Domain: usb.org
Stories and comments across the archive that link to usb.org.
Comments · 233
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Re:long awaited replacement to RS-232?
USB can't do it since it requires a computer
Not any more with "USB On-The-Go" which does not require a host to create a link over USB. Of course, you would need a USB chip that understands USB-OTG... that would eliminate the need of a host. -
Re:This is hilarious!Here's the paragraph you quote (which is why we're having this discussion): "The USB 2.0 specification requires hubs to support high-speed mode. USB 2.0 devices are not required to support high-speed mode. A high-speed capable upstream facing transceiver must not support low-speed signaling mode. A USB 2.0 downstream facing transceiver must support high-speed, full-speed, and low-speed modes." [emphasis mine.]
So. Hubs must support high-speed, and downstream-facing transceivers (which I understand to mean "host" interfaces) must support high-, full-, and low-speeds, and yet USB 2.0 devices (not hubs and not hosts) do not have to support high-speed. But I'm certainly not sure what differentiates a USB 2.0 full-speed device from a USB 1.1 full-speed device. If a device is claimed to be USB 2.0 full-speed, what precisely would make it different from a USB 1.1 full-speed device?
I still find it most interesting that this is in direct contradiction with their earlier documentation. This whitepaper on their site consistently refers to USB 2.0 devices (functions, not just hubs and hosts) as high speed.
That promise went everywhere. The understanding was universal. The USB-IF themselves told us that forthcoming USB 2.0 == high speed. But that one line in the spec breaks the promise. It's not consistent.
I understand backward compatibility. And I think your argument is that they are trying to keep only one spec current, USB 2.0, and that by permitting low- and full- speed devices to be made under that same spec they're allowing legacy equipment to continue to be made and sold. But to allow full-speed equipment to be marketed under the "USB 2.0" spec when that industry told us long ago that "USB 2.0 means 480 Mb/s" is deceptive. That's the problem.
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They're renaming
The way I see it, it looks as if they whan to go away from the numbering of USB standards, and instead introduce a speed label, i.e. 'low speed', 'full speed' or 'hi-speed'. So in stead of going out shopping for a laptop with USB 2.0, they want you to look for one with Hi-Speed USB.
I think it's pretty obvious when you look at the logos on the USB Packaging page.
The problem with this naming scheme is of course, that they have to come up with new and more impressive names for each new version of USB. I expect that the standard computer in 2015 will support USB eXtra Fast Super Ludicrous Hi-Speed.
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Where exactly does USB 1.1 get renamed to USB2?The article & fevered imaginations of Gareth Powell aside, can anyone point me to an example (or recommendation) of calling a USB 1.1 device "USB2"?
This page specifically recommends against calling USB 1.1 devices "USB 2.0" as it "can be confusing for consumers whose expectation is that a USB 2.0 product is by definition high-speed."
Of course, they do say it's OK to call USB 1.1 "USB Full Speed" (which is historically valid but misleading these days), or to describe them as "USB 2.0 compatible" (not "compliant", but nonetheless clearly misleading), but I still don't see where, as the article claims, the USB Forum announced that "henceforth USB 1.1 would be called USB 2".
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Re:This is hilarious!I fail to understand your argument.
To your point, "I really don't see what the big deal is if people realize that USB 2.0 != high speed (480 MBit/sec)," it's the entire point of the argument. People DON'T realize that because it's simply not true. The phrase USB 2.0 has already come to mean high speed through usage; usage both defined and fostered by the very same usb.org. Doubt me? Here's what the usb.org has on the first page of "A Technical Introduction to USB 2.0" describing USB 2.0 [formatting from the original, emphasis mine ]:
"USB 2.0 Executive Summary
A core team from Compaq, Hewlett Packard, Intel, Lucent, Microsoft, NEC and Philips is leading the development of the USB Specification, version 2.0, that will increase data throughput by a factor of 40. This backwards-compatible extension of the USB 1.1 specification uses the same cables, connectors and software interfaces so the user will see no change in the usage model. They will, however, benefit from an additional range of higher performance peripherals, such as video-conferencing cameras, next-generation scanners and printers, and fast storage devices, with the same ease-of-use features as todayâ(TM)s USB peripherals.Impact to User
From a userâ(TM)s perspective, USB 2.0 is just like USB, but with much higher bandwidth. It will look the same and behave the same, but with a larger choice of more interesting, higher performance devices available. Also, all of the USB peripherals the user has already purchased will work in a USB 2.0-capable system."Contrast that statement with this quote from the USB Naming and Packaging page:
"Inconsistent use of terminology in combination with the existing general misconception that USB 2.0 is synonymous with Hi-Speed USB
... creates confusion in the marketplace."So you can now see why we've our little tempest in the proverbial teapot. Even the USB organization themselves used the specific words "USB 2.0" to precisely mean the exact same thing they now call "Hi-Speed USB" -- 480MB/s USB. And then they tell us that we, the marketplace, suffer confusion from a misconception. If they aren't fostering that confusion, who else is?
