Currently, DOCSIS cable modems use a TDMA scheme for return traffic. (Basically, divide the wavelengths up into "time slots" and each modem gets a certain time slot. The signal is generally modulated using 16-QAM. Think of two waves offset by 90 degrees, one vertical and one horizontal. Add to that 2 levels of amplitude for each wave. So, you can have 16 combinations. Or 4 bits for each wavelength of signal. You can increase the numbers of levels of different amplitude to increase your possible bit combinations per wavelength, but this is risky and few cable companies actually do it.
With this system running in the typical 25-35Khz frequency, you can have enough time slots for 400-600 modems, and about 7Mb of shared traffic.
To me, it's amazing they can build silicon to distinguish 500 different cable modems within microseconds. Kind of like what really happens in a Pentium IV.
But, this stuff is susceptible to noise and it can become hard to tell what bits are meant to be on the line if there's enough noise.
It's a good model, but I have no idea how you do it over the air, unless you increase the signal so high that the noise floor drowns out. But then jets would fall from the sky and we'd all get throbbing headaches.. or something.
goofballs who wiped out mailboxes without having a proper backup in place
I have some empathy for these goofballs. I'd say that that many accounts was probabbly about 60GB of data. 60GB out of God knows how many terabytes.
It would be impossible to centralize that much data, except for perhaps the database to verify users. Mbox data would have to be distributed. That would eliminate any single point of failure, but also increase the chance of a small failure. Say you have 60 servers, and 6,000 disks. Say you try to replicate all this, so the same backup software runs on each of the 60 servers. You have people adding/removing and changing passwords constantly. Not to mention, you have a few gigabytes of data rolling over on this system every second. Say for whatever reason, a small percentage of accounts on one of those file systems was not being backed up. Perhaps there was some database corruption, in the database which points to the users mbox. Sometimes these things get tied together, and the loss of the accounts correlated to them not being backed up. The complexity and variability of such a large distributed system is easy to underestimate.
Users are absolutely entitled to expect that their provider doesn't delete their mail with no backups available.
I'm not exactly sure what you mean by "entitled to expect."
Gmail is a free (to the user) service. The user might expect it to be reliable, but they are entitled to nothing. If it all goes away, there's no recourse. Also, in light of all the free competing e-mail services these days, most ISP's offer e-mail as a courtesy and will not guarantee it's integrity. It's probabbly carefully worded in every AUP. To practice a business where you are legally responsible for terabytes of customer data is scary can of worms... let Citibank deal with that.
I work in the ISP business and can tell you that the overhead for e-mail is greater then any other service provided. Every other piece of vital data here is peanuts compared to the size of our customer e-mail storage arrays. We back it up as often as we can. It's an absolutely enormous amount of data that changes every second. We do the best we can but, Hell no, I don't want to be liable for it. I would hope you don't expect me to. Even though I know it's being rsyncd off site twice a day I still advise customers every chance I get. Download your messages and archive the important ones periodically.
As the old saying goes, the only person you can rely on is yourself.
Oh no you didn't!?? Oh... yes, yes you DID.. and you got modded insightful?
Modders, you do realize that this is the inverse of the same argument that is championed out in defense of Windows' traditional insecurity, no? The whole, it's the most popular OS and therefore the biggest target thing. Usually if you play that card, you get 37 rebuttal's and a -1 overrated.
If Bioware can sell $30 software with unique CD-Keys printed on the inside of each jewel case, why can't Linksys sell $40 routers with unique admin passwords printed on each manual. Or better yet, make the default password the last 6 digits of the LAN side MAC address, that can't be terribly hard to manufacture.
Seriously, you could even honestly market them as "more secure."
This says one thing. I want a desktop that works and lets me get my work done and I don't care if it costs.
I'm not the first to bring this point, surely, but I'll say it anyway.
In 1985, the home computing world was Commodore's oyster. I mean really, it can't be understated. Jack Trameil's "Computer's for the Masses, not the Classes" outsold all others by two or three times. Many forget they were the biggest baddest computer company out there. Unfortunately, they did a pitiful amount of R&D in the latter years and had HORRIBLE management.
If Apple, who has some business sense, can merge Jack's paradigm into their own, that would be exciting. Maybe they can do the inverse of the Toyota / Lexus thing; start a new company.
But I don't think they will. I don't see OSX penetrating todays $299 PC market, unfortunately. And it's not really even price point, it's the perception of Apple being expensive. They need to change that perception.
