A few things to note about nintendo portable backwards compatibility.
1: They tend to drop support for games from older generations. The game boy micro and later don't support GB/GBC games. The DSi and later don't support GBA games. 2: The DS doesn't have a link cable port so while you can play GBA games you can't use link cable (or wireless, see below) in them 3: The DSi and later don't have a GBA style cart slot, so game features that rely on that slot (for example transferring pokemon from GBA versions) can't be used on the DS. 4: There is no hardware abstraction on the wireless. This means that a GBA game can't use the wireless on the DS at all. It also means only games that were released after the DSi can use WPA, older games are stuck with wep or no security.
Several things have changed over the years with electronics.
1: everything has got much smaller, as a general rule the smaller something is the harder it is to repair and the more vulnerable it is to things like tin whiskers, 2: there are a much greater number of specialist short lifecycle parts used nowadays. 3: hardware vendors have stopped releasing schematics for their products and the complexity of the boards has reached a level where noone is going to reverse engineer said schematics. 4: in the early 2000s the EU introduced RoHS and effectively banned the use of lead in new electronics (with a handful of exceptions). Even if you don't live in Europe you were affected by this as manufacturers decided it was more economical to have one RoHS compliant product for sale worldwide than have seperate EU and non-EU versions. Lead-free solders and component finishes are far more prone to whiskers and cracking than lead based ones.
The overall result of this is that newer hardware is often much harder to keep going than older hardware.
Having said that you do want to be careful and keep an eye out for problems. Afaict the biggest cause of "damaged beyond economic repair" in 80s hardware is when a memory backup battery leaks over the main PCB and this goes unnoticed causing severe corrosion.
At the one extreme you have no telepresense at all. At the other extreme you have telepresense so good that you can operate with a high degree of autonomy in the target country. Right now we are somewhere in between, specific tasks can be done remotely but someone local has to set the equipment up for the specific task and give you access to it.
When people built centralised systems for making payments while avoiding the regular government controlled banking system the government either crushed them or forced them to become part of the system.
It was clearly within the US governments resources to crush bitcoin by gathering together enough hardware to do a 51% attack and thereby prevent unapproved transactions from entering the blockchain but they did not do so.
From those numbers, could one figure out the antenna footprint size on the surface?
You can't calculate it exactly but you can get a rough idea of the order of magnitude.
First you need to know what reference that effective radiated power is relative to. I'm not sure what the FCC convension is on this but lets assume the reference is isotropic. That would mean that the peak power density ove the sphere is 275 times the average power density.
Then we need to consider the radition pattern. In reality it won't be a simplle case of "signal here no signal there" but will gradually decay and without knowing both receiver sensitivity and antenna pattern we can't calculate things accurately. Lets make the unrealistic assumtion that for all directions the antenna either transmits fulll power or nothing. Lets also assume that the sattelite is pointing stright down.
Lets further assume that the footprint is small enough that a section of the earths surface and a section of a sphere surrounding the sattelite can be considered to have the same area. According to wolfram alpha a sphere of radius 625km has a surface area of about 4.9*10^6 square km. so 1/275 of that would be about 17.8 * 10^3 square km
In practice I would expect that this is fairly pessimistic.
Also accoridng to wolfram alpha the surface area of the earth is appoximately 510 * 10^6 square km. So if my assumptions above were correct it would take about 30K satteliates to cover the earth.
Your math is wrong. [satsig.net] It's 240ms round trip straight-on from the equator, directly below the bird, up to 280ms with both ends at extreme angles. (Damn, I thought it was 250-ish each way, not round trip.)
It depends on your definitons of "each way" and "round trip". In particular we don't tend to have servers collocated on the sattelites. so the typical satelite internet scenario is client->sattelite->base station->server->base station->sattelite->client.
So it's a minimum of 120ms client->sat 120ms sat->base 120ms base->sat 120ms sat->client
Assuming delays on the ground are negligable that is a minimum of 480ms round trip time to a server on the internet for a two way geostationary system. Add medium access control protocols that require another round trip to request permission to send a non-trvial ammount of data or significant latency on the ground and that can easilly get much worse. Afaict round trip times of over a second are quite common in practical systems.
In the easly days of sattlite internet it was common to see systems that used sattelite for downstream and dialup for upstream. This significantly reduces the total round trip time (no need for medium access control, only go via the sattelite once but runs into the problem that even assuming asymetric traffic patterns the upstream bandwidth provided by dialup is inadequate by modern standards.