My biggest complaint is that their packaging page permits manufacturers to label their "Low-Speed USB" or "Full-Speed USB" products with these statements:
- 1. Compatible with the USB 2.0 Specification
- 2. Works with USB and Hi-Speed USB systems, peripherals and cables.
/. Also note that the only speed mentioned in these statements is "Hi-Speed". This is the marketing they encourage vendors to put on their "Low-" and "Full-" speed USB devices, but nowhere on the package is it required to state "Low-Speed" or "Full-Speed".This is the stuff of "truth in advertising" lawsuits. IANAL, because if I were I wouldn't be ranting on
/., I'd be cranking up a lawsuit.And just to keep going, if your other statement were true, "A USB 1.1 compliant device can meet the specification even if it only supports low speed operation (1.5 MBit/sec)," then I should be able to claim my 300 baud acoustically-coupled modem made in 1978 is "V_fast" compliant just because the V_fast spec says a V_fast modem must accept connections from 300 baud modems. Receiving an honorable mention in the spec does not mean it meets the spec.
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Re:This is hilarious!I fail to understand your argument.
To your point, "I really don't see what the big deal is if people realize that USB 2.0 != high speed (480 MBit/sec)," it's the entire point of the argument. People DON'T realize that because it's simply not true. The phrase USB 2.0 has already come to mean high speed through usage; usage both defined and fostered by the very same usb.org. Doubt me? Here's what the usb.org has on the first page of "A Technical Introduction to USB 2.0" describing USB 2.0 [formatting from the original, emphasis mine ]:
"USB 2.0 Executive Summary
A core team from Compaq, Hewlett Packard, Intel, Lucent, Microsoft, NEC and Philips is leading the development of the USB Specification, version 2.0, that will increase data throughput by a factor of 40. This backwards-compatible extension of the USB 1.1 specification uses the same cables, connectors and software interfaces so the user will see no change in the usage model. They will, however, benefit from an additional range of higher performance peripherals, such as video-conferencing cameras, next-generation scanners and printers, and fast storage devices, with the same ease-of-use features as todayâ(TM)s USB peripherals.Impact to User
From a userâ(TM)s perspective, USB 2.0 is just like USB, but with much higher bandwidth. It will look the same and behave the same, but with a larger choice of more interesting, higher performance devices available. Also, all of the USB peripherals the user has already purchased will work in a USB 2.0-capable system."Contrast that statement with this quote from the USB Naming and Packaging page:
"Inconsistent use of terminology in combination with the existing general misconception that USB 2.0 is synonymous with Hi-Speed USB
... creates confusion in the marketplace."So you can now see why we've our little tempest in the proverbial teapot. Even the USB organization themselves used the specific words "USB 2.0" to precisely mean the exact same thing they now call "Hi-Speed USB" -- 480MB/s USB. And then they tell us that we, the marketplace, suffer confusion from a misconception. If they aren't fostering that confusion, who else is?
My biggest complaint is that their packaging page permits manufacturers to label their "Low-Speed USB" or "Full-Speed USB" products with these statements:
- 1. Compatible with the USB 2.0 Specification
- 2. Works with USB and Hi-Speed USB systems, peripherals and cables.
/. Also note that the only speed mentioned in these statements is "Hi-Speed". This is the marketing they encourage vendors to put on their "Low-" and "Full-" speed USB devices, but nowhere on the package is it required to state "Low-Speed" or "Full-Speed".This is the stuff of "truth in advertising" lawsuits. IANAL, because if I were I wouldn't be ranting on
/., I'd be cranking up a lawsuit.And just to keep going, if your other statement were true, "A USB 1.1 compliant device can meet the specification even if it only supports low speed operation (1.5 MBit/sec)," then I should be able to claim my 300 baud acoustically-coupled modem made in 1978 is "V_fast" compliant just because the V_fast spec says a V_fast modem must accept connections from 300 baud modems. Receiving an honorable mention in the spec does not mean it meets the spec.
