M1 Macs have two Thunderbolt ports, **but** each on its own bus!

TidBITS posted a very interested find:
Thunderbolt Improvements in the M1-Based Macs:

…the new Macs have only two Thunderbolt ports, compared to four on the Intel-based 13-inch MacBook Pro and Mac mini, [SoftRAID developer Tim] Standing discovered that each port has its own Thunderbolt bus.

Emphasis mine!

By comparison, each pair of Thunderbolt ports on the Intel-based Macs share a bus, meaning that they also share bandwidth. If you plug two fast drives into ports that share a bus, performance suffers.

Standing also notes that the M1-based Macs have Thunderbolt 4, which differs from Apple’s implementation of Thunderbolt 3 in only one fundamental way: Thunderbolt 4 adds support for Thunderbolt hubs that let you add more ports.

To read the original article (linked from TidBITS) go here:
Thunderbolt on the M1 Mac mini – When 2 Actually Does Equal 4


Ummmm… Standing claims the M1 Macs have Thunderbolt 4 but Apple’s Tech Specs list the ports as Thunderbolt 3 / USB 4. (In reality that means USB 3.1 Gen 2) Isn’t Thunderbolt 4 still off in the future/

MY QUESTION: So does this mean the ports are NOT separate ports???

How did his article make it past Editors?


The article does not say that they are Thunderport 4. It just says that Apple has implemented much of what will be in Thunderport 4 already in Thunderbolt 3. In Thunderbolt 3 these specification are “optional”. I have no actual knowledge of the details of any of this but Standing is not claiming that M1 Mac have an actual Thunderbolt 4 as I read the article.


So the claim is separate buses - so more bandwidth. Some enterprising people might make mini hubs that plug in each side of the machine. (I’ve not got an M1 Mac so don’t know if the ports are on opposite sides.)

Regarding Thunderbolt 4 certification for Apple Silicon Macs - there is one requirement that explains why Apple’s Thunderbolt ports are not certified as Thunderbolt 4:

Required Intel VT-d-based direct memory access (DMA) protection that helps prevent physical DMA attacks.

So, technically a Thunderbolt 4 certification requires Intel hardware (which might change eventually).

But… What is Thunderbolt 4 apart from that according to Intel?

  • Double the minimum video and data requirements of Thunderbolt 3.
  • Video: Support for two 4K displays or one 8K display.
  • Data: PCIe at 32 Gbps for storage speeds up to 3,000 MBps.
  • Support for docks with up to four Thunderbolt 4 ports.
  • PC charging on at least one computer port. (For thin-and-light laptops that require less than 100 watts to charge.)
  • Wake your computer from sleep by touching the keyboard or mouse when connected to a Thunderbolt dock.

So, basically everything Apple is doing already. Or am I missing something? :slight_smile:

To cite OWC:

Thunderbolt 4 finally promises PC/Windows users all the features Thunderbolt 3 has long offered Apple users. For Mac users, full Thunderbolt capability has always been present. This has been true since the first Macs with Thunderbolt 3 (Thunderbolt USB-C).

Source: https://other-world-computing-press-room.prezly.com/owc-explains-what-is-apples-thunderbolt--usb-4-vs-pc-windows-thunderbolt-4

And yes, there will be a new OWC Thunderbolt hub available soon:wink:


Some useful background info here.

and the OWC offering (shipping mid-December 2020) mentioned in the release that @Christian quoted:

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Well, for one thing the current M1 Mac laptops only support one display (though we don’t know if this is a limitation of Apple’s Thunderbolt implementation or some other part of the system).


Yes, I missed that. My bad.

A crazy guy has managed to run some more displays using his M1 Mac, though:

Not a real solution, but I think that we will hear from Apple about multiple displays on an Apple Mx Mac - maybe even with a M1? One can dream.

Man, it is hard to watch all this M1 stuff without jumping on the Apple Silicon train… :wink:

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I have to keep telling myself “wait for Silicon gen 2, wait for gen 2, wait…”


Exactly like that. Exactly like that! :blush::laughing:

Maybe, I will have to skip the next MPU episodes now that @MacSparky has entered the M1 world, too:

La-la-la! La-la-la! I don’t hear anything! Nothing. My Intel Mac is just great. It is the greatest Mac I ever owned! Unprecedented. Designed by Jonny Ive in the white cloud. 400 gazillion times faster than any Mac that is 10 years old… :wink:


From the article: “Standing also notes that the M1-based Macs have Thunderbolt 4, which differs from Apple’s implementation of Thunderbolt 3 in only one fundamental way: Thunderbolt 4 adds support for Thunderbolt hubs that let you add more ports.”

Now if the fact that Thunderbolt 4 requires Intel to be certified as such… then Apple is probably using a “CYA” method in their marketing.

I love my 2018 Mac Mini and keep fighting the urge to upgrade to M1. But if they offer it in Space Gray, I will crumble in a heartbeat.

CYA as in this CYA context? Sorry for my potential lack of English in this case.

If so - yes, that could be the case. In the mentioned article “Thunderbolt 4” is being called like that by Tim Standing, developer of SoftRAID. As far as I understand it, Apple does not refer to the M1 Thunderbolt ports as Thunderbolt 4, but as Thunderbolt / USB 4, which is confusing and funny at the same time because the “4” is being mentioned, but it technically refers to its USB capability. I am quite sure that they have done this deliberately. :slight_smile:

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What do you think I will get?

M1 and buy this usb hub https://www.transcend-info.com/Products/No-1058


Macbook pro 2019 and buy 2pcs thunderbolt3 to usb adaptor
Since it has 4 usb c ports.

Btw it is both 2nd hand and at the same price.

What will I choose?

I will use it for data wrangling works

Mostly I need 2 usb for camera card reader and for external hdd both use at the same time

If you can hold out for two more months, I’d wait for the rumored new MacBook Pro.

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Definitely wait if you can wait. I’d expect that Apple will announce new hardware (if any) by the end of October.