I can't drive anywhere short of 300 miles and buy a cheap Mac in a store.
Or, maybe it's just hard to estimate the lifespan of one of a kind state of the art technology in an environment that is 120000000 miles away and unlike most everything on Earth.
Ever use VNC over a sub 5Mb connection? With even 100ms+ latency? Connected to a high resolution desktop?
I frequently connect to a 1024x768x16bit Windows 2000 server and it's slow and ugly even across my uber fast gigabit office network. Sure, it's serviceable for an admin, but try playing Quake. You get the double dose of VNC input latency and connection latency. Google video even looks like crap.
Until we get near light speed broadband, I don't see this replacing a desktop.
I love mine. I bought the cheaper ($350) 4Gb surf model. Initially, there were some concerns that the Surf had non-upgradeable soldered on memory.
Fortunately not, and I was able to upgrade the memory to 1Gb. I don't think I'll have any storage problems, as SD cards are now rediculasly cheap.
I had a 2gb one laying around, and used that.
I tweaked the standard xandros install to provide a full KDE desktop. I built a custom kernel with USB support built in and large memory support so I could replicate the Linux install and boot it off a flash drive and use > 2gb of memory.
I'm considering developing some games for the thing. It would certainly be a cool platform. The external display works great, and if you hook up a USB keyboard and mouse, you have a tiny quiet energy efficient desktop.
Everywhere I take the thing people ask questions. It's very cool.
It's a shame people don't realize what space technology really means to humanity.
- Satellites: Thanks for DirectTV Sputnik.
- Meteorology: Thanks for the nightly satellite picture every evening news.
- Agraculture: How much more food does the world produce because of surveys of our fields from space?
- Science Fiction: It's enriched the lives of so many, but how much did real space exploration inspire it's creation?
- Politics: The space race offered both a rallying call for nations to come together and enrich their economy, and a catalyst for many cooperative endeavors between nations which were otherwise unfriendly.
- Peace and the Military: I'd argue that the SR-71 and all of our reconnaissance satellite photography did more to prevent war and paranoia then any other US/Russian military technology. Although it gave us ICBMs..
- Science Education: Nothing makes you consider the errors of dogmatic religion like breathtaking Hubble deep field imagery.
- Consumer Technology: Computers, materials science and aerospace engineering owe so many of their innovations to the challenges offered by space.
And, you know, it is in our interest to find a way to live off of this rock. We can't struggle with keeping the Earth in balance with humanity forever, we won't win.
A user compromise on a Linux system would provide suitable functionality for today's typical malware.
On my defualt, fully security patched Mandriva workstation:
- I have full read write execute permission to my home directory. - I can run wget to download anything, and put it as an executable anywhere in my home directory. - I can use perl, awk, whois, grep, sed, whatever, to craft some pretty nasty scripts. - I can use telnet and I could write an expect script to send spam with telnet. - Or, I could just download a precrafted elf binary to run as a mini-mail server in my home directory. - It's not to hard to imagine that I could pop something in/tmp or elsewhere that would persist on the system even after the user had been deleted. - I could fire off a fork bomb that will crash the system instantly.
I does not take to much imagination to figure out some suitably bad stuff that you could do as any old user.
Of course, hiding yourself on the system and ensuring your survival could be difficult. It would be easy to find all the nasty services running as said user, since top, ps, etc.. would not have been compromised.
I don't know if it's worth anything but STALKER was the only game I played to completion this year.
I'm just so sick of Fantasy. I'm sick of elves, magic and special potions. I'm sick of WW2. Bioshock, while good, was not real to me, it just seemed over the top; to far fetched, sensational and psedu-scientific. A little make believe is ok, but spouting fire and lightning bolts from your hands because of a genetic enhancement potion stopped being intriguing to me. It just seems ridicules as I approach 30.
Playing something that really challenged me, based on a real area, with very realistic weapons and a gritty post-apocalyptic atmosphere was refreshing. I also enjoyed the depth and detail. The translations for all that is said in Russian reveal some very interesting dialog. The almost endless buildings to hunt around in and the 7 different endings to try gave the game more replayability than most. The amount of different equipment to use led to lots of debate and online discussion of strategy.
It was buggy, but in terms of breaking new ground, I think it gets overlooked when compared to the more sensational BioShock.