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Real marketing...
I haven't heard any news about this, and I have several gripes with this story:
First off, the article mentioned that USB1.1 had been changed to USB2, while leaving USB2 the same. Referencing the USB Implementers Forum website referenced by the article at http://www.usb.org, I couldn't find a single reference to USB 2.0. Seems USB 1.1 has been renamed "Original USB" where USB 2.0 is "Hi-Speed USB." (Check the FAQ under the question "How fast is USB?") This is an awfully big difference from what the article purports.
Secondly, I think most reputable manufacturers of hardware components to those who build their own PCs, such as motherboard chipsets, add-in USB2 (ha!) cards, etc. would maintain the older numbering scheme so as not to confuse their target market.
I think the source of this article's confusion comes from devices marked "Hi-Speed USB 2.0." Apparently this labeling scheme is supposed to combine the "USB 2.0" that older enthusiasts are familiar with, with the "Hi-Speed USB" that the USB Implementers Forum is pushing now.
Doing your own research is nicer than relying on a poorly-researched article. -
Re:This isn't new information, just misinformation
Bullcrap. USB2.0 = 480MB/s. I dare you to show me documentation otherwise, dumass.
Challenge Accepted
High Speed USB is 480Mb/s or 60 MB/s. -
Re:NothingCorrect.
Their claim is that USB 2.0 is a spec that supports three speeds. "Hi-Speed" is just one of the three that goes at 480 MB. Any USB 2.0 device will play on a USB 1.1 or USB 1.0 wire, but only at the slower supported speeds.
However, a full-speed (not hi-speed) device shouldn't be allowed to be labeled "USB 2.0 compliant" since it cannot use the whole USB 2.0 spec. That claim would be equivalent to saying a 300 baud modem is V_fast compliant just because a V_fast modem has to be able to slow down to talk to it.
Because of the inability of marketroids to be able to grasp these facts, USB is trying to get away from the 2.0 vs 1.1 naming game altogether. Packaging is supposed to say only "USB" or "Hi-Speed USB", and not label it with a version number.
Of course, then I find this crap on the USB packaging page referring to "Low or Full-speed Product Packaging Recommendations:"
Avoid using terminology such as USB 2.0 Full Speed, Full Speed USB or USB 2.0 which can be confusing for consumers whose expectation is that a USB 2.0 product is by definition high-speed.
Side or Back of Packaging Key Messages (Detailed Information)
1. Compatible with the USB 2.0 Specification
2. Works with USB and Hi-Speed USB systems, peripherals and cables.So manufacturers can claim a full-speed device is USB 2.0 "compatible." That's really, really shady. The correct answer is that USB 2.0 devices can claim compatibility with USB 1.1, not the other way around.
Yep, that's pretty dishonest labeling. And from a computer industry group! I'm amazed!
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They did NOT renames USB 1.1 to USB 2.0
The author must have been smoking something. I just drilled down a bit into USB home and I see no reference to renaming USB 1.1 to USB 2.0. They have renamed USB 1.1 to USB Full-Speed and USB 2.0 to USB Hi-Speed and use those new names consistantly throughout their web pages. Though the renaming was hardly necessary, it is unambiguous and isn't really any different than the periodic product renaming done in most industries for 'marketing reasons'.
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This is hilarious!I found this on their site: when you click the link for "Hi-Speed" it takes you to this URL: http://www.usb.org/developers/usb20
And this is even better: follow the link to the Hi-Speed FAQ where they answer questions like this:
1: What maximum speed was finally chosen for the USB 2.0 spec?
A: The USB 2.0 specification has a design data rate of 480 mega bits per second.Of course, if if this gives you a general misconception, you should head to the USB packaging page where you will be enlightened by this paragraph:
Inconsistent use of terminology in combination with the existing general misconception that USB 2.0 is synonymous with Hi-Speed USB and/or failure to display the Certified USB logo on qualified products creates confusion in the marketplace. The correct nomenclature for high-speed USB products is "Hi-Speed USB." The correct nomenclature for low or full-speed USB products is simply "USB." This should be taken into consideration for product naming.
