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#176 | ||
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![]() I've never had to "debug" a USB device. And frankly, "plugging it directly into the computer" would be both a step to debug a USB device and a Thunderbolt device. That step is meant to eliminate as many possible faulty ports in the link between the device and computer. That step is required in both a bus (daisy chain) and star (hub/switch) topologoies. Your post made absolutely no sense. Like Renzatic said, don't turn this into a Thunderbolt vs USB thing because Apple is suddenly pushing Thunderbolt. You're still allowed to like USB, even Intel says so : http://www.pcmag.com/article2/0,2817,2380890,00.asp Quote:
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"What you leave behind is not what is engraved in stone monuments, but what is woven into the lives of others." -- Pericles |
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#177 |
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#178 | ||
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With a daisy-chain, when you plug in a new device with a port to allow further chaining, you get one new device in the chain. USB doesn't allow this. If your device has more ports (even just one) to allow further devices, you'll get both the device you plugged in and a hub device in your 'chain'. In fact, most computers only have one USB bus, using a 'hub' device built into the motherboard to split that into all individual ports. Quote:
Yes, it's always possible that a device or hub has a bad port. Strangely, USB is the only bus I've dealt with where the *first* troubleshooting step is to change the port being used. That was never the first step with IDE, SCSI, SATA, Firewire, ADB. But thank you for being such an expert on debugging USB device issues, even though: We're all thankful for your innate, untested, yet infallible expertise. ![]() You should try rereading what I wrote for comprehension, because your response is mostly nonsense. (Though I commend your luck in never running into a USB peripheral which has issues running off a hub, or with another specific device in the chain.)
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17" MBP (unibody), 2.66GHz i7, 8GB RAM, 750 GB HDD; iPhone 4s 64GB/Black |
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#179 | |
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You may note that 90% of the CPU's I/O is reserved for graphics or display applications, and the PCH has 17.28 Gbit/s of FDI bandwidth but only 16 Gbit/s for the DMI (although the DMI is full-duplex). Furthermore, HD Graphics 4000 occupies 1/3 of the die area of an Ivy Bridge CPU. Display is clearly very important to Intel's customers. Do you find that the PCH on 2nd and 3rd gen Intel Core processor systems is crippled because it hosts a melange of I/O and display functions? How often do you think that users of these systems experience noticeable performance degradation due to DMI bottlenecking, despite having a front end that's more than 4.5 times as wide? Aside from those provided by the Port Ridge controller, all Thunderbolt ports can operate in two signaling modes: Thunderbolt (when it's connected to a Thunderbolt device), or DisplayPort compatibility mode (when it's connected to a conventional DisplayPort device). In Thunderbolt signaling mode, each link is comprised of two 10 Gbit/s, full-duplex channels. What types of packets (PCIe or DP) you choose to transport over those channels is entirely up to you. Each channel is wider than PCIe 1.0 x4 by 25%. I've pointed this out repeatedly, but it still doesn't seem to sink in; the only scenario in which DP packets limit PCIe bandwidth is when you're trying to write more than 8.4 Gbit/s of data to a Thunderbolt device daisy chained off of a pair of Apple Thunderbolt Displays. Reads simply cannot be impacted by DP, and the aforementioned situation can be avoided completely on any host system with more than one Thunderbolt port. Thunderbolt is clearly designed with the goal of relocating southbridge functions outside the box. The back end of a Thunderbolt controller is nearly identical to that of the PCH. 2x DisplayPort 1.1a is directly equivalent to FDI, and PCIe 2.0 x4 is the same as DMI 2.0 x4. I'll also take a moment to comment on daisy chain vs. tiered star topologies. You don't prefer daisy chains. That's legit and I get it. Thunderbolt can also be configured in a tiered star via switches. The silicon for those switches is not being produced, however, because there is no market for them. The retail cost would realistically be $100 or more per port, so a 6-port switch and one cable would cost $650, i.e absolutely prohibitive. Daisy chaining is the time honored solution for situations such as this. Parallel SCSI and IEEE 1394 are obvious examples, but perhaps you also recall the days when Ethernet hubs and switches were expensive enough that most small networks used 10BASE2, which was more or less the same theory. Thunderbolt is also distinct from those examples in that the nodes on the daisy chain are not connected via a shared bus. Essentially a 2-port Thunderbolt device contains what amounts to a 2-port (4-channel) switch. So the topology of a Thunderbolt chain is analogous to a chain of 4-port switches with 2 links between each switch. |
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#180 |
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If I were to take a guess as to why someone would be having problems with hubs on hubs on hubs, I'd say it's a power issue. If you've got an unpowered hub on a keyboard hooked up to a filled to capacity unpowered standalone hub that's hooked up to your computer, you're probably not getting enough power to run some of your devices on the keyboard. It's not a problem inherit to the design of USB specifically, you just need to plug the damn thing into an outlet somewhere.
