There is no reason that a traditional PC BIOS can't boot a 3TB drive. The bios just reads the first sector of the drive and runs the code, it doesn't need to care what type of partition table is used. So the 2TB limit of the DOS style partition table is irrelevent to the first stage of booting a PC. AIUI grub2 has no problems being booted by a traditional PC bios and then going on to read a GPT partition table and load linux from it.
The inability to boot windows on a 3TB GPT drive with a traditional PC bios is entirely microsoft's fault.
Higher wiring costs (both materials and labour). Higher end system costs. More restricted choice of end systems. Most likely higher resistive losses in wiring. Greater difficulty installing and removing stuff*. Higher losses in the primary side of the isolating switched mode converter in your end system.
For 230/400V TP+N AC you have.
Losses from inverters in UPS systems and rectifiers in end devices. Vendor lockin when paralell running UPS units.
* A new connector as proposed in the GP post could help to some extent with this but the characteristics of DC, the higher currents involved and the fact it would be a niche product mean that even if such a connector were standardised it would be a lot bulkier and more expensive than the connectors used for hooking up servers to AC supplies.
Another important thing to remember is that the display driver model was overhauled between XP and Vista. So afaict while they are packaged up in the same installer the XP driver and the Vista+ driver are really two different drivers. While i'm sure there will be some shared code I suspect that a heck of a lot of the code is specific to either the "XPDM" driver or the "WDDM" driver.
48 volts is high enough that is doesn't need the big fat wires that 12VDC high-amperage connections do
48V while not as bad as 12V still means much thicker cables and/or higher cable losses (most likely some combination of both) than normal mains voltages.
Servers at full load can draw a heck of a lot of power. 500W is not unreasonable for a beefy 1U server, put 42 of those in a rack and you are looking at 21KW.
Feed those servers with a 240V single phase supply and you are looking at about 88A. That is high but managable with the sort of cable sizes you can find at most electrical wholesalers. Feed those servers with a 240V/415V three phase plus neutral system about 29A in each phase conductor (and ideally nothing in the neutral). Easy to deal with Feed them of a telco style -48V DC system and you are looking at about 438A. That is getting into the territory of busbars.
and computers would just need a DC-DC converter to convert the incoming voltage to the 12 and 5 volt rail voltages.
To prevent large currents flowing where they are not wanted you'd almost certainly want isolating DC to DC converters in the computers. An isolating DC-DC converter isn't much different from an AC-DC power supply (the main difference is that the rectifier and power factor correction stuff can be eliminated).
UDP provides a mechanism (source ports) for multiple client applications on the same host to coexist. Furthermore through the mangling of source ports NATs can allow multiple hosts running UDP applications to coexist and communicate with the same servers from behind one public IP.
If you created a new IP protocol then you'd have to implement your own mechanism for multiple client applications on the same host to exist. Furthermore your system would likely break if two users behind the same NAT tried to access the same server with it because unless the NAT specifically supported your new protocol* it would have no way to differentiate between the traffic to different clients.
The overhead of building on top of UDP is pretty minimal, a source and destination port which as i've mentioned above are useful for allowing applications to coexist and a checksum which may or may not be redundant with checksums in your new protocol.
* Which will likely happen sometime arround when hell freezes over.
Google's reason for doing this is to lower their costs associated with better security. This creates a 3 way instead of a 5 way exchange for the security protocol setup. Fewer connections less load on their stuff and less stuff they have to buy.
IMO It's not just direct financial costs.
Google is now into mobile in a pretty big way. A "GSM based" smartphone would typically move between.
GRPS: encryption exists but it's an old design and has security flaws that can't really be fixed due to compaitbility with legacy equipment. Fortunately the equipment needed to exploit things is expensive enough to keep most people out. 3G: better encryption systems but they can be subverted by forcing the phone to drop back to GRPS. Public wifi networks: Either no encryption or encryption with a fairly well known shared key. Trivially easy for an attacker to set themselves up as a man in the middle. Owners: home wifi, usually wpa encrypted nowadays but older installs may be either unencrypted or encyrpted with a broken encryption system and some people may use an insecure key to make it easier to remember.
As well as security problems some of these networks are likely to be high latency (i've seen latencies in the seconds on GRPS). So every round trip added reduces the quality of the user experiance. Getting the number of round trip times to set up a secure connection reduces the user experiance impact of increasing security which makes it an easier sell to do it.
I don't know where you are getting your numbers from but europasat in the UK lists offers for sattelite internet on a pay as you go basis for £7 per gigabyte and you can get a lower cost per gigabyte by committing to a certain number of gigabytes per month. That seems to be in the same ballpark as cellular services.
