Apple has now begun shipping the 27" Thunderbolt Display that the company unveiled in July, and you can plug the 2560x1440 pixel display—which includes a complement of USB, FireWire, Ethernet, and Thunderbolt ports of its own—into any MacBook Pro, MacBook Air, Mac mini, or iMac released this year.
Apple has now begun shipping the 27" Thunderbolt Display that the company unveiled in July, and you can plug the 2560x1440 pixel display—which includes a complement of USB, FireWire, Ethernet, and Thunderbolt ports of its own—into any MacBook Pro, MacBook Air, Mac mini, or iMac released this year. Most Mac models support at least two external monitors with a few caveats—the most important being that you cannot daisy chain a Mini DisplayPort monitor to the Thunderbolt Display's Thunderbolt port.
The inclusion of the Thunderbolt port on Apple's Thunderbolt display is an important one, since all Thunderbolt-equipped Macs, save the 27" iMac, have just a single Thunderbolt port. That's not necessarily a bad thing, as a single port can daisy chain six devices. So if you plug a Thunderbolt Display into a Mac mini, for instance, you can plug a 12TB RAID into the back of the display and still have speedy access to its data.
It also makes it possible to use multiple external displays with an Apple notebook for the first time—at least without resorting to workarounds like USB video adapters. As we noted, the latest MacBook Airs use a smaller Eagle Ridge controller that only has one DisplayPort channel, so these machines are limited to just one Thunderbolt or miniDP display, period. The iMac, Mac mini, and MacBook Pro, on the other hand, use the Light Ridge controller with two DisplayPort channels. You can easily daisy chain two Thunderbolt Displays to a single Thunderbolt port on these machines.
There are a couple exceptions. The 13" MacBook Pro can only drive two displays total with its integrated Intel HD3000 graphics, so if you plug in two displays, the built-in screen will go black. On 15" and 17" MacBook Pros and iMacs, the main screen will continue to function. Despite having two Thunderbolt ports, the 27" iMac can still only use two external displays, regardless of whether they are daisy chained or plugged in to separate ports. (Though it has two ports, both are wired to a single Light Ridge controller, so there are only two DisplayPort channels total.) On the top-end Mac mini, which includes a discrete AMD Radeon GPU, you can plug in two Thunderbolt Displays and attach a third HDMI-compatible display to the HDMI port.
What is really going to rub folks the wrong way, we suspect, is that the Thunderbolt Display is not configured to work with a miniDP display plugged in to its Thunderbolt port. It wouldn't be surprising if more than one user with an existing 27" Cinema Display or other miniDP display got a Thunderbolt-equipped Mac and ordered a Thunderbolt display expecting to be able to add the miniDP display at the end of the chain.
Adding a miniDP display at the end of the chain works with other Thunderbolt peripherals that have downstream ports, so it's not a technical limitation of the spec. Why Apple added this limitation we cannot say, but it could be construed as a move designed to sell more $999 Thunderbolt displays. A more unfortunate side effect, we believe, is that not working according to the spec will add consumer confusion and hamper what is beginning to be a wider rollout of the technology in the PC industry.
