Let’s imagine a laptop with one single USB socket (as worst case scenario)

Would it work if I wanted to attach, simultaneously:
USB keyboard
USB mouse
USB DVD drive

is a 3-scoket hub all that’s needed – when do you need a powered hub ?

On the tiny chance that it didn’t have an ethernet socket, would a USB-ethernet cable also work

You’ll need a powered hub for the DVD drive

really hammy?

The drive itself is has a power supply; do I still have to power the hub?

thanks

You didn’t put that in the OP Scaredy – in that case no.

The drive itself is has a power supply; do I still have to power the hub?

Then probably not, but… it would be wise to get one anyway – you don’t need to have it powered on all the time, but the facility would be there in the future when you need, for example, to connect a 2.5″ external drive./something else which needs power.

OK, I’ll look at powered hubs, ta

But in principle the multiple USB “feeds” can all go through one port on the PC ?

Yes. Each USB device has its own address. That’s the whole purpose of a hub. The only restriction is power*, as one USB port is only allowed to supply a certain number of amps, which is why you need a powered hub if you have devices that need that exceed that limit.

*(well there is some loss of throughput too but that’s only an issue if you start putting multiple high speed devices on the one hub).

The only restriction is power

That’s not strictly true, though it is true for pretty much all practical purposes. A USB host supports 128 devices (including itself).

You need sufficient power to drive whatever devices you attach, and an individual (USB2) port can supply 500mA. Power requirements will be device-specific, so if demand is greater than supply you’ll need to add an external power source. For a keyboard, mouse and something that’s already powered, I wouldn’t worry about it.

The new Dell docking station plugs into the usb3,does ethernet, screen and USB. I’d still rather have then separate though