Odd USB Extension Cable
isw
was an Apple-branded USB extension (male "A" on one end, female "A" on
the other) with the addition that the female connector has a little bump
sticking into the side of the socket so that no "ordinary" male USB plug
can be inserted. I'm told that this cable is for use with an Apple
keyboard (which presumably has a little notch to match the bump).
Now, the result of this is that the keyboard's plug can be inserted into
*any* USB socket, while nothing *but* the keyboard can use the extension
cable.
What's up with that? What is so special about that extension cable that
it must not be used for anything except that one keyboard?
Isaac
Doug Anderson
I don't know the answer to your question.
I do know that I've taken such cables and forced ordinary male
connectors into that notched female connectors, and except for the
fact that this was very hard to do, it has worked fine.
(I think the only devices I've done this with are keyboards though.)
Ben
I think it was to ensure that you were using a high quality cable as the
keyboard has a hub built in for the mouse etc, however it does seem a
touch pointless as you could replace it with any USB extension cable
(however USB extension cables were quite scarce in the early days).
Ben.
nospam
<i...@witzend.com> wrote:
apple used to provide keyboard extension cables that could only be used
for extending the keyboard. it was incredibly stupid.
salgud
Not stupid from Apple's point of view. If you could only use it for the
keyboard, you'd have to buy another to hook up something else. More sales,
more profits.
Mike Rosenberg
> > apple used to provide keyboard extension cables that could only be used
> > for extending the keyboard. it was incredibly stupid.
>
> Not stupid from Apple's point of view. If you could only use it for the
> keyboard, you'd have to buy another to hook up something else. More sales,
> more profits.
That would be true if Apple sold such USB extension cables.
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nospam
<spamb...@comcast.net> wrote:
> > apple used to provide keyboard extension cables that could only be used
> > for extending the keyboard. it was incredibly stupid.
>
> Not stupid from Apple's point of view.
it's very stupid, and fortunately they realized it.
> If you could only use it for the
> keyboard, you'd have to buy another to hook up something else. More sales,
> more profits.
more sales for someone *else*, you mean. apple doesn't sell generic usb
cables.
of course, they could have made the keyboard cable a little longer in
the first place but that would offend steve's sense of aesthetics.
Erik Richard Sørensen
Nearly no other USB extension cables have this 'lock', which can mean
that the plugs can easily be taken from each others and you siddenly sit
with a 'non-working' keyboard. - I have had this 'problem' with one of
my friends. - Suddenly he calls me to tell that he can't do anything
with his mouse or keyboard... He has one of the extension cables without
the 'lock', so I told him to just looke if the plugs were connected
beneith his writing table... I think you can guess the rest..-)
This extension cable was/is dedicated to and delievered along with the
black/silver and white Apple Pro keyboards, which all have the short
'tale', where some of the dedicated iMac keyboards could be either with
a short or long 'tale' - as well as the 'hockey-puck' mouse...
Cheers, Erik Richard
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David Empson
For some reason, Apple thought it was a good idea to supply some of
their keyboards with relatively short bonded USB cables, but included an
extension cable with models where it was likely that the computer would
be installed some distance from the desktop (PowerMacs and similar).
The USB standard does not allow the use of extension cables with
arbitrary devices. The female "A" connector is never supposed to be used
on a cable. Any such cable you happen to be able to buy cannot be
certified as compliant with USB.
Apple's keyboard extender cable has a notch to prevent it being used
with other USB devices. Its use in conjunction with the keyboard is a
known pairing which Apple can test and establish that the combination
complies with USB electrical and signalling standards.
--
David Empson
dem...@actrix.gen.nz
nospam
Empson <dem...@actrix.gen.nz> wrote:
> The USB standard does not allow the use of extension cables with
> arbitrary devices. The female "A" connector is never supposed to be used
> on a cable. Any such cable you happen to be able to buy cannot be
> certified as compliant with USB.
flash card readers often come with a usb extension cable that doesn't
have that idiotic locking crap.
> Apple's keyboard extender cable has a notch to prevent it being used
> with other USB devices. Its use in conjunction with the keyboard is a
> known pairing which Apple can test and establish that the combination
> complies with USB electrical and signalling standards.
that's a nice spin, but it doesn't explain why other companies manage
to do it without the lock silliness.
isw
dem...@actrix.gen.nz (David Empson) wrote:
There were a lot of "answers" to my question. This is the only one that
makes sense. Basically, Apple did not want to be in the position of
providing a "USB" cable which was not compliant with the USB standard.