I bought a LaserJet 4p on Ebay for something like $30 plus $20 shipping. It lasted almost 2 years before I had to get toner. Again, Ebay, $12. I print perhaps 75 pages a month.
So total expense for 3+ years of B&W laser printing, $62. I figure I saved 3 or 4 hundred over a comparable, slightly lower quality, slower inkjet.
How is this modded insightful? Just because it poo-poos America? The Energiya is not in production. We don't know if the larger (theoretical) models are worth anything. They may be based on prior proven technology but so is the Ares. There are certain to be major engineering differences (fuel, electronics, avionitcs) that we don't have the support infrastructure for. And lastly, even though NASA has a pretty good history of cooperating with foreign agencies in space, what is wrong with building something ourselves, giving Americans jobs and bolstering our economy (and those of foreign contractors) in the name of space exploration?
I understand it's not all black and white, and that there is a big fat contract waiting for Lockheed Martin, but I can't see contracting a big rocket from the Russians as anything but more trouble. At least if we fail, we are the only ones to blame.
If a big Energiya was ready to go, reliable and we had the support systems to deal with it, you'd have a point.
Humans evolved into the dominate primate. The ones that stood upright, got more sensory input from a higher perspective and ate more protein to use in developing raw brain material succeeded. We evolved the capacity to create modern medicine. Those that had the desire and the smarts to save people with technology found their way to the top of the gene pool.
So, when you say "Mother Nature" does things for a reason, you are right. That reason, though, might not be the one obvious to you.
Exactly. Best book I ever read. Summed up, it feels good to think your privy to secret knowledge, to expose alleged conspiracy and to dream of the fantastic. But just because something feels nice does not make it so.
So much of this can be combated with a foundation in the scientific method and skeptical inquiry. They try to make that the corner stone of 6th grade science education, but it's forgotten by the time you get to the 11th grade. I'd like to see it reinforced all the way through college.
It's still good however, that someone is pointing out some of the non-sense on youtube.
Slashdot Mirror
Currently, DOCSIS cable modems use a TDMA scheme for return traffic. (Basically, divide the wavelengths up into "time slots" and each modem gets a certain time slot. The signal is generally modulated using 16-QAM. Think of two waves offset by 90 degrees, one vertical and one horizontal. Add to that 2 levels of amplitude for each wave. So, you can have 16 combinations. Or 4 bits for each wavelength of signal. You can increase the numbers of levels of different amplitude to increase your possible bit combinations per wavelength, but this is risky and few cable companies actually do it.
With this system running in the typical 25-35Khz frequency, you can have enough time slots for 400-600 modems, and about 7Mb of shared traffic.
To me, it's amazing they can build silicon to distinguish 500 different cable modems within microseconds. Kind of like what really happens in a Pentium IV.
But, this stuff is susceptible to noise and it can become hard to tell what bits are meant to be on the line if there's enough noise.
It's a good model, but I have no idea how you do it over the air, unless you increase the signal so high that the noise floor drowns out. But then jets would fall from the sky and we'd all get throbbing headaches.. or something.
I was joking, but I got all intellectual about it. :-p
It's p2p diversion... It was the RIAA. Brittney Spears or Brittney next door? Curiosity and perversion are certainly more powerful than greed.
It would be impossible to centralize that much data, except for perhaps the database to verify users. Mbox data would have to be distributed. That would eliminate any single point of failure, but also increase the chance of a small failure. Say you have 60 servers, and 6,000 disks. Say you try to replicate all this, so the same backup software runs on each of the 60 servers. You have people adding/removing and changing passwords constantly. Not to mention, you have a few gigabytes of data rolling over on this system every second. Say for whatever reason, a small percentage of accounts on one of those file systems was not being backed up. Perhaps there was some database corruption, in the database which points to the users mbox. Sometimes these things get tied together, and the loss of the accounts correlated to them not being backed up. The complexity and variability of such a large distributed system is easy to underestimate.
It happens to the best of us, really.
I hear ya. That rsync churns all bloody night.
I'm not exactly sure what you mean by "entitled to expect."
Gmail is a free (to the user) service. The user might expect it to be reliable, but they are entitled to nothing. If it all goes away, there's no recourse. Also, in light of all the free competing e-mail services these days, most ISP's offer e-mail as a courtesy and will not guarantee it's integrity. It's probabbly carefully worded in every AUP. To practice a business where you are legally responsible for terabytes of customer data is scary can of worms... let Citibank deal with that.
