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.

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.

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.

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'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.