So, now they are saying we have a misconception that USB 2.0 is Hi-Speed. But it's our misconception, not theirs.
Of course, Gareth Powell, the original author of the story, might have gotten his facts wrong or confused, and has simply started a flamefest with ignorance. USB 2.0 is merely a specification that encompasses ALL THREE SPEEDS. However, if a device is USB 2.0 compliant, it, too, had better support ALL THREE SPEEDS (and not just by dumbing down to the lowest speed supported.) But nowhere in his article does he say that a full-speed only connection is now being referred to as USB 2.0. He just says Toshiba is selling USB 1.1 laptops as USB 2.0 laptops, but does not say if they do or do not support Hi-Speed USB.
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This is hilarious!I found this on their site: when you click the link for "Hi-Speed" it takes you to this URL: http://www.usb.org/developers/usb20
And this is even better: follow the link to the Hi-Speed FAQ where they answer questions like this:
1: What maximum speed was finally chosen for the USB 2.0 spec?
A: The USB 2.0 specification has a design data rate of 480 mega bits per second.Of course, if if this gives you a general misconception, you should head to the USB packaging page where you will be enlightened by this paragraph:
Inconsistent use of terminology in combination with the existing general misconception that USB 2.0 is synonymous with Hi-Speed USB and/or failure to display the Certified USB logo on qualified products creates confusion in the marketplace. The correct nomenclature for high-speed USB products is "Hi-Speed USB." The correct nomenclature for low or full-speed USB products is simply "USB." This should be taken into consideration for product naming.
So, now they are saying we have a misconception that USB 2.0 is Hi-Speed. But it's our misconception, not theirs.
Of course, Gareth Powell, the original author of the story, might have gotten his facts wrong or confused, and has simply started a flamefest with ignorance. USB 2.0 is merely a specification that encompasses ALL THREE SPEEDS. However, if a device is USB 2.0 compliant, it, too, had better support ALL THREE SPEEDS (and not just by dumbing down to the lowest speed supported.) But nowhere in his article does he say that a full-speed only connection is now being referred to as USB 2.0. He just says Toshiba is selling USB 1.1 laptops as USB 2.0 laptops, but does not say if they do or do not support Hi-Speed USB.
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This is hilarious!I found this on their site: when you click the link for "Hi-Speed" it takes you to this URL: http://www.usb.org/developers/usb20
And this is even better: follow the link to the Hi-Speed FAQ where they answer questions like this:
1: What maximum speed was finally chosen for the USB 2.0 spec?
A: The USB 2.0 specification has a design data rate of 480 mega bits per second.Of course, if if this gives you a general misconception, you should head to the USB packaging page where you will be enlightened by this paragraph:
Inconsistent use of terminology in combination with the existing general misconception that USB 2.0 is synonymous with Hi-Speed USB and/or failure to display the Certified USB logo on qualified products creates confusion in the marketplace. The correct nomenclature for high-speed USB products is "Hi-Speed USB." The correct nomenclature for low or full-speed USB products is simply "USB." This should be taken into consideration for product naming.
So, now they are saying we have a misconception that USB 2.0 is Hi-Speed. But it's our misconception, not theirs.
Of course, Gareth Powell, the original author of the story, might have gotten his facts wrong or confused, and has simply started a flamefest with ignorance. USB 2.0 is merely a specification that encompasses ALL THREE SPEEDS. However, if a device is USB 2.0 compliant, it, too, had better support ALL THREE SPEEDS (and not just by dumbing down to the lowest speed supported.) But nowhere in his article does he say that a full-speed only connection is now being referred to as USB 2.0. He just says Toshiba is selling USB 1.1 laptops as USB 2.0 laptops, but does not say if they do or do not support Hi-Speed USB.
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Article is bunk or USB Forum site is wrongCalm down! Didn't anybody check the USB.org website to see if this is real?!?
Look here http://www.usb.org/developers/packaging/, and I quote:
"Low or Full-speed Product Packaging Recommendations:
"Products that operate at only low or full-speed can qualify to use only the Basic Version of the logo (i.e. without the special Hi-Speed identifier). The old USB logo is obsolete and should not be used. The USB-IF recommends vendors simply use "USB" as has always been done, on packaging and in marketing materials for low or full-speed USB products. Avoid using terminology such as USB 2.0 Full Speed, Full Speed USB or USB 2.0 which can be confusing for consumers whose expectation is that a USB 2.0 product is by definition high-speed."
