If you’ve used a USB device over the last twenty years, the following may seem familiar to you:
When it was introduced, the USB port was a major improvement over other means of connecting devices to computers, such as serial and parallel ports. It was smaller, faster and offered support for a much broader array of peripherals.
It did share one aspect with serial and parallel ports, though: it was not reversible. That is, you could only insert a USB cable one way. The right way. Which way was the right way? Looking again at the animation above you might logically think that the right way is the one where the USB symbol is facing up. And you’d be correct–sometimes. Because there was no standard for how ports were oriented. The front-facing ports on my PC, in fact, require the label-side to be facing down. You can tell which way is the right way by examining the port closely but you need to be quite close and most ports are on the back of the computer or are otherwise not easy to eyeball. You could throw out your back trying to figure out how to insert a $10 flash drive.
But even if you know which way is the right way there is something subtly terrible about the way USB plugs works that makes it feel like it’s not going in correctly even when it is. This leads to the triple attempt:
- Insert correct way, feel resistance, remove USB cable
- Insert wrong way, feel resistance, remove USB cable
- Insert correct way again, feel resistance, determine that this is either the actual correct way or you’ve gone mad, decide it is correct and wiggle/push until the USB cable is finally and firmly plugged in
- Have a stiff drink at the thought of having to go through this every time you connect a USB device
The newest USB standard, USB-C, is fully reversible. There is the correct way and the other correct way to insert a USB-C cable. I suppose you could try to insert a USB-C cable sideways and that would be incorrect but you would in fact need to be mad or have had too many stiff drinks to think this might work.
Why did the USB spec go through multiple revisions over the course of 20+ years before some clever person said, “Let’s make it reversible”? I do not know. But at least this bad design is now a better one.
See also: every other non-reversible cable in the history of the world.