I work in the ISP business and can tell you that the overhead for e-mail is greater then any other service provided. Every other piece of vital data here is peanuts compared to the size of our customer e-mail storage arrays. We back it up as often as we can. It's an absolutely enormous amount of data that changes every second. We do the best we can but, Hell no, I don't want to be liable for it. I would hope you don't expect me to. Even though I know it's being rsyncd off site twice a day I still advise customers every chance I get. Download your messages and archive the important ones periodically.
As the old saying goes, the only person you can rely on is yourself.
Yes, but you have to compile it.
Oh no you didn't!??
Oh... yes, yes you DID.. and you got modded insightful?
Modders, you do realize that this is the inverse of the same argument that is championed out in defense of Windows' traditional insecurity, no? The whole, it's the most popular OS and therefore the biggest target thing. Usually if you play that card, you get 37 rebuttal's and a -1 overrated.
If Bioware can sell $30 software with unique CD-Keys printed on the inside of each jewel case, why can't Linksys sell $40 routers with unique admin passwords printed on each manual. Or better yet, make the default password the last 6 digits of the LAN side MAC address, that can't be terribly hard to manufacture.
Seriously, you could even honestly market them as "more secure."
I bet you're fun to work with. One of those, always has a suggestion for management types.
..and they'll never have a reason to learn anything about it if we keep making all the decisions without them.
Or, maybe they should just ask us experts at slashdot for our opinions.
I'm not the first to bring this point, surely, but I'll say it anyway.
In 1985, the home computing world was Commodore's oyster. I mean really, it can't be understated. Jack Trameil's "Computer's for the Masses, not the Classes" outsold all others by two or three times. Many forget they were the biggest baddest computer company out there. Unfortunately, they did a pitiful amount of R&D in the latter years and had HORRIBLE management.
If Apple, who has some business sense, can merge Jack's paradigm into their own, that would be exciting. Maybe they can do the inverse of the Toyota / Lexus thing; start a new company.
But I don't think they will. I don't see OSX penetrating todays $299 PC market, unfortunately. And it's not really even price point, it's the perception of Apple being expensive. They need to change that perception.
I can't drive anywhere short of 300 miles and buy a cheap Mac in a store.
Or, maybe it's just hard to estimate the lifespan of one of a kind state of the art technology in an environment that is 120000000 miles away
and unlike most everything on Earth.
Ever use VNC over a sub 5Mb connection? With even 100ms+ latency? Connected to a high resolution desktop?
I frequently connect to a 1024x768x16bit Windows 2000 server and it's slow and ugly even across my uber fast gigabit office network. Sure, it's serviceable for an admin, but try playing Quake. You get the double dose of VNC input latency and connection latency. Google video even looks like crap.
Until we get near light speed broadband, I don't see this replacing a desktop.
But you idea is definitely cool for work!
I love mine. I bought the cheaper ($350) 4Gb surf model. Initially, there were some concerns that the Surf had non-upgradeable soldered on memory. Fortunately not, and I was able to upgrade the memory to 1Gb. I don't think I'll have any storage problems, as SD cards are now rediculasly cheap. I had a 2gb one laying around, and used that.
I tweaked the standard xandros install to provide a full KDE desktop. I built a custom kernel with USB support built in and large memory support so I could replicate the Linux install and boot it off a flash drive and use > 2gb of memory.
I'm considering developing some games for the thing. It would certainly be a cool platform. The external display works great, and if you hook up a USB keyboard and mouse, you have a tiny quiet energy efficient desktop.
Everywhere I take the thing people ask questions. It's very cool.
This is the same useless periodical that continually gives Nortron Internet Security a 4 or 5 star rating year after year. Enough said.
....or Steve Wozniak. *ducks
It's a shame people don't realize what space technology really means to humanity.
- Satellites: Thanks for DirectTV Sputnik.
- Meteorology: Thanks for the nightly satellite picture every evening news.
- Agraculture: How much more food does the world produce because of surveys of our fields from space?
- Science Fiction: It's enriched the lives of so many, but how much did real space exploration inspire it's creation?
- Politics: The space race offered both a rallying call for nations to come together and enrich their economy, and a catalyst for many cooperative endeavors between nations which were otherwise unfriendly.
- Peace and the Military: I'd argue that the SR-71 and all of our reconnaissance satellite photography did more to prevent war and paranoia then any other US/Russian military technology. Although it gave us ICBMs..