In other words, - There are 3 speeds; low (1.5Mb/s), full (12Mb/s) and high (480Mb/s). - All 3 speeds can be described as "Compatible with the USB 2.0 Specification" - ONLY the high speed should be labels as "USB 2.0"
If they made the claimed change back in December and still haven't updated the web site, they are idiots twice! Otherwise, the article is blowing hot air.
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Picture tells the story
The two logos, side by side. Not that
bad if you know what to look for ... -
From usb.orgQ1: How fast is USB?
A1: High speed USB products have a design data rate of 480 Mb/s. Full speed USB devices signal at 12Mb/s, while low speed devices use a 1.5Mb/s subchannel.From the USB FAQ, seems they just dropped the 1.1 and 2 designation, there's no mention of them on their website. My guess is the mfg's are pulling the fast one, although the High speed/full speed naming convention should be clearer.
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Ask the Developers
Let's see what shakes out on USB's developer discussion board; presumably someone there should have an opinion...
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Welcome to Managementspeak101From the usb.org FAQ
Q1: How fast is USB?
A1: High speed USB products have a design data rate of 480 Mb/s. Full speed USB devices signal at 12Mb/s, while low speed devices use a 1.5Mb/s subchannel.
So full speed (which a sane person would think implies maximum speed) is slower than high speed. I think its about time that the USB forum got some new members.
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Re:Now I understand
See Question 2 from the FAQ.
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Re:Huh?
The article refers you to www.usb.org.
Going to the FAQ there, specifically here, and you see this:
Q1: How fast is USB?
A1: High speed USB products have a design data rate of 480 Mb/s. Full speed USB devices signal at 12Mb/s, while low speed devices use a 1.5Mb/s subchannel.
However, I can't find out anything where they say to refer to "USB 1.1" as "USB 2". It's chock-full of Hi-Speed/Full-Speed marketspeak, though. This is very confusing nomenclature. -
Uh
Here's some info on the USB Forum... there's more than just Intel and MS involved in these decisions.
~Berj -
Re:A wired standard would be more useful to me.
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Re:Someday maybe...
The USB standard includes specifications for various device classes. You can support all devices that properly follow their device class standards with a single driver. For printers you still have to have a printer-specific driver (or at least a driver specific to the document language your printer uses).
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Re:Counter points
"Why doesn't it use a MicroUSB Connector?"
Probably because there are already two different small USB implementations,
Two? I'm aware of one smaller-connector standard. There are two plug types just as there are for the full-sized connectors, the mini-A and mini-B, but the role of the device (host or target) makes it clear which one to use. The watch is a target so it could have a mini-A plug (for which there are supposed to be adapters to A) or a mini-B socket.
I wish these smaller connectors would get more traction because though the cameras we design all come with Mass Storage Class, some manufacturers still choose to use proprietary connectors. -
Re:Counter points
"Why doesn't it use a MicroUSB Connector?"
Probably because there are already two different small USB implementations,
Two? I'm aware of one smaller-connector standard. There are two plug types just as there are for the full-sized connectors, the mini-A and mini-B, but the role of the device (host or target) makes it clear which one to use. The watch is a target so it could have a mini-A plug (for which there are supposed to be adapters to A) or a mini-B socket.
I wish these smaller connectors would get more traction because though the cameras we design all come with Mass Storage Class, some manufacturers still choose to use proprietary connectors. -
Re:Card-based computer
There was an attempt by a number of PC manufacturers at defining an expansion cartridge format for the PC, similar to the laptop expansion bays, based on USB and FireWire, but (rumor has it) Intel killed it because they didn't want any non-Intel technology (i.e. FireWire).
Intel 'killed' it? Thanks for being so specific. There have been hundreds of similar proposals throughout the years, and they have all failed because there really isn't a demand for them.
Ah well, at least Intel can keep getting USB royalties... :-)
Take a look at usb.org and tell me how much the USB royalties are (hint- you don't pay any royalties). -
PDA with USB "on-the-go"I know this is off-topic, but does anyone know if there is a USB2.0 on the go enabled PDA on the market?
I would dearly love to get my Archos Jukebox USB drive running on the PDA, as it requires no external power from the USB port, it shouldn't drain batteries too much.