Maratime and mobile sattelite internet services are far more expensive but afaict they are still not anywhere near the prices you give.
I kinda like allen keys too, they are simple and seem fairly robust. I just wish there weren't so damn many sizes some of which are very similar but not quite similar enough to fit each other properly due to both metric and imperial sizes being in use.
I don't understand. I'm not a parser, but to my eye that means "assign." If you wanted to compare, you would do "if ($foo == 1 + $bar)", no?
That is what it means to php and other languages that borrow heavilly from c. The fact that it means that to your eyes is probablly a result of you having programmed in c based languages for many years. Other languages do other things, Pascal uses = for comparison and:= for assignment, Basic uses = for both and decides which to do based whether you are writing a statement or a parameter. So it's an easy mistake to make and a difficult one to spot. Especially for people who move between languages that borrow from C and languages that don't.
It wouldn't be so bad if it was actually an error to try and do an assignment in a conditional and to try (and for that matter to do a comparision in a statement on it's own) but in C based languages assignments evalulate to the value of what is being assigned and C and php both have very loose typing*. The result is that when you forget the second equals sign you get a program that doesn't give any errors but doesn't do what you expect either.
As another poster has pointed out modern C compilers have now put a warning in place for this common mistake but interpreted languages like php don't really have the luxury of doing that.
* Java is an example of a language that borrows sytax from C but whose strong typing makes this much less of an issue it's pretty unusual to be comparing booleans for equality and trying to do an assignment of any other type in a conditional will result in type errors.
It's not so much generating html, you can do that just as easilly in many other languages.
The hook with php and similar tools (asp, jsp) is that you can put a little bit of php *inside* a html (or other text based format) document whereas with a more conventional programming language you'd have to either write code to read the html from a file and make substitutions or convert your html into a massive series of print statements. That massively lowers the barrier for people who want to add a little bit of interactivity to their website or move the menus into a common file rather than repeating them in every page.
It's marginally useful even in more complex web applications because it lets you make the "view" essentially a html document and yet pass it paramters with the data it is supposed to include but it probablly doesn't make up for php's other defficiencies there..
One can divide by whether the cartridges are memory mapped and can be read one address at a time or are on a controller that looks and acts more like a disc controller transferring data in large blocks.
I know on the nintendo side the GBA was the last system to use traditional memory mapped cartridges and even there they no longer ran at full CPU speed so high performance code had to be copied into ram first. DS cartrdiges are more "disk like". I don't know any technical details about the vita but i'd be very surprised if it's cartridges weren't also "disk like".
There is Mysql documentation that claims that the GPL applies not only to their server software and their client access libraries but to their wire protocol such that even if you clean room reimplemented the client access libraries (which I belive someone eventually did) those reimplemented client access libraries would still be bound by the GPL.
I don't know if they ever tried to enforce that though.
Are the pilots making errors in situations that the autopilot would have handled fine or are they making errors because they are in a dificult situation that the autopilot was unable to handle forcing them to take over?
No, they don't. Microsoft shut down Live Messenger in April. You're expected to use Skype instead.
So the news articles claimed but at least for me pidgin still seems to connect sucessfully to it and get the buddy list (though it's a while since i've actually tried to talk to anyone on it, been using irc more laterly)
Service piggybacked on home wifi without externally mounted access points is going to suck unless you are very close to the house from which is served. Wifi is a pretty short range system as it is and the external walls of the house. I doubt there will be any decent handoff support either and I think it is likely we will see several competing systems.
So to use it you will have to find a house with a good signal and then stay there while you use it. Like with the old "rabbit phones" but unlike the old rabbit phones they won't be signposted and it will be difficult to receive incoming communications.
You connect and then you have to login. No login means no route to the internet.
If someone else is already using the "public" side of the access point when you want to connect then you could probably hijack their session by cloning their IP and mac address but if only the "private" side is in use that option is ruled out.
It wasn't an electronic copy of the domesday book, it was a project collecting various stuff including photos and videos from schools that was supposedly in the spirit of the domesday book and putting it into a newflangled computer based system.
The problem with that project was it was ahead of it's time and as such needed some pretty esoteric hardware*. Normal computing hardware from that era is still easy enough to find but the esoteric stuff needed for the domesday syste is not.
* Specifically it used a BBC master (common) with a 6502 second processor card (fairly rare), a SCSI card (very rare) and a specific model of laserdisk player (very rare)
1: Mozilla didn't like the use of the firefox name with the "unbranded" logos and debian considered the copyright license of the "branded" logos non-free. 2: Mozilla wanted to be asked for aproval for every patch.
