USB?

That is an Apple extension cable that used to ship with USB keyboards. Here is mine, alongside the cable end of a keyboard (model A1048) whose USB plug works with the extension cable:

Note that Apple notched the plug on the keyboard cable to accommodate the "key" in the extension cable. The notch does not prevent the board from being used without the extension. I also received this kind of extender with two A1243 "Aluminum" boards I bought.

I see two part numbers associated with this basic design in eBay adverts: 591-0181 and 591-0240:

Apple USB Extension Cable | eBay

Hi romad,

We still have one of those extension cables in service. When we bought Dear Wife a new iMac in 2012 she did not like the wireless keyboard with which it shipped (no numeric keypad), much preferring the older A1048 that was on the 2005 eMac that her iMac replaced. The workspace required a longer KB cable so the board and its extension that came with the eMac are still serving on a newer Mac.

That female end does not look quite right for a USB female. I am looking at a cable like that on my desk right now and on yours I see, for example, a little white triangle of plastic in the bottom of the female end that is probably what is stopping anything from being plugged in there. No such on mine which I use routinely for flash drives. It is possible that is a cable provided with some specific device for using with a standard USB socket on a computer.

Ah, so it was an Apple-proprietary USB extension cable. I couldn't find a USB standard that described the female socket with the middle spike which is why I figured it was proprietary design and not a standard USB design.

Perhaps it was an eMac-only design to keep the keyboards/mice from being stolen. My iMac Bondi Blue Rev. B came with standard USB-A connections, as have all my successive Macs.

Edit. I just checked my iMac G5 ALS keyboard and it to is an A1048 but it has the standard USB-A connector. This seems to confirm the notched connector was used only on the eMac.

Then it must be model-dependent. Can you find an EMC number on the bottom of yours? The one pictured is EMC 1944. We have three of these cables, the one that came with the eMac 2005, and two that were in the boxes of two Apple aluminum wired boards I bought as as separate components directly from Apple.

The A1048 I pictured has the keyway but did not come with an extension cable. One of the local computer stores bought a bunch of unused A1048s in bulk (shrink-wrapped without a box) and sold then on for a bargain price. So I have no idea what model they were intended for.

Oops! I had just looked at the USB ports on the back of the keyboard. I unplugged the cable and looked at the male connector and it DOES have a notch! And it also has 1944 for the EMC number.

Now we are back at why the notch! Do you still have the eMac? If so are the USB ports standard female A ports?

If so are the USB ports standard female A ports?

Yep, std ports on the eMac. The notch on the connector does not interfere with with plugging the connector into regular ports. The system seems to be rigged to prevent the extension cable from being used as anything but a keyboard accessory without limiting how the keyboard can be used.

No Apple logos on mine, and all three came from directly from Apple.

Looks like a proprietary USB cable. What is the hardware it is used with?

Richard, I can see the USB symbol on the female connector; is there an Apple logo on either of the connectors? If so, then we'll know it is an Apple cable.

Actually, I was replying/asking Allen - I should have made that clear. But please see my question to you regarding any logos/symbols on the cable, Richard.