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USB4 Specification Announced: Adopting Thunderbolt 3 Protocol for 40 Gbps USB

anandtech.com

131–140 of 279 posts

Re: USB4 Specification Announced: Adopting Thunderbolt 3 Protocol for 40 Gbps USB

#131

Is it an unpopular opinion that USB is already fast enough and has enough features and USB implementers should instead work on cost reduction and compatibility so that we can all move away from USB 2 and pre-type-C connectors?

USB is already fast enough for all the things we've traditionally used USB for: wifi, mice, audio, smartphones, printers, thumb drives, HDDs, etc.

It's not fast enough for next generation use cases: external displays, eGPUs, or modern SSDs.

Re: USB4 Specification Announced: Adopting Thunderbolt 3 Protocol for 40 Gbps USB

#132
post #114

Earlier quoted context omitted.

So remind me, why can you walk into any apple store, pick up a new MacBook and a 5K LG monitor, and when you plug in the monitor using the USB-C cable that was bundled with the MacBook it just won't work at all? My point is - the standards might be back and forward compatible. But the cables and ports definitely aren't - and your average consumer has absolutely no way of knowing. They look absolutely identical on the…

No wiring issues necessary; the MacBook just isn't powerful enough to drive a 5K display. (I think the question you meant to ask is why the MacBook can't drive an external 4K Thunderbolt display using its included cable, which is more interesting—IIRC, it can do so through an HDMI adapter plugged into the USB-C port, but it cannot do so over a USB-C cable. This still isn't about the cable, though; you can take the Ma…

Uhm....you can definitely connect the LG 5K UltraFine display to the latest MacBook using the USB-C(TB3) cable included with the monitor and it will work(and even charge the MacBook at the same time). So the MacBook definitely has enough power to drive it. But if you use the cable that was bundled with the MacBook it won't work even though externally it looks the same and will fit ports on each side.

Less extreme example is how the OnePlus USB-C charger won't charge the Nintendo Switch, even though they are both USB-C certified devices.

Edit: sorry, I just realized that I could have been misunderstood. I forgot that "MacBook" is a device that exists. Obviously(to me) by MacBook I mean the MacBook Pro.

Re: USB4 Specification Announced: Adopting Thunderbolt 3 Protocol for 40 Gbps USB

#133
post #90

Earlier quoted context omitted.

Thunderbolt is PCIe so instead of a backplane you can use a cable. So basically anything you'd use PCIe for (drives, external GPUs etc) you can use TB for.

Not quite, because the equivalent pure pcie connection is faster than thunderbolt due to the overhead in thunderbolt. We need another doubling in thunderbolt's speed for it to not have a penalty when using eGPUs

It's been a few years since I was programming those things but IIRC the TB 3frames are comparable to PCIe 3 frames (terminology is slightly different between the two).

The real thing is that TB3 only has four lanes while Intel's server (and I believe some desktop) chipsets have 16-lane PCIe. Not sure about the mobile chipsets (again, I no longer follow this as closely/ as I used to). So indeed you won't be able to pump data into an eGPU as quickly as you could a high performance internal one. Or perhaps we should add "yet"?

Re: USB4 Specification Announced: Adopting Thunderbolt 3 Protocol for 40 Gbps USB

#134
post #122

Earlier quoted context omitted.

> With USB 3.0 they added 4 more signals for separate transmit/receive So is it not actually serial any more?

It's a low-speed differential pair that negotiates the initial communication. Once the bus knows it can go to a faster speed, it will switch to a separate receive differential pair and transmit differential pair. -Power -Ground -Signal Ground -USB2 data+ -USB2 data- -USB3 RX+ -USB3 RX- -USB3 TX+ -USB3 TX- So it's a slow serial bus that negotiates traffic onto a faster serial bus. https://en.wikipedia.org/wiki/USB_3.0…

> It's a low-speed differential pair that negotiates the initial communication.

AFAIK, it's not, the SuperSpeed (USB3) wires have their own independent negotiation; the device switches to the USB2 wires only when USB3 is not detected. This also explains how the proposed VirtualLink alternate mode can have USB3 without the USB2 pair.

Re: USB4 Specification Announced: Adopting Thunderbolt 3 Protocol for 40 Gbps USB

#135
post #88

I'd be curious about 40Gbps for what cable length. TB3 is great, you can in theory dock a laptop with a single cable that will do charging, 10gbe, USB hub, etc, but with a max 50cm cable, which makes it quite "un-lappable". I'd love to do the same with a 2m cable.

CalDigit makes a 2m 100W TB3 cable. No backwards USB compatibility though, it's only Thunderbolt.

Re: USB4 Specification Announced: Adopting Thunderbolt 3 Protocol for 40 Gbps USB

#136

Earlier quoted context omitted.

The cables should have a ss or ss 10 or ss 20 label on them. The end devices should too I believe.

Apple cables and ports have no logos on them whatsoever. Just plain white/silver if metal.

Not true. See their thunderbolt cables: https://www.apple.com/shop/product/MD861LL/A/apple-thunderbo...

Re: USB4 Specification Announced: Adopting Thunderbolt 3 Protocol for 40 Gbps USB

#138
post #59

Honestly, I'm waiting for old USB(USB A, USB B) to be deprecated and USB C become the new universal USB. As in ATM machine, you get the drill. Current USB cable situation is a mess - my phone is USB C, but it came with a USB A to USB C cable. Good thing I can connect it to my 2017 MacbookPro using it's original USB C charging cable! However then I can't charge. Sometimes I use a USB C to female USB A dongle to use my…

> good USB C cables seem to be made out of gold USB type C cables are active (they have silicon in them and handshake themselves with the host rather than simply being wire (possibly plus a resistor) as with old USB cables.) Cost will come down as volume goes up. Currently the only way to buy a cheaper cable is to buy a noncompliant and possibly dangerous one. > Life would become so much easier if everything was USB…

Most of the cables aren't going to have anything more than a few-cent chip that lists the capabilities.

Re: USB4 Specification Announced: Adopting Thunderbolt 3 Protocol for 40 Gbps USB

#139

Earlier quoted context omitted.

Apple cables and ports have no logos on them whatsoever. Just plain white/silver if metal.

Not true. See their thunderbolt cables: https://www.apple.com/shop/product/MD861LL/A/apple-thunderbo...

Fair enough. But their USB-C cables and chargers do not:

https://www.apple.com/uk/shop/product/MLL82ZM/A/usb-c-charge...

Re: USB4 Specification Announced: Adopting Thunderbolt 3 Protocol for 40 Gbps USB

#140
post #67
post #14

Earlier quoted context omitted.

My hope is that Type-C is going to be all of those things so that in the future, I only need one kind of cable (until the inevitable new plug that supplants it, but hopefully universally used as well). Currently, I have to pay attention to a USB3 Type-C cable vs a Thunderbolt 3 cable as there is a difference (I was shopping for a long TB3 cable and was unable to find one. Instead, seems the longer ones tend to be USB…

This is not a realistic expectation, unless you are OK with your "one cable" being 0.5m long. The "one-cable" thing is a dream, unfortunately.

As long as the only difference between cable capabilities is speed, I'm happy. We're not quite there but we're close.

Also it would need to be marked on the cable somewhere.

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