That brings the bigger question of what exactly does "go metric" mean?
Does it mean that imperial measurements should be defined in terms of metric? (already done) Does it mean that government documents/signs/etc should have metric measurements? if so should they be presented equally with imperial? in preference to imperial? Should similar requirements be applied to documents used in trade? Does it mean that round metric measurements should be used in preference to round imperial ones? if so what if any measures should be taken to encourage that preference? Should steps be taken to discourage the use of imperial screw threads? if so what exactly should those steps be?
At the one extreme you have an oppresive "big government" forced metrification. At the other extreme you have what the US has now.
European and Japanese parts usually just have metric, nice and clean.
Unfortunately the continental Europeans have a habit of using "," as the decimal separator. I have no problem with them doing this when writing in their own languages but when they do it in English documents it's confusing to say the least. It also makes the diagrams pretty hard to read when you have a part whose design is clearly inch-based but all the dimensions are only given in metric.
It kinda screws some American software too. CAD packages (I'm looking at you Eagle) sometimes use imperial internally and convert to metric on the fly, but of course lose precision in places and you end up with things positioned at 11.9999998mm instead of 12mm. It doesn't matter for production but it's annoying to edit. Even if the software vendor wants to be imperial it seems like they have it backwards, because imperial units are now defined as precise metric values anyway.
It's not just american software that does it. Afaict EAGLE is german in origin. Altium Designer (which is australian in origin) has the same issue. It's annoying because when working in metric you sometimes get phantom drc errors (e.g. clearance violation, 0.1mm 0.1mm)
What I think happened is that the world of electronics used to use mostly inch-based components. Some time later metric components came along and the cad package vendors grafted on metric modes into the display code without. As a general rule it seems that 0.05 inch (1.27mm) pitch and larger components are imperial while 0.65mm (~0.0256 inch) pitch and smaller components are metric.
Another annoying one in the world of electronics is passives. An 0603 metric component is very different in size from an 0603 imperial component.
The problem comes when features start getting added to those systems that expose them to the outside world. For example someone wants to monitor and control their building remotely (or just to control it from their smartphone when they are in the building). So you start to get interconnections between the building management network and the internet and/or office wifi.
Just remember to actually use the phone from time to time or the carrier will deactivate it (i'm assuing from your use of £ that you are in the UK like me) and at least with O2 a deactivation means you lose all your credit.
From what I can gather americans get much worse terms on payg than we do.
It's a vauge statement, it could be interpreted as either unidirectional or bidirectional compatibility.
Based on what I know about the protocols I find unidirectional compatibility (thunderbolt hosts support USB devices but not vice-versa) to be the far more likely interpretation.
AIUI secondhand shops (whether specialist like gamestop or more general) work on large gross profit margins, they won't buy something unless they think they can sell it for at least half as much again what they bought it for and preferablly more. Afaict this is nessacery to make up for slow turnover, losses due to mispurchases, losses due to market changes (especially with something like recently released video games that depreciates quickly) etc but it means that people end up thinking of them as a ripoff.
That seems unlikely. Thunderbolt is a memory mapped interface with bus master DMA, USB isn't. So it's easy to put USB behind thunderbolt but very difficult to put thunderbolt (or PCIe) behind USB.
The cost of implementing all of the power management for the optional 100W facilities will be non-trivial. Substantially more than barrel jack expecting a voltage a bit higher than the laptop's battery voltage. Posh laptops may support what you suggest but I doubt it will be a universal feature.
There's a difference between a shortage of gas meaning the pumps are mostly dry, and a shortage of gas meaning the price has doubled but you can still get it anywhere.
And the difference is mostly one of policy and/or suddenness of onset rather than the total supply of gas. Supply actually running out is either a result of a very sudden supply interruption which prices can't respond to quickly enough or some entity holding prices artifically low.
With labour the situation gets even messier, people are nowhere near as fungible as gasoline is.
Afaict Intel and their customers knows there are people who want a PC but don't want a big box. They also know that some of those people will have money for a high end product and don't want to call attention to the fact that people are making a performance sacrifice by bying such a box. So they put their top end brand on a chip that is designed for such boxes just like they put their top end brand on laptop chips. For those with a bit less money to burn they market a marginally less powerful versoin of the chip under their midrange brand.
