Could someone explain why we can’t just plug the average PC etc into a ‘raw’ internet line (like just entering a house) and have a mini modem on the motherboard do the translation work?
I know there’s a limit to IP addresses, and that it’s maybe easier to have a little box do the work where it enters a building.
… but apart from that?
The PC’s modem uses the ethernet protocol, which is basically standard for computer networks. All PCs have onboard ethernet capability.
The internet itself, the network of networks, uses a bunch of different technologies/protocols to connect those networks together.
As an analogy, imagine a car, with its rubber wheels. Those rubber wheels are basically designed for pavement. There are some exceptions of course but basically our basic road design is pavement with rubber tires running on it. Every car’s got the rubber tire interface.
But then you don’t just have road networks, you’ve got the things that connect road networks together. In some places it’s an airplane, in others it’s a boat, or a bridge, or a train, or a spaceship.
Because of various challenges of connecting distant road networks together by connecting legs, we use various different technologies for it.
It’s a two-tier system. You’ve got networks, and then you’ve got the internet. Computers are designed to navigate the networks, via their onboard ethernet cards. The internet is designed to make the multiple networks operate like one network, by tunneling through the twisted vagaries of the real world. Because the internet is the part of that which crosses the real world, it’s the part of that which is the most varied in its forms.
The box at the wall is the interface between the predictable world of your home ethernet network, and the more varied world of long-range signal conduction.