regarding your scheme for producing He3, DT fusion reactor designs envision a "lithium blanket" where tritium will be bred by the neutron flux. Perhaps someday DT reactors will supply the fuel for D+He3 ones.
We're not reinventing the wheel. The sun's fusion reactions are very different from the ones envisioned for terrestrial fusion reactors.
/m^3, which is one millionth the density of air.
The sun starts by fusing hydrogen. (http://www.tim-thompson.com/fusion.html)
This first step happens on a huge timescale:
p + p --> d + e+ + nu 7.9 x 10^9 years
This only works out in the sun because it's a frickin huge ball of gas.
Terrestrial reactors will use DT fusion. The time it takes for this reaction to happen is not worth talking about.
And regarding the "plasma ball with high density", consider that the typical DT fusion plasma has a density of 10^20
In short, we can do fusion better than nature can. In 50 years (TM), that is.
Fusion reaction rates are proportional to temperature, but only up to a certain point. The trend is roughly parabolic.
'Breakeven' is usually calculated on the assumption that energy leaving the plasma is reinjected with a certain efficiency, typically 1/3. 'Ignition' is when the fusion reaction can go on without any external power input.
Also, I realize it's a rough analogy, but the dam picture is inadequate. My professor described fusion confinement as "trying to hold jell-o with string".
Most of the major research labs in the US are technically owned by the DOE, whether they're primarily weapons/classified research (Livermore, Los Alamos) or closely linked to academia (Berkeley, Fermilab).
The DOE and the NSF fund various projects (with some subject area overlap) but it's still up to individual scientists to write proposals asking for supercomputer time.
Putting all the fanboy drivel aside for a moment;
Chill out, man. The Parent didn't have any fanboyism at all, but your post is full of it.
Intel's processors are faster without using more transistors, indications that the architecture is more optimized and makes better use of the available transistors.
The Core2 has almost 2x the transistor count of the Athlon X2, due to the huge cache. Or do you mean logic transistors? I can't find numbers for those. (Not that using more transistors would necessarily speed things up. In pipelining, perhaps, but we see how well that approach worked in the P4. I'd hesitate to pass judgment on an architecture, solely based on its transistor count and clock speed.)
Also consider, the die shrink to 65nm for AMD produced little to no benefits in speed and scalability (read: you couldn't over clock them very much)
It improved power consumption, though. And yields, I'd assume.
Also, if anyone remembers, the Pentium M (which the Core 2 is based off) was benchmarked a few years ago against the AMD 64bit desktop processors and spanked them, no not in all cases or by any significant margin, but the fact a low power laptop processor (32bit) matched a 64bit mid-range/hi-end processor from AMD; that should indicate the advantages of the architecture.
If we're talking about Yonah, it was slightly slower than the X2, clock for clock (which I'd hardly consider a "spanking"). True, Yonah had no on-die memory controller, and had worse cache latency compared to its predecessor, which makes for a pretty impressive showing.
As for the future, it looks like Barcelona will have killer FP, presuming it gets released soon.
Anyway, it's obvious that the Core2's features (4-issue, macro-ops fusion, 1-cycle SSE, etc) provide the current performance leadership on the desktop, but the FSB/memory interface is weak. Which is why Intel is going the same direction AMD has gone in those areas.
Back in the 70s, analyzing Japan's rapid ascent was all the vogue. And when their economy tanked, figuring out the cause was the goal. Upon further examination, rapid-development economies are never completely "western" and free-market -- they depend heavily on government support and guidance. And that includes the United States in a previous century.
China is successful right now, but so are the other "Asian tigers" that followed Japan's model: Taiwan and South Korea.
Well, it's not like we didn't know it existed. This just props up the Standard Model some more.
Though this particle is "only" 6 GeV, it certainly is a rather rare process -- 15 candidates in five years of running. They've probably found far more top quarks. Why is it so rare? My guess is: because it contains a down quark, a bottom quark, and a strange quark, which is a unique and relatively heavy combination.
I wrote: "There are absolutely no citations in the part that talks about solid-state memory (lots of cites in the magnetic part though), so I am skeptical. If it could be done, he could have easily presented proof."
n ics)
http://en.wikipedia.org/wiki/Solid_state_(electro
Google cache:w ww.cs.auckland.ac.nz/~pgut001/pubs/secure_del.html +http://www.cs.auckland.ac.nz/~pgut001/pubs/secure _del.html&hl=en&ct=clnk&cd=1&gl=us&client=firefox- a
http://72.14.253.104/search?q=cache:PxTwoO6oZzMJ:
Note that this paper is from 1996, is from a symposium, and deals mainly with magnetic media. There are absolutely no citations in the part that talks about solid-state memory (lots of cites in the magnetic part though), so I am skeptical. If it could be done, he could have easily presented proof.
And now it's been ten years, with device area getting cut in half just about every two years. In modern DRAM, the charge storage is so minute that any accumulated oxide stress effects would be lost in the noise.
(While I'm at it, 00 -> 01 -> 10 -> 11, WTF?)
Uh, this thread is all over the place. Please disregard the previous comment.