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#181 | |
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USB daisy chaining never really took off though. More ports, reasonably priced hubs, etc. It just made more sense. It doesn't really make sense to Daisy chain USB. But, it CAN. Like another poster said, in the early days of home and small office networking, daisy chained network connections, or even a patch cable between just two computers was really common. Today though, you can buy a gigabit switch for $10 and EVERYONE has a Wi-Fi router, so Daisy chaining is dead in networking, for all practical purposes. We're back at 'square one' with thunderbolt. It's the latest high speed I/O, and it's new and expensive. In the future, better ways to connect multiple devices may come out (or may not! Never did with SCSI). However, I tend to think the latter. Simply because, with USB, there is NO reason to have MOST devices on thunderbolt. Displays, large and fast storage devices, and higher performance peripherals are all that should use thunderbolt. You wouldn't plug a mouse into thunderbolt, it'd be a total waste! Back in the days of SCSI, there were different ports for different tasks so it wasn't a big deal to daisy chain because only a handful of your most demanding devices used it. USB developed a need for hubs and such because it became the one port everything worked with. Everything I described in my SCSI chain had a USB version of some sort (even if not the same brands or models), however the mouse, keyboard, digital camera, etc. all became USB as well. I also used an external modem (connected to a special port on the Mac). Those became USB as well (though they were quickly replaced with cheaper internal modems and later broadband). So when EVERYTHING is using the same port, there is a need for hubs. USB is cheap, it works, everyone has it, it will remain king for most peripherals. Thunderbolt will be a standard used for displays (that use both the DP and the TB lanes), high speed storage (where a customer is willing to pay a premium for speed, as most people will be plenty satisfied with a drive running on USB 3.0, and that IS fine for most people), and perhaps some serious external devices. We're already seeing thunderbolt external fibrechannel connectors, PCI-E expansions, etc. There's even someone making a rack mount 'server' that uses a thunderbolt equipped mac mini inside a standard server enclosure. Then, the thunderbolt connects to PCI-E slots inside the enclosure, so you can connect your networking equipment. I honestly think Thunderbolt is the next generation of FireWire for most folks... high speed data used mostly by those willing to pay extra for the speed. For a select few others it may be realized as an external docking port, and I do hope that happens more and more, but right now that is pretty cost prohibitive for, ultimately, pretty mild features.
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Windows7 PC - Phenom II 965@4GHz x4 Cores, 4GB DDR3-2133, Radeon HD5870 | iPhone 5 32GB | iPad WiFi+3G 64GB | Mid 2012 MacBook Pro 13", Dual 256GB SSD's in RAID 0, 16GB DDR3-1600 |
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#182 | |
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Why would I need a laptop and a desktop? TB could give you both out of the same machine. And it's upgradeable! ...well, in about 4 years or so. Right now, the best use I can see out of it is hooking it up to a harddrive enclosure without sacrificing any speed. |
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#183 |
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I prefer mine than yours. After all, I've been dealing with USB for close to 14 years now. You seem to just have an "Apple is pushing Thunderbolt, so USB is bad!" attitude.
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"What you leave behind is not what is engraved in stone monuments, but what is woven into the lives of others." -- Pericles |
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#184 | |
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There is still a need for a desktop, but for many of us, 90% of our workload is now on our laptops. For some, that could be increased to 99 or 100% with Thunderbolt being realized to add functionality to the machine. It won't be perfect, but it's already been demonstrated as working quite well. MSi is the latest to join the unfortunately vaporware PCI express dock crowd. However, they demonstrated a GPU mounted in a thunderbolt enclosure and ran graphics benchmarks significantly faster than what was built into the MBP. For the right price point, and daisy chained with a thunderbolt dock that allows you to connect your other peripherals and such? Very cool. Some will gripe that the MSi Gus can't handle the bigger cards, but TB isn't fast enough for that anyway. But it IS fast enough to give mid range or better desktop level graphics to a MacBook Air or MacBook Pro, and I think that's cool! The reason I think that's cool is I have a couple large IPS displays. One of them is an Apple Cinema Display. I have no way to connect more than one display to my computer. I could buy a couple very expensive thunderbolt displays, OR, I could hook into a 'docking station' that included a PCI-E slot, and thus a graphics card capable of driving all my displays, that would cost less than a single thunderbolt display, and be golden! I'd also get all my firewire devices and such all fired up and ready to go, with one cable. It's a-comin. I think ThunderBolt is going to reign king in the mobile market for that reason. We shall see!
