Pricey Apple Thunderbolt cable inner chippery exposed
40 quid for wires... and 12 chips
Want to know why Apple is charging £39 - $50 in the US - for its Thunderbolt cable?
For once it's not entirely the company's price-high-for-fanboys policy - the cable is an active transmitter.
Apple's Thunderbolt cable: on the outside...
The kit disassemblers at iFixit.com have found that the cable, which connects Macs to peripherals using Intel's new high-speed - two independent channels of 10Gb/s each - bus, contains rather more chippery than you'd see in your average cord.
...and on the inside
Source: iFixit.com
There are six chips at either end of the cable, but the grunt work is done by two of chip-maker Gennum's cable-oriented GN2033 Thunderbolt transceivers.
Essentially, these boys and the supporting parts ensure the 2m of wiring - 3m is the max - in between don't attenuate the signal so far that the data transfer speed plunges.
All this means that the cable is also powered - for the chips, if not the external device. Thunderbolt muxes PCI Express bus data and DisplayPort traffic then separates them out at the other end. ®
COMMENTS
Why...
...isn't all that gubbins in the port where it belongs?
Because...
...the port can also handle forthcoming optical cables - and the "gubbins" for sending and receiving the optical signal is also in the cable. If the gubbins were in the port the port would not be compatible with optical cables and you'd be whining about that instead.
Read up on the subject.
I think...
...Those pictures are of the gubbins inside one end of the cable, viewed from either side, hence the different numbers on the transducer chips.
How is it not their fault?
If a new protocol isn't reliable enough to run over 2 metres of cable without expensive circuitry then the thing is broken. That's not surprising seeing as Light Peak was supposed to use fibreoptic cable originally and ended up using copper and was gimped in other ways. Presumably if the system had been optical as promised the cable could have been 10 metres in length and still worked.
Apple shouldn't have included the tech at all in its current state.
What am I missing?
Why not simply add those chips to the port on the computer and peripheral and use a passive cable? What are the benefits of this?
