For my 2 examples
Why would for example is thunderbolt faster than usb 2? Aren’t they both just copper with a rubber case?
Why is hdmi faster and carry more info that vga if they are both basically strands of copper?
Are these performance differences more related to the tech in the devices and not the cables? If so aren’t they made with the same materials as devices from decades ago?
In: 1
There’s a few factors:
The precision of the signal, the capacity of the device bus controller, where the bus connects to the bridge, and where your device needs to get to on the main bus.
So first is the actual signal being transferred. For simplicity, imagine Morse code with a flashlight in the middle of a busy highway. As cars flick past, their lights will briefly shine on the receiver just like the flashlight, and you won’t be able to differentiate which is which. The solution, is to make the flashlight blink at a controlled speed and interval. Now you can disregard all the “noise” and extra light except at the exact moment you need to know what the flashlight is trying to tell you. Even with this though, you’ll still have issues because there night be lights in your face at the exact wrong moment. The solution, is to slow down the flashlight so that even if the headlights are in your face for a second, the flashlight was going slow enough you don’t miss any information.
Now back to computers. Computers have the same issue called Elecreo Magnrtic Interference where the signal in a wire can get distorted by the “noise” of the environment. The more noise there is, the slower you have to go so you can distinguish the real signal from the noise. If you insulate your cables from one another and your environment, you reduce interference and this can go faster.
Next is the device bus controller. The USB or HDMI plug you plug in isn’t just a hunk of metal. It has a microchip in it to do all that nifty stuff with making sure the signal is timed appropriately, and detecting when interference has damaged the signal. Sometimes it’s even able to repair a damaged signal. This microchip only goes so fast, and uses components that sample data only so quickly. A tiny computer is used to interpret the signal on the wire and it is a bottleneck. Cheap cables usually mean cheap chips, usually mean cheap components usually means slow or innaccurate components. So, to compensate, the whole data transfer process is slowed down.
Then there’s the main bus of your computer, and a computer science concept called the bridge. The bus is the common set of wires everyone uses to talk to everyone else inside the computer. CPU wants to access ram, same wires as when the GPU reads something directly off the hardrive. We break up devices on the bus into two parts, called the north and south bridge. Quick devices making frequent bus accesses live on the south bridge. They get premium access, preference, and better hardware because if they slow down everything slows down. The north bridge is for slower less dense traffic, like your keyboard mouse USB stick and hard drive. Depending on the capabilities of your device or of the computer it’s plugged into, you may get different optimizations of bus access. Sometimes interrupts (signals that let your CPU know that a device needs attention) can be buffered on the north bridge then sent, and processed by the CPU all at once to save time with bus switching. This means that the device has better priority and runs faster without slowing everything else down. Some devices can perform DMA where the CPU isn’t involved at all and two devices can speak directly without serving interrupts.
It ultimately comes down to a balance between design, cost, and purpose.
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