- Science Education: Nothing makes you consider the errors of dogmatic religion like breathtaking Hubble deep field imagery.
- Consumer Technology: Computers, materials science and aerospace engineering owe so many of their innovations to the challenges offered by space.
And, you know, it is in our interest to find a way to live off of this rock. We can't struggle with keeping the Earth in balance with humanity forever, we won't win.
A user compromise on a Linux system would provide suitable functionality for today's typical malware.
/tmp or elsewhere that would persist on the system even after the user had been deleted.
On my defualt, fully security patched Mandriva workstation:
- I have full read write execute permission to my home directory.
- I can run wget to download anything, and put it as an executable anywhere in my home directory.
- I can use perl, awk, whois, grep, sed, whatever, to craft some pretty nasty scripts.
- I can use telnet and I could write an expect script to send spam with telnet.
- Or, I could just download a precrafted elf binary to run as a mini-mail server in my home directory.
- It's not to hard to imagine that I could pop something in
- I could fire off a fork bomb that will crash the system instantly.
I does not take to much imagination to figure out some suitably bad stuff that you could do as any old user.
Of course, hiding yourself on the system and ensuring your survival could be difficult. It would be easy to find all the nasty services running as said user, since top, ps, etc.. would not have been compromised.
I don't know if it's worth anything but STALKER was the only game I played to completion this year.
I'm just so sick of Fantasy. I'm sick of elves, magic and special potions. I'm sick of WW2. Bioshock, while good, was not real to me, it just seemed over the top; to far fetched, sensational and psedu-scientific. A little make believe is ok, but spouting fire and lightning bolts from your hands because of a genetic enhancement potion stopped being intriguing to me. It just seems ridicules as I approach 30.
Playing something that really challenged me, based on a real area, with very realistic weapons and a gritty post-apocalyptic atmosphere was refreshing. I also enjoyed the depth and detail. The translations for all that is said in Russian reveal some very interesting dialog. The almost endless buildings to hunt around in and the 7 different endings to try gave the game more replayability than most. The amount of different equipment to use led to lots of debate and online discussion of strategy.
It was buggy, but in terms of breaking new ground, I think it gets overlooked when compared to the more sensational BioShock.
Whoa, big Deja Vu. For a second I thought it was 10AM EST again.
Yes, this is very good advice, especially if you do just black and white printing.
Color ones are even pretty reasonable.
I bought a LaserJet 4p on Ebay for something like $30 plus $20 shipping.
It lasted almost 2 years before I had to get toner. Again, Ebay, $12.
I print perhaps 75 pages a month.
So total expense for 3+ years of B&W laser printing, $62. I figure I saved
3 or 4 hundred over a comparable, slightly lower quality, slower inkjet.
How is this modded insightful? Just because it poo-poos America? The Energiya is not in production. We don't know if the larger (theoretical) models are worth anything. They may be based on prior proven technology but so is the Ares. There are certain to be major engineering differences (fuel, electronics, avionitcs) that we don't have the support infrastructure for. And lastly, even though NASA has a pretty good history of cooperating with foreign agencies in space, what is wrong with building something ourselves, giving Americans jobs and bolstering our economy (and those of foreign contractors) in the name of space exploration?
I understand it's not all black and white, and that there is a big fat contract waiting for Lockheed Martin, but I can't see contracting a big rocket from the Russians as anything but more trouble. At least if we fail, we are the only ones to blame.
If a big Energiya was ready to go, reliable and we had the support systems to deal with it, you'd have a point.
It's a bit of a paradox isn't it?
Humans evolved into the dominate primate. The ones that stood upright, got more sensory input from a higher perspective and ate more protein to use in developing raw brain material succeeded. We evolved the capacity to create modern medicine. Those that had the desire and the smarts to save people with technology found their way to the top of the gene pool.
So, when you say "Mother Nature" does things for a reason, you are right. That reason, though, might not be the one obvious to you.
Exactly.
Best book I ever read. Summed up, it feels good to think your privy to secret knowledge, to expose alleged conspiracy and to dream of the fantastic.
But just because something feels nice does not make it so.
So much of this can be combated with a foundation in the scientific method and skeptical inquiry. They try to make that the corner stone of 6th grade science education, but it's forgotten by the time you get to the 11th grade. I'd like to see it reinforced all the way through college.
It's still good however, that someone is pointing out some of the non-sense on youtube.