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Windows7 PC - Phenom II 965@4GHz x4 Cores, 4GB DDR3-2133, Radeon HD5870 | iPhone 5 32GB | iPad WiFi+3G 64GB | Mid 2012 MacBook Pro 13", Dual 256GB SSD's in RAID 0, 16GB DDR3-1600 |
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#185 | |||
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Then again, most 'unpowered' hubs are simply hubs sold without their power supply. It's a way for the company to save some money. ---------- Quote:
In a daisy chain, the bus passes through the device from one port to the other, with the device hanging off in between. There's no hub device. USB doesn't allow that. It allows 'up to 127' devices off a single bus. (Actually 128, but one of those devices is the USB controller in the computer.) In practice, you can only hang up to 125 USB devices off a typical computer because all of the external ports are split off from a single bus with an internal 'hub' (which is a device), and you'd need a single 125-port hub to get the rest of the devices plugged in without other hubs taking up more of those potential device 'slots'. The devices you're talking about with a single input port and a single output port are simply devices with a built in 2-port hub. One of the 'ports' is permanently wired to the device, the other is exposed on the back of the device. If you were to look at your device chain when you plugged that scanner into your computer, you'd see: Computer -> USB Controller -> Hub (to split the single bus into multiple physical ports) -> Hub (this one is built into the scanner) -> Scanner That's a star topology, not a daisy-chain. You just don't have enough devices plugged in to make it physically apparent, and you've got an 'invisible' hub. ---------- Quote:
Your own biases do not come from me.
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17" MBP (unibody), 2.66GHz i7, 8GB RAM, 750 GB HDD; iPhone 4s 64GB/Black |
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#186 | |||
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The chipset doesn't support 4 graphics devices, so what do you do about the graphics channel on the 3rd/4th T-Bolt connector? That's the problem. If T-Bolt were PCIe extender only - no problem. Quote:
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US President urges Supreme Court to strike down Prop. 8 and DOMA All the cool guys have Jony Ive avatars, so I found one too. The goatee is much sexier than the Yul Brynner look. |
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#187 | ||
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What does limit the number of Thunderbolt ports on a device is their power requirement. The upper bound on performance is really just TDP. Take Titan, for example: 17.59 petaFLOPS using just AMD Opterons and NVIDIA Teslas, but it consumes 8.2MW in the process. The volume of a device determines the acceptable range of TDP. From there, you can try to increase performance per watt as much as possible, or make trade-offs in terms of battery life or mass. Apple generally leads the industry by a healthy margin when it comes to meaningful performance per liter (the current Mac Pro situation notwithstanding). The 15-inch MBPs can be specced with up to a 3820QM, the fastest processor Intel makes under 50W, so I can't imagine it's CPU "performance" that you're complaining about. They also have more I/O bandwidth than any other notebook on the market by miles, so I guess it's just the NVIDIA GeForce GT 650M that doesn't meet with your satisfaction. Well, if you're looking for workstation class graphics or dual GTX 680Ms in SLI for gaming, then no, Apple doesn't go there. The largest notebook in Apple's lineup is also right around 2 liters and weighs in at 5.6 lbs., with the Retina version being only 1.5 liters and 4.46 lbs. If you'd care to show me some "performance" laptops that offer more performance per watt, more performance per liter, or offer even comparable performance, battery life and thermals in the same size package, I'd love to see them. SUVs aren't higher performance cars, they're just bigger, uglier and less efficient/worse for the environment. Quote:
1.) All Thunderbolt devices are port-blocking. This keeps the cost of devices to a minimum, but only allows for the connection of as many devices as the host has ports. 2.) Create a Thunderbolt controller with an embedded 2-port switch so that non-blocking devices can be made which allow for daisy chaining up to 6 devices off of a single host port. 2-port devices will retail for approximately $100 more than the equivalent port-blocking version. 3.) All Thunderbolt devices are port-blocking, however, you also produce and market a Thunderbolt switch that allows for tiered-star topologies. These would offer 5-8 ports and retail for about $550-$850. If a consumer does not buy a switch, they can only connect as many devices as their host has ports. 4.) Go with option #2, but also produce a switch once the market has gained sufficient maturity and the economics of doing so are justifiable. You have chosen option #5, offer no practical solution due to a fear of daisy-chains resulting from some horrible experience at some point in your life. The only devices which present additional complexity in a daisy chain vs. a tiered-star are storage devices, everything else can be hot-plugged just fine. Before being disconnected, external storage volumes directly connected to a host port still need to be properly unmounted, or, in the case of boot volumes, the system needs to be shut down. The same applies to all volumes connected via a hub or switch if you need to disconnect that hub or switch. The only time daisy chains become annoying is if you are forced to position boot volumes or volumes that cannot be conveniently unmounted towards the end of a chain, or a device in the chain loses power and disconnects all the devices further down the line. Obviously these situations are only partially mitigated in a tiered-star. Is there something I'm missing that triggers your Gordon Ramsay style reaction? Last edited by repoman27; Jan 7, 2013 at 12:45 PM. |
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#188 | |
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Just let it go. USB is ubiquitous, cheap and compatible. It's a good piece of design and the proof is in the pudding, it's still with us, 14 years later (if not more).