Personally I say kudos to debian for not rolling over to these demands.
Why would we need yet another standard. Simply don't trust open access points and encrypt everything, use HTTPS, IMAPS, SMTPS, SFTP,... VPN if necessary.
The procedure for safely using an untrusted wireless access point that has a captive portal with a VPN goes something like:
1: shut down any internet using applications that could potentially send private information over unencrypted connections. Hope you didn't miss any. 2: connect to the wifi 3: launch your browser with special parameters to make sure it doesn't try to do a session restore or otherwise leak any private data from pre-existing cookies. Alternatively keep a seperate browser that you only use for interacting with captive portals. 4: deal with the captive portal, hope they used ssl to encrypt any authentication details. 5: make sure your VPN is configured to send all traffic through the VPN and not for "split horizon" operation 6: launch your internet using apps
This is awkward as heck on a regular desktop/laptop OS, i'm not sure it's feasible at all on most phone/tablet operating systems. I very much doubt any significant number of users are going to do it.
Specifically the release file is signed. That contains the secure hashes of the package lists files which in turn contain secure hashes of the actual packages. If files don't match the expected hashes apt will refuse to use them. If the release file is unsigned or signed by an unknown key apt will warn the user and ask them if they want to continue.
The proper way to resolve this exact problem is to require sources to have a valid digital signature signed by a trusted party
We DO have signed repositories and apt DOES check the signatures. However there are a couple of traps the unwary could fall into.
1: Some people may have just decided to ignore the security warning rather than properly set up the key for a third party repository. 2: The first assumption of someone getting a key error who isn't aware that the domain is no longer in trusted hands may well be to think that they haven't installed the key properly and to go to reinstall the key. Unfortunately they are unlikely to do so in a secure manner. They are likely to either go to the website on the domain in question to get the key or download it from a public keyserver by it's 32-bit key ID (which are easy enough to collide).
Slashdot Mirror
There is no reason that a traditional PC BIOS can't boot a 3TB drive. The bios just reads the first sector of the drive and runs the code, it doesn't need to care what type of partition table is used. So the 2TB limit of the DOS style partition table is irrelevent to the first stage of booting a PC. AIUI grub2 has no problems being booted by a traditional PC bios and then going on to read a GPT partition table and load linux from it.
The inability to boot windows on a 3TB GPT drive with a traditional PC bios is entirely microsoft's fault.
Comparing 48V DC to 240/415V TP+N AC.
For 48V DC you have
Higher wiring costs (both materials and labour).
Higher end system costs.
More restricted choice of end systems.
Most likely higher resistive losses in wiring.
Greater difficulty installing and removing stuff*.
Higher losses in the primary side of the isolating switched mode converter in your end system.
For 230/400V TP+N AC you have.
Losses from inverters in UPS systems and rectifiers in end devices.
Vendor lockin when paralell running UPS units.
* A new connector as proposed in the GP post could help to some extent with this but the characteristics of DC, the higher currents involved and the fact it would be a niche product mean that even if such a connector were standardised it would be a lot bulkier and more expensive than the connectors used for hooking up servers to AC supplies.
Another important thing to remember is that the display driver model was overhauled between XP and Vista. So afaict while they are packaged up in the same installer the XP driver and the Vista+ driver are really two different drivers. While i'm sure there will be some shared code I suspect that a heck of a lot of the code is specific to either the "XPDM" driver or the "WDDM" driver.
That may be true for home users but in many office and education situations it's common to see locked down accounts on XP
48 volts is high enough that is doesn't need the big fat wires that 12VDC high-amperage connections do
48V while not as bad as 12V still means much thicker cables and/or higher cable losses (most likely some combination of both) than normal mains voltages.
Servers at full load can draw a heck of a lot of power. 500W is not unreasonable for a beefy 1U server, put 42 of those in a rack and you are looking at 21KW.
Feed those servers with a 240V single phase supply and you are looking at about 88A. That is high but managable with the sort of cable sizes you can find at most electrical wholesalers.
Feed those servers with a 240V/415V three phase plus neutral system about 29A in each phase conductor (and ideally nothing in the neutral). Easy to deal with
Feed them of a telco style -48V DC system and you are looking at about 438A. That is getting into the territory of busbars.
and computers would just need a DC-DC converter to convert the incoming voltage to the 12 and 5 volt rail voltages.