They know that the people who really need lots of CPU and/or GPU power will see through this and realise that these chips are weaker than the combination of a regular desktop CPU and a seperate graphics card but those people aren't who the marketing is aimed at.
I don't have any experience of mtp on mac os or linux but the windows MTP implementation sucks. For usb mass storage or SMB I can use any application that uses the normal windows file APIs to work with the files. The windows MTP implementation even when it's working* isn't integrated into the filesystem, so you have to manually copy stuff between the device and a real filesystem so I can work on it
In summary while I can see that the switch to MTP solves some problems on the device side it was a substantial downgrade in terms of the ability to mange the storage from a PC and the ability to access the storage from any random PC without a load of messing around first.
* And getting it to work can be a PITA sometimes, especially on XP where the driver is not included by default but some people seem to be having issues even on win7.
Modern flash in it's raw form has some nasty properties that magnetic media does not suffer from (or suffers to a much lesser extent). The erase blocks are much larger than the write blocks and much larger than the logical blocks used by most file systems. The lifetime of each erase block is determined in terms of the number of erase cycles (unlike magnetic media which doesn't really suffer from localised wearout),flash cells can also discharge over time causing a cell to validate initially but later have errors. Shrinking processes and the use of multiple voltage levels to store two (mlc) or three (tlc) bits per flash cell improves density but at the cost of making the above problems worse.
The designers of common flash media wanted their products to be a drop in replacement for magnetic storage. The result is that the flash media contains controllers that attempt to deal with the problems of the flash and present an idealised block device to the host. How successful they are in maintaining that abstraction varies massively. It's possible to engineer in nice failure modes (e.g. turning read-only on wearout) but there is no gaurantee that the manufacturer will have actually done so. Bugs in the firmware or badly handled corner cases can easily result in data corruption.
They happen because somewhere on the path a connection is overloaded and it's buffers fill up, maybe that is at your end, maybe it's at the other users end. Maybe it's somewhere in between. The internet is not and was never designed to be a network that provides bandwidth and latency gaurantees. If you want those you need to negotiate a specific route and priority access to that route between two specific locations. At that point I don't think you can reasonablly consider the conenction to be "the internet" anymore.
The article was not about adopting industrial data center voltage standards. It's about using voltages that match the batteries that you are using so you don't have to convert to anything else.
Only the smallest of solar/battery systems run at 12V.
It's quite clear to me that the author of the article is clueless.
Apart from the economical reasons as outlined by yourself, I always assumed it was a safety issue. I was taught that current kills not Voltage.
That is a common saying but highly misleading and therefore dangerous.
What kills is current through the heart and to some extent the duration of that current. Since we can't really be sure what path current will take through the body during a fault we have to consider current through the body. That current is determined by
1: the impedance of the source 2: the open circuit voltage of the source 3: the impedance of the body
A very high impedance source or a source with minimal total energy available can have a very high open circuit voltage and yet not present a hazard. This is what we see with static electricity.
However when we are talking about shocks off the mains the impedance of the source is negligable. So the important factors are the voltage of the supply and the impedance of the body. A 230V supply is more likely to deliver a fatal shock than a 120V one. This is somewhat mitigated by the fact that things like shuttered sockets and plug cavities/pin insulation are the norm in much of the EU.
The advantages of the higher voltage are efficiency and lower fire risk.
With a motorised applicance it will depend on the type of motor. Universal motors will generally be fine (maybe a bit less powerful due to the higher inductance but the design would have to be pretty marginal for that to be relavent). Motors running off DC supplies (e.g. everything you will find in your PC) will be fine too unless the PSU is very marginal. Induction and synchronous motors are more likely to fail.
lower voltages mean much higher wiring losses or much more expensive wiring (or likely a combination of both). DC at a given voltage is substantially more dangerous than AC because it is prone to arcing.
20% conversion efficiency is pretty shit by modern standards
http://www.apcmedia.com/salest... is an interesting read, it's aimed at datacenter UPS systems but many of the arguments would apply equally to a house battery system.
As for the posters mention of living in a caravan a house is much bigger than a caravan (though admittedly smaller than a datacenter). So the wiring losses are less of an issue.
My Debian stable box that gets updated at least weekly is on 3.2.
Your box is now a Debian oldstable box.
Debian stable (jessie) has 3.16, debian testing (stretch) also has 3.16 right now though i'd expect it to get 4.0 in the not too distant future. Debian unstable has 4.0.
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A few things to note about nintendo portable backwards compatibility.