Thanks
Isaac
David Empson
> In article <1jby5p5.1yvwe2a1isorokN%dem...@actrix.gen.nz>, David
> Empson <dem...@actrix.gen.nz> wrote:
>
> > The USB standard does not allow the use of extension cables with
> > arbitrary devices. The female "A" connector is never supposed to be used
> > on a cable. Any such cable you happen to be able to buy cannot be
> > certified as compliant with USB.
>
> flash card readers often come with a usb extension cable that doesn't
> have that idiotic locking crap.
A few USB devices with bonded plugs that have unusually wide profile
include a short USB A plug to A socket extension cable. I've seen this
with some USB flash drives and many of the Elgato devices (e.g.
Turbo.264 and EyeTV Hybrid).
I haven't looked this up in detail, but it is possible that the
combination of a short A-A cable and bonded A plug is allowed in recent
USB standards. I note that none of the devices I've seen with this
arrangement have the "Certified USB" logo on them.
Even if the device is not certified, the use of a short extension cable
with a device that has a bonded plug is not likely to cause timing or
electrical problems.
> > Apple's keyboard extender cable has a notch to prevent it being used
> > with other USB devices. Its use in conjunction with the keyboard is a
> > known pairing which Apple can test and establish that the combination
> > complies with USB electrical and signalling standards.
>
> that's a nice spin, but it doesn't explain why other companies manage
> to do it without the lock silliness.
Probably because they are playing fast and loose with USB and not
getting their devices certified.
Joining two cables together is not permitted in the USB standard, so the
only way Apple could have got away with it and be certified is by
proving it worked in that combination. They couldn't supply a general
purpose USB extension cable so they came up with a modified plug that
mostly prevented the extension cable being used with other devices.
On the other hand, I can't see any logo on my Apple Pro Keyboard or
extender cable suggesting it is certified, so perhaps Apple just wanted
to discourage outright abuse of USB standards.
--
David Empson
dem...@actrix.gen.nz
nospam
<dem...@actrix.gen.nz> wrote:
> > flash card readers often come with a usb extension cable that doesn't
> > have that idiotic locking crap.
>
> A few USB devices with bonded plugs that have unusually wide profile
> include a short USB A plug to A socket extension cable. I've seen this
> with some USB flash drives and many of the Elgato devices (e.g.
> Turbo.264 and EyeTV Hybrid).
it's not that short. it's probably 2-3 feet long (haven't measured it).
David Empson
You might have one like that, but it is a violation of the USB standard.
My flash card reader has the correctly implemented USB Mini-B socket on
the reader, with a USB A to Mini-B cable.
--
David Empson
dem...@actrix.gen.nz
isw
nospam <nos...@nospam.invalid> wrote:
If it doesn't reach from where you keyboard is to where your Mac is,
it's too short. I have a MacBook and an "aluminum" Apple keyboard in a
two-monitor setup, with the Mac to the left of the external monitor and
the keyboard in front of it. Because the USB connector on the Mac is on
the left side, the keyboard cable without an extension won't work,
unless I route the cable straight across the keyboard of the Mac.
Isaac
Malcolm
The notch also ensures that only one extension can be used with the
keyboard. You can't daisy-chain them. This means Apple doesn't have
to make the keyboard work with an arbitrary length of USB.
emelvy
> On 2010-01-06 13:50:38 -0500, isw <i...@witzend.com> said:
>
> > Someone just "gifted" me with a large box of assorted cables. Among them
> > was an Apple-branded USB extension (male "A" on one end, female "A" on
> > the other) with the addition that the female connector has a little bump
> > sticking into the side of the socket so that no "ordinary" male USB plug
> > can be inserted. I'm told that this cable is for use with an Apple
> > keyboard (which presumably has a little notch to match the bump).
>
> The notch also ensures that only one extension can be used with the
> keyboard. You can't daisy-chain them. This means Apple doesn't have
> to make the keyboard work with an arbitrary length of USB.
I have an Apple Keyboard M9034/LLA that I bought when another user (no
names, please!) spilled orange juice on the one that originally came
with my iMac G5 (iSight). The replacement keyboard came with a USB
extension cable just as described above. Just as the OP was told, the
cable connector that goes into the USB socket on the rear of the iMac
has a linear depression on one side that mates with the bump on the
connector of the extension cable; however, the socket on the iMac has
no bump.
The original keyboard supplied with the iMac did not come with an
extension cable.
I have never had a use for the extension cable because the cable
molded onto the keyboard is 33 inches long, quite adequate for use
with the iMac sitting on the table behind the keyboard. The length of
the extension cable is about 39 inches (one meter, I suppose). If the
computer had been of the kind one might place on the floor, then the
extension might be necessary to use the keyboard on a table.
Matthew Russotto
The USB spec doesn't (or didn't) allow extension cables. The cable
actually works fine with other stuff if you force it or remove the
bump.
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