To prevent large currents flowing where they are not wanted you'd almost certainly want isolating DC to DC converters in the computers. An isolating DC-DC converter isn't much different from an AC-DC power supply (the main difference is that the rectifier and power factor correction stuff can be eliminated).
UDP provides a mechanism (source ports) for multiple client applications on the same host to coexist. Furthermore through the mangling of source ports NATs can allow multiple hosts running UDP applications to coexist and communicate with the same servers from behind one public IP.
If you created a new IP protocol then you'd have to implement your own mechanism for multiple client applications on the same host to exist. Furthermore your system would likely break if two users behind the same NAT tried to access the same server with it because unless the NAT specifically supported your new protocol* it would have no way to differentiate between the traffic to different clients.
The overhead of building on top of UDP is pretty minimal, a source and destination port which as i've mentioned above are useful for allowing applications to coexist and a checksum which may or may not be redundant with checksums in your new protocol.
* Which will likely happen sometime arround when hell freezes over.
Google's reason for doing this is to lower their costs associated with better security. This creates a 3 way instead of a 5 way exchange for the security protocol setup. Fewer connections less load on their stuff and less stuff they have to buy.
IMO It's not just direct financial costs.
Google is now into mobile in a pretty big way. A "GSM based" smartphone would typically move between.
GRPS: encryption exists but it's an old design and has security flaws that can't really be fixed due to compaitbility with legacy equipment. Fortunately the equipment needed to exploit things is expensive enough to keep most people out.
3G: better encryption systems but they can be subverted by forcing the phone to drop back to GRPS.
Public wifi networks: Either no encryption or encryption with a fairly well known shared key. Trivially easy for an attacker to set themselves up as a man in the middle.
Owners: home wifi, usually wpa encrypted nowadays but older installs may be either unencrypted or encyrpted with a broken encryption system and some people may use an insecure key to make it easier to remember.
As well as security problems some of these networks are likely to be high latency (i've seen latencies in the seconds on GRPS). So every round trip added reduces the quality of the user experiance. Getting the number of round trip times to set up a secure connection reduces the user experiance impact of increasing security which makes it an easier sell to do it.
I don't know where you are getting your numbers from but europasat in the UK lists offers for sattelite internet on a pay as you go basis for £7 per gigabyte and you can get a lower cost per gigabyte by committing to a certain number of gigabytes per month. That seems to be in the same ballpark as cellular services.
Maratime and mobile sattelite internet services are far more expensive but afaict they are still not anywhere near the prices you give.
I kinda like allen keys too, they are simple and seem fairly robust. I just wish there weren't so damn many sizes some of which are very similar but not quite similar enough to fit each other properly due to both metric and imperial sizes being in use.
I don't understand. I'm not a parser, but to my eye that means "assign." If you wanted to compare, you would do "if ($foo == 1 + $bar)", no?
That is what it means to php and other languages that borrow heavilly from c. The fact that it means that to your eyes is probablly a result of you having programmed in c based languages for many years. Other languages do other things, Pascal uses = for comparison and := for assignment, Basic uses = for both and decides which to do based whether you are writing a statement or a parameter. So it's an easy mistake to make and a difficult one to spot. Especially for people who move between languages that borrow from C and languages that don't.
It wouldn't be so bad if it was actually an error to try and do an assignment in a conditional and to try (and for that matter to do a comparision in a statement on it's own) but in C based languages assignments evalulate to the value of what is being assigned and C and php both have very loose typing*. The result is that when you forget the second equals sign you get a program that doesn't give any errors but doesn't do what you expect either.
As another poster has pointed out modern C compilers have now put a warning in place for this common mistake but interpreted languages like php don't really have the luxury of doing that.
* Java is an example of a language that borrows sytax from C but whose strong typing makes this much less of an issue it's pretty unusual to be comparing booleans for equality and trying to do an assignment of any other type in a conditional will result in type errors.
It's not so much generating html, you can do that just as easilly in many other languages.
The hook with php and similar tools (asp, jsp) is that you can put a little bit of php *inside* a html (or other text based format) document whereas with a more conventional programming language you'd have to either write code to read the html from a file and make substitutions or convert your html into a massive series of print statements. That massively lowers the barrier for people who want to add a little bit of interactivity to their website or move the menus into a common file rather than repeating them in every page.
It's marginally useful even in more complex web applications because it lets you make the "view" essentially a html document and yet pass it paramters with the data it is supposed to include but it probablly doesn't make up for php's other defficiencies there..
One can divide by whether the cartridges are memory mapped and can be read one address at a time or are on a controller that looks and acts more like a disc controller transferring data in large blocks.