1: They tend to drop support for games from older generations. The game boy micro and later don't support GB/GBC games. The DSi and later don't support GBA games.
2: The DS doesn't have a link cable port so while you can play GBA games you can't use link cable (or wireless, see below) in them
3: The DSi and later don't have a GBA style cart slot, so game features that rely on that slot (for example transferring pokemon from GBA versions) can't be used on the DS.
4: There is no hardware abstraction on the wireless. This means that a GBA game can't use the wireless on the DS at all. It also means only games that were released after the DSi can use WPA, older games are stuck with wep or no security.
Several things have changed over the years with electronics.
1: everything has got much smaller, as a general rule the smaller something is the harder it is to repair and the more vulnerable it is to things like tin whiskers,
2: there are a much greater number of specialist short lifecycle parts used nowadays.
3: hardware vendors have stopped releasing schematics for their products and the complexity of the boards has reached a level where noone is going to reverse engineer said schematics.
4: in the early 2000s the EU introduced RoHS and effectively banned the use of lead in new electronics (with a handful of exceptions). Even if you don't live in Europe you were affected by this as manufacturers decided it was more economical to have one RoHS compliant product for sale worldwide than have seperate EU and non-EU versions. Lead-free solders and component finishes are far more prone to whiskers and cracking than lead based ones.
The overall result of this is that newer hardware is often much harder to keep going than older hardware.
Having said that you do want to be careful and keep an eye out for problems. Afaict the biggest cause of "damaged beyond economic repair" in 80s hardware is when a memory backup battery leaks over the main PCB and this goes unnoticed causing severe corrosion.
The A400M is a turboprop.
It's not a black and white thing.
At the one extreme you have no telepresense at all. At the other extreme you have telepresense so good that you can operate with a high degree of autonomy in the target country. Right now we are somewhere in between, specific tasks can be done remotely but someone local has to set the equipment up for the specific task and give you access to it.
When people built centralised systems for making payments while avoiding the regular government controlled banking system the government either crushed them or forced them to become part of the system.
It was clearly within the US governments resources to crush bitcoin by gathering together enough hardware to do a 51% attack and thereby prevent unapproved transactions from entering the blockchain but they did not do so.
From those numbers, could one figure out the antenna footprint size on the surface?
You can't calculate it exactly but you can get a rough idea of the order of magnitude.
First you need to know what reference that effective radiated power is relative to. I'm not sure what the FCC convension is on this but lets assume the reference is isotropic. That would mean that the peak power density ove the sphere is 275 times the average power density.
Then we need to consider the radition pattern. In reality it won't be a simplle case of "signal here no signal there" but will gradually decay and without knowing both receiver sensitivity and antenna pattern we can't calculate things accurately. Lets make the unrealistic assumtion that for all directions the antenna either transmits fulll power or nothing. Lets also assume that the sattelite is pointing stright down.
Lets further assume that the footprint is small enough that a section of the earths surface and a section of a sphere surrounding the sattelite can be considered to have the same area. According to wolfram alpha a sphere of radius 625km has a surface area of about 4.9*10^6 square km. so 1/275 of that would be about 17.8 * 10^3 square km
In practice I would expect that this is fairly pessimistic.
Also accoridng to wolfram alpha the surface area of the earth is appoximately 510 * 10^6 square km. So if my assumptions above were correct it would take about 30K satteliates to cover the earth.
Your math is wrong. [satsig.net] It's 240ms round trip straight-on from the equator, directly below the bird, up to 280ms with both ends at extreme angles. (Damn, I thought it was 250-ish each way, not round trip.)
It depends on your definitons of "each way" and "round trip". In particular we don't tend to have servers collocated on the sattelites. so the typical satelite internet scenario is client->sattelite->base station->server->base station->sattelite->client.
So it's a minimum of
120ms client->sat
120ms sat->base
120ms base->sat
120ms sat->client
Assuming delays on the ground are negligable that is a minimum of 480ms round trip time to a server on the internet for a two way geostationary system. Add medium access control protocols that require another round trip to request permission to send a non-trvial ammount of data or significant latency on the ground and that can easilly get much worse. Afaict round trip times of over a second are quite common in practical systems.
In the easly days of sattlite internet it was common to see systems that used sattelite for downstream and dialup for upstream. This significantly reduces the total round trip time (no need for medium access control, only go via the sattelite once but runs into the problem that even assuming asymetric traffic patterns the upstream bandwidth provided by dialup is inadequate by modern standards.