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Developer Info
More On The Go details can be found at the USB association's web site
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Re:Probably isn't going to work.Ethernet is also a differential signal - signal skew is simply not that big of a deal, especially at USB speeds. Light travels a long ways in one clock cycle.
Impedance also isn't a big deal. According to this, it's supposed to be 90 ohms, and the spec allows for 15% variation. Cat5 is about 100 ohms.
What is important is timing. According to this, the low-speed timing limitation is 18ns, or 300000000*.000000018 = 5.4 meters. Significantly under 30 feet.
Size of solder joints... sheesh.
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Re:Probably isn't going to work.Ethernet is also a differential signal - signal skew is simply not that big of a deal, especially at USB speeds. Light travels a long ways in one clock cycle.
Impedance also isn't a big deal. According to this, it's supposed to be 90 ohms, and the spec allows for 15% variation. Cat5 is about 100 ohms.
What is important is timing. According to this, the low-speed timing limitation is 18ns, or 300000000*.000000018 = 5.4 meters. Significantly under 30 feet.
Size of solder joints... sheesh.
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Electrical Limitations
From The USB FAQ
Q3: Why can't I use a cable longer than 3 or 5m?
A3: USB's electrical design doesn't allow it. When USB was designed, a decision was made to handle the propagation of electromagnetic fields on USB data lines in a way that limited the maximum length of a USB cable to something in the range of 4m. This method has a number of advantages and, since USB is intended for a desktop environment, the range limitations were deemed acceptable. If you're familiar with transmission line theory and want more detail on this topic, take a look at the USB signals section of the developers FAQ.
Essentially, the USB cable is a mismatched transmission line. As a result, the signal reflects off of the ends of the cable, resulting in a stair-step pattern whenever the voltage level on the line changes. As the cable gets longer, it takes more time for this stair-step pattern to settle to the final voltage. -
"For a low speed device the limit is 3 meters."
"For a low speed device the limit is 3 meters (9 feet 10 inches)."
From USB.ORG's USB Info: Frequently Asked Questions
In practice, manufacturer's technical support representatives often say that their devices will not work with a cable longer than 2 meters (6 feet), and they supply a cable of that length. In many office situations, a cable that short is useless. But they are right, a longer cable doesn't work, and a hub doesn't work.
Ethernet and FireWire are examples of properly designed computer communication interfaces. They are trouble free.
USB 1.0 is an example of a poorly designed and poorly implemented interface. USB often interferes with computer hibernation, to give another example. -
Re:What was a new USB architecture even needed?
Without looking at the specs to see, it's rather obvious that the hardware people just redesigned the interface all over again.
>>>>>>>>>
Well, here are the specs so you don't have to make stuff up:
USB 2.0
USB 1.0
The real difference is here:
OHCI (USB 1.0 host controller, this is the better one)
UHCI (USB 1.0 host controller, the sucky one)
EHCI (USB 2.0 host controller spec, has more smarts like OHCI) -
Re:What was a new USB architecture even needed?
Without looking at the specs to see, it's rather obvious that the hardware people just redesigned the interface all over again.
>>>>>>>>>
Well, here are the specs so you don't have to make stuff up:
USB 2.0
USB 1.0
The real difference is here:
OHCI (USB 1.0 host controller, this is the better one)
UHCI (USB 1.0 host controller, the sucky one)
EHCI (USB 2.0 host controller spec, has more smarts like OHCI) -
USB 2.0?
Perhaps they're using USB 2.0. If so, I still don't see why firewire wouldn't be a better choice.
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Re:Advantage?
5) USB 2.0 can't power the unit, while firewire can, so I never have to bring an AC adaptor *anywhere*.
Hard to take you seriously when you can't even get simple facts straight. USB has always provided power to peripherals. Check their web site if you don't believe me. -
the USB specifications...
can be found here for both USB v1 and v2
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Still camera - remote control?
Some digital still cameras have USB remote control (Minolta is one); this might be cheeper than using a webcam, depending on what equipment you have to hand. It should be easier on the batteries as the CCD/LCD display should power down after each photo.
The jPhoto Linux USB driver should do the trick, see www.linux-usb.org/devices.html, http://jphoto.sourceforge.net, or the tech. spec. pdf -
USB absolutely uses DMA
I don't know where you're getting your information, but all 3 common USB host controllers (UHCI, OHCI and EHCI) use bus mastering DMA to transfer the data from the device to main memory.