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"What you leave behind is not what is engraved in stone monuments, but what is woven into the lives of others." -- Pericles |
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#189 |
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Too little, too late.
Perhaps it was delayed by Apple's obsession with legal attacks on the competition, only to find that it may have generated enough bad karma to hurt them. Even though the effects are not obvious at the present moment, you get back what you put out. All that negative, vitriolic toxicity didn't do much for Apple. |
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#190 | |
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#191 |
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Nope, I'm not. The poster was alluding to general USB problems, all versions included. Not a specific issue you seem to point out again and again.
Rest of your post is completely off-context for our sub-thread.
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"What you leave behind is not what is engraved in stone monuments, but what is woven into the lives of others." -- Pericles |
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#192 | |
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17" MBP (unibody), 2.66GHz i7, 8GB RAM, 750 GB HDD; iPhone 4s 64GB/Black |
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#193 |
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Is there any information available on the fiber specification for thunderbolt?
I found an article than mentioned it works with standard multimode 850nm duplex cable but is 50 or 62.5um? Last edited by diddl14; Jan 13, 2013 at 09:30 AM. |
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#194 |
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Seriously they should just give it up. The Thunderbolt industry failed to deliver, even after years of waiting they still don't have what they promised. So what if 0.05% of the public has benefitted from it, I'd still benefit more from another USB port or being able to output video without having to resort to an adapter.
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OS X Lion speaker icon gray on Menu Bar workaround. |
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#195 | |
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Also, your argument is completely self-entitled and inept. Given this is Apple, you would have had to used an video adapter no matter what... What do you think mini-display port was?
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Mac Mini (i7, Late 2012), iPhone 5 (32GB), iPad Mini (32GB), Thunderbolt Display |
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#196 | |
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USB is a universal serial bus (hence the name). It's a bus designed to connect virtually anything. It can handle basic networking between computers, or more advanced networking with adapters plugged into it. It can handle peripherals, storage devices, etc. Thunderbolt is meant to be an ultra-fast connector for specialty applications; like high speed storage. Besides, it's only been a couple years! It was nearly a decade before USB really took off! Even so, it'll never dethrone USB; but it does two things USB doesn't do; 1) It provides blindingly fast speeds and a direct connection to the PCI-e bus. 2) It provides CONSISTENT speed. One of the most ANNOYING things about the USB standard is that they flat out LIE with their speeds. Even the USB standard, in the fine print, isn't CAPABLE of hitting 5gbps. It's just that the electrical connectors and cables are 'theoretically' capable of hitting it. The realistic a speed a user should expect, per Intel and the standard, is around 2.4gbps, or roughly HALF of the 'advertised' speed. Wheras thunderbolt, is in fact, capable of a full 10gbps. It's been that way forever. A classic example is how FireWire 400 (400mbps advertised) was about twice as fast transferring data as USB 2.0 (480mbps advertised).
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Windows7 PC - Phenom II 965@4GHz x4 Cores, 4GB DDR3-2133, Radeon HD5870 | iPhone 5 32GB | iPad WiFi+3G 64GB | Mid 2012 MacBook Pro 13", Dual 256GB SSD's in RAID 0, 16GB DDR3-1600 |
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#197 | |
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Please support your "twice as fast" claim before we believe anything else in your post. In my experience (using external drives with both USB 2.0 and 1394(a)), I'd see a bit more than 30 MB/sec using the USB interface, and a bit less than 35 MB/sec using 1394. Anandtech even showed USB 2.0 beating 1394. ![]()
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US President urges Supreme Court to strike down Prop. 8 and DOMA All the cool guys have Jony Ive avatars, so I found one too. The goatee is much sexier than the Yul Brynner look. |
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#198 | ||
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Also your definition of fast using bandwidth figures are also inaccurate. Data bandwidth is different from data connection speeds.
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OS X Lion speaker icon gray on Menu Bar workaround. |
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Your own biases do not come from me.


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