That brings the bigger question of what exactly does "go metric" mean?
Does it mean that imperial measurements should be defined in terms of metric? (already done)
Does it mean that government documents/signs/etc should have metric measurements? if so should they be presented equally with imperial? in preference to imperial?
Should similar requirements be applied to documents used in trade?
Does it mean that round metric measurements should be used in preference to round imperial ones? if so what if any measures should be taken to encourage that preference?
Should steps be taken to discourage the use of imperial screw threads? if so what exactly should those steps be?
At the one extreme you have an oppresive "big government" forced metrification. At the other extreme you have what the US has now.
European and Japanese parts usually just have metric, nice and clean.
Unfortunately the continental Europeans have a habit of using "," as the decimal separator. I have no problem with them doing this when writing in their own languages but when they do it in English documents it's confusing to say the least. It also makes the diagrams pretty hard to read when you have a part whose design is clearly inch-based but all the dimensions are only given in metric.
It kinda screws some American software too. CAD packages (I'm looking at you Eagle) sometimes use imperial internally and convert to metric on the fly, but of course lose precision in places and you end up with things positioned at 11.9999998mm instead of 12mm. It doesn't matter for production but it's annoying to edit. Even if the software vendor wants to be imperial it seems like they have it backwards, because imperial units are now defined as precise metric values anyway.
It's not just american software that does it. Afaict EAGLE is german in origin. Altium Designer (which is australian in origin) has the same issue. It's annoying because when working in metric you sometimes get phantom drc errors (e.g. clearance violation, 0.1mm 0.1mm)
What I think happened is that the world of electronics used to use mostly inch-based components. Some time later metric components came along and the cad package vendors grafted on metric modes into the display code without. As a general rule it seems that 0.05 inch (1.27mm) pitch and larger components are imperial while 0.65mm (~0.0256 inch) pitch and smaller components are metric.
Another annoying one in the world of electronics is passives. An 0603 metric component is very different in size from an 0603 imperial component.
The problem comes when features start getting added to those systems that expose them to the outside world. For example someone wants to monitor and control their building remotely (or just to control it from their smartphone when they are in the building). So you start to get interconnections between the building management network and the internet and/or office wifi.
Just remember to actually use the phone from time to time or the carrier will deactivate it (i'm assuing from your use of £ that you are in the UK like me) and at least with O2 a deactivation means you lose all your credit.
From what I can gather americans get much worse terms on payg than we do.
It's a vauge statement, it could be interpreted as either unidirectional or bidirectional compatibility.
Based on what I know about the protocols I find unidirectional compatibility (thunderbolt hosts support USB devices but not vice-versa) to be the far more likely interpretation.
AIUI secondhand shops (whether specialist like gamestop or more general) work on large gross profit margins, they won't buy something unless they think they can sell it for at least half as much again what they bought it for and preferablly more. Afaict this is nessacery to make up for slow turnover, losses due to mispurchases, losses due to market changes (especially with something like recently released video games that depreciates quickly) etc but it means that people end up thinking of them as a ripoff.
That seems unlikely. Thunderbolt is a memory mapped interface with bus master DMA, USB isn't. So it's easy to put USB behind thunderbolt but very difficult to put thunderbolt (or PCIe) behind USB.
The cost of implementing all of the power management for the optional 100W facilities will be non-trivial. Substantially more than barrel jack expecting a voltage a bit higher than the laptop's battery voltage. Posh laptops may support what you suggest but I doubt it will be a universal feature.
There's a difference between a shortage of gas meaning the pumps are mostly dry, and a shortage of gas meaning the price has doubled but you can still get it anywhere.
And the difference is mostly one of policy and/or suddenness of onset rather than the total supply of gas. Supply actually running out is either a result of a very sudden supply interruption which prices can't respond to quickly enough or some entity holding prices artifically low.
With labour the situation gets even messier, people are nowhere near as fungible as gasoline is.
Afaict Intel and their customers knows there are people who want a PC but don't want a big box. They also know that some of those people will have money for a high end product and don't want to call attention to the fact that people are making a performance sacrifice by bying such a box. So they put their top end brand on a chip that is designed for such boxes just like they put their top end brand on laptop chips. For those with a bit less money to burn they market a marginally less powerful versoin of the chip under their midrange brand.