Go check the USB host controller specs for yourself. -
Re:USB interface.
Basic USB 1.x is 12 Mb/s I'm pretty sure, so it sizes up nicely. USB 2.x is more in the neighboorhood of hundreds of megabits (480 I think?). More tech info is at usb.org.
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ACPI rocks, but can cause severe instability.
First of all, ACPI was created to a) make computers that "boot" instantly by always being in sleep mode and b) end the IRQ conflicts so common with earlier versions of Windows and hardware. So yes, ACPI, when working right, simply rocks.
However, ACPI on certain motherboards, especially AMD motherboards, can cause severe system instability with Windows 2000 and Windows XP. (Please note that these OSes don't freeze/BSOD under normal circumstances, so if you're seeing this, you probably have a hardware issue which could be related to ACPI.)
The most common scenario I have seen is this:
-- Someone decently technically savvy builds his/her own PC with an AMD chip;
-- Said person installs Windows XP;
-- Said person wonders why IRQs are all set to 9;
-- Said person goes and manually messes with IRQ settings, thus wreaking havoc on the poor commputer that functioned perfectly before.
It can also go the other way:
-- Said person installs Windows XP with AMD chip;
-- Said person experiences weird freezes;
-- Said person's computer works fine with Windows 98 because Win98 doesn't have full ACPI support, so person is left wondering why everyone says that Windows 2000 and Windows XP are so stable since that person's computer crashes constantly.
To turn off ACPI, reinstall Windows and set your computer type to "Standard PC." Here is an excellent guide on how to set your PC to a Standard PC. As mentioned in the guide, this gives you the added benefit of increased framerates in Quake 3. However, you have to manually turn your computer off, and it might not go into powersave mode properly. Here is another comment regarding ACPI.
So, to summarize:
-- If you're having problems with Windows 2000/XP freezing, try this fix. Freezes are indicative of a hardware issue. Your computer should be stable with these OSes (except for application crashes, which happen with every OS.) My current uptime with Windows 2000 is 27 days; I have seen over 100 days uptime. If you're not seeing this type of stability with 2000/XP, it's time to do some hardware diagnostics.
-- If you're not having problems, leave well enough alone and leave ACPI turned on.
-- Do NOT mess with your IRQs on an ACPI computer! By messing with IRQs manually, you're asking for weird system problems. Leave them all on 9 -- it won't hurt the computer.
-- Due to the problems mentioned above, I personally will not buy AMD chips and motherboards. I have yet to see ACPI problems crop up on an Intel motherboard. It's unfortunate, because I like AMD and like to encourage competition, but their chips and motherboards have strange issues that have yet to be resolved.
I hope this helps all of you who are having problems with Windows XP or 2000. -
Re:Well, if you think about it...
If Microsoft had wanted this, they could have just come up with a proprietary interface protocol with a really weird connector, both of which would be patented.
That's true, obviously it's been done before. The thing is, USB is extremely cheap (chipsets are only a couple $$, and cables aren't bad either), plus a lot of people know it since it's a pretty open standard, so you don't have to train people to use it. I mean, we're talking R&D, manufacturing, etc. lots of money here, not just drivers. Instead, they (predictably) choose to take an open-looking standard and twist it so nobody but them can play. How is this any different than what they've been up to their entire (corporate) life?
if you are a big company and you want to prevent competitors from manufacturing peripherals for your product, is there any law that would allow you do to so?
AFAIK, you can patent the interface. That's about it (copyright doesn't apply, and you can't call it a trade secret because - *doh* - millions of people have it.)
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Have you crashed Windows XP with a simple printf recently? Try it! -
Re:So?If Japan wants to sell controlers, they'll make them with the appropriate "US" USB settings.
USB vendor/product ID has nothing at all to do with "US" USB settings, in fact the only country-specific part of the USB spec is the String (descriptors) which have a lang id.
If the X-Box is discriminating based on USB IDs, it is locking out certain Vendors or certain Vendor's products. Most likely they are locking out certain vendors, as the product ID is really up to the Vendor; the Vendor ID is assigned by the USB-IF.
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Re:So?If Japan wants to sell controlers, they'll make them with the appropriate "US" USB settings.
USB vendor/product ID has nothing at all to do with "US" USB settings, in fact the only country-specific part of the USB spec is the String (descriptors) which have a lang id.
