2019 Mac Pro and Pro Display XDR: Big Iron for Big Bucks

Originally published at: https://tidbits.com/2019/12/10/2019-mac-pro-and-pro-display-xdr-big-iron-for-big-bucks/

As promised, Apple has released the powerful Mac Pro and Pro Display XDR before the end of 2019. Not by a lot, but if you get your order in soon, Apple will even deliver them before January. Just be prepared to pony up a chunk of change.

The use of USB-C rather than Thunderbolt 3 feels odd, given that Thunderbolt 3 supports daisy-chaining of devices, but the current iPad Pro models have USB-C ports, and the iPhone 11 Pro models come with a USB-C to Lightning charging cable.

To me that doesn’t make any sense. TB3 supports USB-C charging just fine so had all ports been TB3 iPads and iPhone 11 Pro would have charged the same.

Choosing USB-C over TB3 for the extra ports is of no advantage to users. Quite the opposite. A pair of TB3 (or even TB3 for all 4) would have added a lot of extra flexibility. At the price Apple’s charging for this display, there was zero reason to skimp on any connectivity specs.

That was my sense as well—I can’t really understand why Apple would change ports in the same piece of hardware. USB-C just doesn’t have any advantage over Thunderbolt 3 as far as I know.

As I understand it you can’t just take a TB3 port and break it out into 3 more TB3 ports. The usual arrangement is to have a TB3 passthrough (single TB3 in, single out) or just have a single TB3 for upstream connection. Is there such a thing as a TB3 -> multiple TB3?

Good question, and I don’t know the answer. I’m mostly surprised that there isn’t one Thunderbolt 3 port done as a passthrough/daisy chain—that should be possible, regardless. And if Apple was clever, there could be three more Thunderbolt 3 ports, but the Pro Display XDR would support only one Thunderbolt 3 device at a time, forcing the other two ports to fall back to USB-C. But maybe that’s just fantasy.

This isn’t rocket science. Apple’s old TB display connected through Thunderbolt upstream and still offered an additional TB port for downstream. This new screen has one TB port for the upstream connection and nothing left for downstream but USB-C. Welcome to pre-2011.

The only technical issue I could imagine right now is that the display data itself requires so much of the TB3 bandwidth, there is simply nothing left for passthrough to a downstream port. I have, however, not read anything to that effect so far. And the three USB-C downstream ports seem to indicate there is ample bandwidth left (3x ~10 Gbps).

Not that I’ve ever come across. The same has been true since TB1, allowing only pass-through daisy-chaining.