They know that the people who really need lots of CPU and/or GPU power will see through this and realise that these chips are weaker than the combination of a regular desktop CPU and a seperate graphics card but those people aren't who the marketing is aimed at.
I don't have any experience of mtp on mac os or linux but the windows MTP implementation sucks. For usb mass storage or SMB I can use any application that uses the normal windows file APIs to work with the files. The windows MTP implementation even when it's working* isn't integrated into the filesystem, so you have to manually copy stuff between the device and a real filesystem so I can work on it
In summary while I can see that the switch to MTP solves some problems on the device side it was a substantial downgrade in terms of the ability to mange the storage from a PC and the ability to access the storage from any random PC without a load of messing around first.
* And getting it to work can be a PITA sometimes, especially on XP where the driver is not included by default but some people seem to be having issues even on win7.
You have fallen for marketing bullshit.
Modern flash in it's raw form has some nasty properties that magnetic media does not suffer from (or suffers to a much lesser extent). The erase blocks are much larger than the write blocks and much larger than the logical blocks used by most file systems. The lifetime of each erase block is determined in terms of the number of erase cycles (unlike magnetic media which doesn't really suffer from localised wearout),flash cells can also discharge over time causing a cell to validate initially but later have errors. Shrinking processes and the use of multiple voltage levels to store two (mlc) or three (tlc) bits per flash cell improves density but at the cost of making the above problems worse.
The designers of common flash media wanted their products to be a drop in replacement for magnetic storage. The result is that the flash media contains controllers that attempt to deal with the problems of the flash and present an idealised block device to the host. How successful they are in maintaining that abstraction varies massively. It's possible to engineer in nice failure modes (e.g. turning read-only on wearout) but there is no gaurantee that the manufacturer will have actually done so. Bugs in the firmware or badly handled corner cases can easily result in data corruption.
They happen because somewhere on the path a connection is overloaded and it's buffers fill up, maybe that is at your end, maybe it's at the other users end. Maybe it's somewhere in between. The internet is not and was never designed to be a network that provides bandwidth and latency gaurantees. If you want those you need to negotiate a specific route and priority access to that route between two specific locations. At that point I don't think you can reasonablly consider the conenction to be "the internet" anymore.
The article was not about adopting industrial data center voltage standards. It's about using voltages that match the batteries that you are using so you don't have to convert to anything else.
Only the smallest of solar/battery systems run at 12V.
It's quite clear to me that the author of the article is clueless.
Apart from the economical reasons as outlined by yourself, I always assumed it was a safety issue. I was taught that current kills not Voltage.
That is a common saying but highly misleading and therefore dangerous.
What kills is current through the heart and to some extent the duration of that current. Since we can't really be sure what path current will take through the body during a fault we have to consider current through the body. That current is determined by
1: the impedance of the source
2: the open circuit voltage of the source
3: the impedance of the body
A very high impedance source or a source with minimal total energy available can have a very high open circuit voltage and yet not present a hazard. This is what we see with static electricity.
However when we are talking about shocks off the mains the impedance of the source is negligable. So the important factors are the voltage of the supply and the impedance of the body. A 230V supply is more likely to deliver a fatal shock than a 120V one. This is somewhat mitigated by the fact that things like shuttered sockets and plug cavities/pin insulation are the norm in much of the EU.
The advantages of the higher voltage are efficiency and lower fire risk.
I would think a kettle would be fine.
With a motorised applicance it will depend on the type of motor. Universal motors will generally be fine (maybe a bit less powerful due to the higher inductance but the design would have to be pretty marginal for that to be relavent). Motors running off DC supplies (e.g. everything you will find in your PC) will be fine too unless the PSU is very marginal. Induction and synchronous motors are more likely to fail.
lower voltages mean much higher wiring losses or much more expensive wiring (or likely a combination of both). DC at a given voltage is substantially more dangerous than AC because it is prone to arcing.
20% conversion efficiency is pretty shit by modern standards
http://www.apcmedia.com/salest... is an interesting read, it's aimed at datacenter UPS systems but many of the arguments would apply equally to a house battery system.
As for the posters mention of living in a caravan a house is much bigger than a caravan (though admittedly smaller than a datacenter). So the wiring losses are less of an issue.
My Debian stable box that gets updated at least weekly is on 3.2.
Your box is now a Debian oldstable box.
Debian stable (jessie) has 3.16, debian testing (stretch) also has 3.16 right now though i'd expect it to get 4.0 in the not too distant future. Debian unstable has 4.0.