If the X-Box is discriminating based on USB IDs, it is locking out certain Vendors or certain Vendor's products. Most likely they are locking out certain vendors, as the product ID is really up to the Vendor; the Vendor ID is assigned by the USB-IF.
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Jobs knows that middle America runs the showbut that doesn't mean he wants to sell commodity products. Because BMW doesn't target 7-Eleven employees doesn't mean that their executives aren't aware of American automobile buying habits. It means that they've chosen to target a different audience.
Apple, like any large corporation, has a culture of its own. The culture at Apple favors certain things. It places a value on aesthetics and on how people interact with their computers. It places a value on taking risks in order to push new technologies (some of which Apple invented, like Firewire and others, like USB that it didn't). It places a higher value on originality and elegance than on following established norms.
A company with such a culture will never rule the world. It will never defeat Microsoft in the marketplace. It will never unseat Dell. But it doesn't have to. In order to grow and prosper, Apple just has to keep its customer base happy. Its customer base is not Ma and Pa Gateway.
For better or for worse, the people who like Apple products tend to actually enjoy using their computers. They don't usually care about whether they can play any one of 10,000 available PC games. They simply want a computer that allows them to accomplish things and to have fun while doing those things.
As long as Apple can keep providing products that innovate in favor of the user, they'll do just fine, and the rest of the industry will continue to use them as an R & D lab.
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Re:Still USB
If thats what you want, check the USB On the go extention to USB2.
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Re:USB or 1394
USB.org's FAQ says USB is 12Mbps (v2 is 480Mbps), and FC-AL is 3.2Gbps. Even commodity ATA/133 gives 1064Mbps. USB can't replace disk interfaces. FireWire can. (As can FC-AL, but FC-AL is as commodity as Space Stations).
Firewire's easy to use too. Plug and pray... -
USB 2 is royalty-free; FireWire is RAND
No, it's different. What sucks about USB is that it does everything that IEEE 1394 does, but a little worse.
And the cost per unit of USB hardware is much cheaper than that of 1394 hardware. The asymptotic law of hardware cost states that if you reduce the cost of one component or set of components that contributes say 3/4 of the cost of a device, you can't reduce the total cost lower than 1/4 of the original cost. USB and USB 2 are both licensed on a royalty-free relevant-patent-swap basis; 1394 requires payment of a 25c per device royalty. After three layers of markup (manufacturer, distributor, and dealer), this royalty can become significant.
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Re:USB may be slower but isn't all that slow
[Read the whole thing before you mod me Offtopic.]
Burning CDs, just like pretty much everything else, requires overhead. The pipe might be technically big enough to move that ammount of data but you still have to consider that error checking, device I/O, and other things have bandwidth needs as well. Similarly, your new ATA100 hard drive will never be able to move files at peak speed because of the overhead related to it.
It doesn't "suck", it's just the way it is. USB was not invented as a means specifically for CD-RWs. Notice that the U stands for Universal. Manufacturers just realized that there may be some people that would be willing to trade speed for USB's ease of use. Saying it sucks is like bitching that you can't burn at 24X over COM1. A comparative list of speeds can be found here if you're interested.
Back on topic: This is where the iPod has everthing else out there beat hands down. Even this new Treo has some nice features but it's still USB. But does it really matter? Yes, when you first load it it'll be a pain in the arse, but after you've cleared that hurdle I don't believe you'll be sitting for hours waiting to update it. A CD with ~12 songs encoded at 128k takes up ~40M. USB tops out at 1.5MB/s. Including the afformentioned overhead, you're still only looking at 1 minute per CD. Why is it we all act like we're so important that we can't wait that long?
Agreed, it is sexy that the iPod can move files like lightning, but how long do you think it will be untill someone wises up and makes a firewire MP3 player for PCs? -
Re:Why no USB then?
Nah, I'm pretty sure I got them right... I'll explain my math:
USB is 12 Mbit/sec. I guessed that since it's polled, that we wouldn't get peak efficiency and that maybe only 8 Mbit/sec was realizable. I'm also assuming the MP3 being transfered is encoded at 128kbit/sec. Thus, the transfer rate 'x' factor is 8192/128 = 64x. Transfering an MP3 file effectively increases the 'x' factor - to get the same number of seconds recorded on an uncompressed CD requires more data, which requires more time.
Now, the point's moot if you're burning CDs of MP3s, but even for normal CDs I would still find 64x to be worthwhile.