I know on the nintendo side the GBA was the last system to use traditional memory mapped cartridges and even there they no longer ran at full CPU speed so high performance code had to be copied into ram first. DS cartrdiges are more "disk like". I don't know any technical details about the vita but i'd be very surprised if it's cartridges weren't also "disk like".
Afaict the "cylindrical viewer" is silverlight based, the "panoramic viewer" is flash based.
There is Mysql documentation that claims that the GPL applies not only to their server software and their client access libraries but to their wire protocol such that even if you clean room reimplemented the client access libraries (which I belive someone eventually did) those reimplemented client access libraries would still be bound by the GPL.
I don't know if they ever tried to enforce that though.
Note that BT spun off their mobile phone operation in late 2001.
Are the pilots making errors in situations that the autopilot would have handled fine or are they making errors because they are in a dificult situation that the autopilot was unable to handle forcing them to take over?
No, they don't. Microsoft shut down Live Messenger in April. You're expected to use Skype instead.
So the news articles claimed but at least for me pidgin still seems to connect sucessfully to it and get the buddy list (though it's a while since i've actually tried to talk to anyone on it, been using irc more laterly)
Edit: apparently the old rabbit phones couldn't take incoming calls either.
Service piggybacked on home wifi without externally mounted access points is going to suck unless you are very close to the house from which is served. Wifi is a pretty short range system as it is and the external walls of the house. I doubt there will be any decent handoff support either and I think it is likely we will see several competing systems.
So to use it you will have to find a house with a good signal and then stay there while you use it. Like with the old "rabbit phones" but unlike the old rabbit phones they won't be signposted and it will be difficult to receive incoming communications.
You connect and then you have to login. No login means no route to the internet.
If someone else is already using the "public" side of the access point when you want to connect then you could probably hijack their session by cloning their IP and mac address but if only the "private" side is in use that option is ruled out.
It wasn't an electronic copy of the domesday book, it was a project collecting various stuff including photos and videos from schools that was supposedly in the spirit of the domesday book and putting it into a newflangled computer based system.
The problem with that project was it was ahead of it's time and as such needed some pretty esoteric hardware*. Normal computing hardware from that era is still easy enough to find but the esoteric stuff needed for the domesday syste is not.
* Specifically it used a BBC master (common) with a 6502 second processor card (fairly rare), a SCSI card (very rare) and a specific model of laserdisk player (very rare)
Afaict there were two issues.
1: Mozilla didn't like the use of the firefox name with the "unbranded" logos and debian considered the copyright license of the "branded" logos non-free.
2: Mozilla wanted to be asked for aproval for every patch.
Personally I say kudos to debian for not rolling over to these demands.
Why would we need yet another standard. Simply don't trust open access points and encrypt everything, use HTTPS, IMAPS, SMTPS, SFTP, ... VPN if necessary.
The procedure for safely using an untrusted wireless access point that has a captive portal with a VPN goes something like:
1: shut down any internet using applications that could potentially send private information over unencrypted connections. Hope you didn't miss any.
2: connect to the wifi
3: launch your browser with special parameters to make sure it doesn't try to do a session restore or otherwise leak any private data from pre-existing cookies. Alternatively keep a seperate browser that you only use for interacting with captive portals.
4: deal with the captive portal, hope they used ssl to encrypt any authentication details.
5: make sure your VPN is configured to send all traffic through the VPN and not for "split horizon" operation
6: launch your internet using apps
This is awkward as heck on a regular desktop/laptop OS, i'm not sure it's feasible at all on most phone/tablet operating systems. I very much doubt any significant number of users are going to do it.
Specifically the release file is signed. That contains the secure hashes of the package lists files which in turn contain secure hashes of the actual packages. If files don't match the expected hashes apt will refuse to use them. If the release file is unsigned or signed by an unknown key apt will warn the user and ask them if they want to continue.
The proper way to resolve this exact problem is to require sources to have a valid digital signature signed by a trusted party
We DO have signed repositories and apt DOES check the signatures. However there are a couple of traps the unwary could fall into.
1: Some people may have just decided to ignore the security warning rather than properly set up the key for a third party repository.
2: The first assumption of someone getting a key error who isn't aware that the domain is no longer in trusted hands may well be to think that they haven't installed the key properly and to go to reinstall the key. Unfortunately they are unlikely to do so in a secure manner. They are likely to either go to the website on the domain in question to get the key or download it from a public keyserver by it's 32-bit key ID (which are easy enough to collide).