Nibbed USB extension cable fits only Apple Keyboard

On Fri, 29 Sep 2006, Alan Forkosh wrote:

> On Sep 28, 2006, at 11:42 AM, Geoffrey Odhner wrote:
>
>> ... While I was there I also read your article on the USB
>> extension cord that comes
>> with their keyboard. It *is* strange. I can't think of a reason why
>> they would do it, but perhaps there is one. ...
>
> The nibbed USB cable connectors are not new. The extension cable
> associated with my vintage 2001 G4 Quicksilver also has the nib which
> mates with the grove in the connector for a companion Apple keyboard.

The USB specification contains no provision for such a device and
therefore by definition no such thing can exist. A cable might correctly
be described as a USB-compatible extension lead.

The keyboard extension leads which came with some G3s and G4s are treated
in the same way as leads for e.g. digital cameras with non-standard
connectors, that is they are considered as 'captive' and an integral part
of the device they connect to. The non-standard connector is used because
without it the cable would be non-standards-compliant, but with it the
whole assembly is tested for compliance with USB specs as one unit.

--
Alistair Riddell - BOFH
Microsoft - because god hates us

> The nibbed USB cable connectors are not new. The extension cable
> associated with my vintage 2001 G4 Quicksilver also has the nib
> which mates with the grove in the connector for a companion Apple
> keyboard.

I used to work on the electronic design of a USB device, and I seem
to remember that extension cables are problematic in light of USB
certification. A USB device might conform to the standards (and
operate reliably) with its built-in cable. But adding an arbitrarily
long extension cable to it could cause the device to fail. It could
be that Apple is trying to force you to use the extension cable only
with the device (the keyboard) that has been tested with it and known
to conform to the standards.

Note that I still think this is a silly reason to make a proprietary
USB extension cable, but I offer it up as a possible explanation. I
think people should not be treated like such babies -- let me decide
if I want to risk non-compliance. :-)

_________________
=> Jolin Warren, Edinburgh, Scotland

On Oct 1, 2006, at 2:11 AM, Jolin M Warren wrote:

> I used to work on the electronic design of a USB device, and I seem
> to remember that extension cables are problematic in light of USB
> certification. A USB device might conform to the standards (and
> operate reliably) with its built-in cable. But adding an arbitrarily
> long extension cable to it could cause the device to fail. It could
> be that Apple is trying to force you to use the extension cable only
> with the device (the keyboard) that has been tested with it and known
> to conform to the standards.
>
> Note that I still think this is a silly reason to make a proprietary
> USB extension cable, but I offer it up as a possible explanation. I
> think people should not be treated like such babies -- let me decide
> if I want to risk non-compliance. :-)

I've got USB extension cables - they work with every device I've ever
used. I've never tried on a USB2 device (HD or iPod), but with
keyboards, scanners, hubs, etc.


Kirk
           Author of: The Mac OS X Command Line: Unix Under the Hood
                      http://www.mcelhearn.com/unix.html
                - - - - - -
              Read my blog: Kirkville -- http://www.mcelhearn.com
           Musings, Opinion and Miscellanea, on Macs, iPods and more

On 30 Sep 2006, at 18:11 , Jolin M Warren wrote:
> Note that I still think this is a silly reason to make a proprietary
> USB extension cable, but I offer it up as a possible explanation. I
> think people should not be treated like such babies -- let me decide
> if I want to risk non-compliance. :-)

Well, the fact is, if you wear down the nib and use the extension
cable on another USB device, it doesn't work.


--
The person on the other side was a young woman. Very obviously a
young woman. There was no possible way that she could have been
mistaken for a young man in any language, especially Braille.

The "special" USB extension cable works just fine on other USB devices. You simply insert the USB device into the nibed USB extension cable at a slight angle and then push.

At 14:49 on 03-10-2006, Kirk McElhearn wrote:
> I've got USB extension cables - they work with every device I've
> ever used. I've never tried on a USB2 device (HD or iPod), but with
> keyboards, scanners, hubs, etc.

I've got USB 'extension leads' too (including one that's 2-3m!). I'm
not saying they don't exist or don't work. It's simply that they are
not compliant with the official USB spec. As Alistair Riddel said
(30-09-2006 email):

> The USB specification contains no provision for such a device and
> therefore by definition no such thing can exist. A cable might
> correctly be described as a USB-compatible extension lead.

So Apple's 'USB extension cable' is not actually a separate item when
viewed from the perspective of USB certification. It is part of the
keyboard. I'm suggesting that this is the reason for its nib -- not
because USB 'extension leads' (including Apple's) won't work with
other devices. They probably will (but then again they might not --
there's no guarantee).

Cheers,
Jolin

_________________
=> Jolin Warren, Edinburgh, Scotland

At 2:49 PM -0700 2006/10/03, Kirk McElhearn wrote:

>I've got USB extension cables - they work with every device I've ever
>used. I've never tried on a USB2 device (HD or iPod), but with
>keyboards, scanners, hubs, etc.

        Elgato ships a short (1'?) USB extension cable with the EyeTV
hybrid, which is definitely a USB 2.0 device (it pumps out video over
USB), and mine works well with a 3' or so extension cable that came
with something else (flash reader?).


                                                Chris
--
Chris Pepper: <http://www.reppep.com/~pepper/>
                             <http://www.reppep.com/weblog/pepper/>
Rockefeller University: <http://www.rockefeller.edu/>