[chaosmachine]

Apple USB keyboards notoriously come with a USB extension cable that's notched in the middle, so it doesn't fit other USB devices.

Here's a picture: http://imgur.com/Aweqo.jpg

Technically, if you're willing to risk damaging it, you can force a regular USB device in there, but it sticks out at a weird angle because of the notch.

[philwelch]

That's an example of lock-in that makes absolutely no sense. Why would you do that with USB extension cords of all things? The only reason I can think of--it physically locks the cables together better so it doesn't pop open in the middle of the extension cord where it's difficult to reach and reattach.

[gxti]

I'm pretty sure they do it because the keyboard can't source the required 500mA of current. They "proprietarize" it in order to keep people from plugging high-current devices in.

[chaosmachine]

The keyboard itself contains a 2 port USB hub (regular ports, btw, with enough juice to power a Wacom tablet and charge my phone at the same time), so I'm not sure that makes sense.

[gxti]

Never mind, then. I have no idea why they did it but there's probably a perfectly valid technical explanation.

[gmlk]

I don't know about the current systems, have been wireless for more then 4 years now, but the original iMac had non-standard USB usage because Apple wanted the "power" button in the keyboard, while the USB protocol did not support this usage, at least it didn't at the time; I don't know if this has changed since then.

http://forums.macrumors.com/showpost.php?p=11022485&post...