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USB2 Specs Are In
PooF writes "USB 2.0 has been announced. It seems sweet, its faster than firewire at 480 Mb/s.
An article from pc.ign.com on USB 2.0. Oh yea these are only the specs they hope to achieve no word on progress in implementing them."
This was covered in an earlier slashdot thread this summer. Faster USB is great. 12 MBits/sec is fast by serial port standards, but not fast enough for some of the things people want to use USB for (low-end video transfer, external mass storage, Ethernet, etc.). Despite that, there's a great mass market for Firewire, too. Here's why:
1: USB already has low-speed, misbehaved, "legacy" devices that need to be backwards compatible with the new spec. Firewire's legacy peripherals operate at 200 Mbits/sec. 'nuff said.
2: USB requires processor arbitration to run the bus. Firewire doesn't.
3: USB's design is specifically as a low-cost interface for PC peripherals. The hub-based design is a byproduct of this. Firewire is designed as a more general-purpose, device/device interface. Firewire can nicely connect consumer products to one another, no PC required.
However, USB has a higher "theoretical" maximum number of devices supported per controller, 127 (in USB 1.1), versus Firewire's 64. In practice, 64 Firewire devices is do-able, if silly. More than 4-5 USB devices (with a powered external hub) is pushing the limits. The only place where USB reaches the upper limits is at USB technology bake-offs.
I love USB (heck, it's in all my PC's and both my home Macs), and it's a great cross-platform standard for computer-oriented low-end to midrange peripherals. Firewire is better for high-end devices (prepress scanners, hard drives, video equipment, etc.), but it's a general-purpose interface, and that's why it will ultimately do well. The two interfaces are not, by any stretch of the imagination, mutually exclusive. Anybody who thinks that you can only use one either needs to buy a Mac to prove otherwise or board the cluetrain.
- -Josh Turiel
-- Josh Turiel
"2. Do not eat iPod Shuffle."
OK, I'm actually at the USB 2.0 Devcon right now, and have read the 2.0 proposed spec, so I'll take a stab at refuting these comments:
1.The usb.org article only claims "120-240Mbps". It's not clear where the ign.com article came up with 480Mbps.
The speed is 480Mbs. That is what the spec says.
2.Even if USB2 runs at 480Mbps, the Firewire folks aren't exactly standing still. Any raw bandwidth advantage of USB2 is sure to be short-lived at best.
Firewire and USB have too many things that are not in common, they really are not competitors. USB is aimed to be a PC centric bus. There has to be only one host, and a whole lot of clients. Firewire can be host to host. Firewire is more intrenched in the consumer electronic market, while USB is sticking to the PC (for now).
3.There's lots of blather in the USB2 announcement about supporting video cameras etc. but IIRC USB doesn't support the isochronous transfers which are usually considered necessary to serve those markets. Did I miss something?
You missed something. USB has always supported isochronous transfers. Look at the USB speakers from Philips for an example of a shipping product that uses this. Isochronous is still there for 2.0.
4.Another useful Firewire feature that USB doesn't seem to have is providing power through the same connector used for communications. Again, I may have missed it.
USB has ALWAYS supported power on the connector. How else does some of the devices work? 2.0 does not change this. It's still 5V at 100mA-500mA depending on what you need and ask for. If you need more power, take a look at the Plus Power Connector that IBM supports for USB. It can provide 12V or 24V at 3A. That's about all the current that anyone needs.
5.I don't remember how many devices USB supports, but I suspect it's less than Firewire.
USB supports 127 devices per host controller. You can plug in more than one host controller in your PC at a time. The record (I think) for most devices plugged in and working at once is around 144.
6.I know that USB-based host-to-host networking exists, but it's not clear to me whether it's really as well suited to that task as Firewire. In particular, I wonder how much asymmetry between hosts and devices (a la initiators and targets in SCSI) is built into the protocol, and how round-trip latency compares to other technologies.
As I said above, USB is a host-client bus. You can make (and buy) a device that does networking over USB from one computer to another, but this is just two client devices talking together in a box. Firewire can do true host to host on the bus itself. The USB protocol is a star topology with the PC host controller at the top. I can look up the round trip latency stuff somewhere, but it is built into the protocol, and the host and hub controllers seem to handle it well.
7.Similarly, I'd like seeing a comparison of how automagically reconfiguration happens when devices are added or removed using each technology.
I don't really know how Firewire does this at all, but USB handles this wonderfully. There is a description of how the protocol handles all of this in the spec (at www.usb.org).
In summary, USB 2.0 looks like it handles a lot of the speed issues that some people had with 1.1. It provides backward compatibility with all 1.1 and 1.0 devices and enables things like speakers and video cameras to run better.
Like it or not, USB looks to be here for a while. A lot of computers are coming out without a lot of different connectors, and USB is replacing them.
Ob Linux: USB is working on Linux in the 2.3.x series of kernels (it's also supported a little in the 2.2.x series, but not for many devices.) More information is at www.linux-usb.org
I believe that I read somewhere (MacWEEK? The Register?) that USB 2.0, which isn't even being developed beyond a spec, was a move by Intel to try to squash FireWire for some reason. My memory fails me as to where I read that article. It was speculative, not stating it as fact, but it said basically what the comment said: not really being developed, just announced. What sort of practice does this remind you of? (Answer: MS in the 1980s and early 90s.)
We have enough trouble getting USB 1.16 to work under Linux.. don't need to mess with 2.0.
-- haaz.
I think not. USB 2.0 may be faster in terms of throughput than Firewire, but not on CPU utilization. USB sucks up more processor, and thereby slowing your entire machine down. This is another example of Chipzilla driving a "need" for faster processors. Remember about a year ago when DVD technology came to the PC arena. Some video card companies came out with hardware DVD decoding solutions. Intel made the push that their Pentium II processors could easily handle software decoding of DVD, and therefore the hardware DVD solutions were not needed. I'm all for the fastest processor, but not when it's need to mask performance bottlenecks in other areas. Who wants to do one thing on their PC? Why do we even try to multitask? And I guess the fact that Firewire was invented by Apple has nothing to do with Intel pushing their new "faster" solution.
Actually, this is specsmanship. Where IEEE1394 does its arbitration, framing, etc. at a minimum of 100 Mb/s and usually at 400 Mb/s, USB of any flavor does its polling (notice, it is *not* a peer interconnect) and framing at no more than 12 Mb/s (assuming that there are no low-speed 1.5 Mb/s devices in the path).
Each packet in USB2 starts out with the same preamble (12Mb/s) and ends with the same postamble (12Mb/s); the new twist is that there may be a tone burst in the middle of 480 Mb/s or whatever. Unless you ship really huge packets (which aren't allowed by the protocol anyway) the average transfer rate is a lot lower than 408 Mb/s.
Lacking <sarcasm> tags,
I think you mean as Apple was trying with the name "firewire". Apple gave up on that quite a while ago, realising it wasn't making them any friends or winning acceptance for FW. It was right around that time that Intel initially announced USB2.0. Months and months ago this was. (Which reminds me -- this ain't exactly news, Roblimo...)
This has been said so many times that I risk losing karma here for being redundant...
USB and Firewire were never intended for the same purpose! USB was intended for low-bandwidth stuff (mice, keyboards, printers, speakers). FW is aimed at higher bandwidth stuff. Most typically, your average home computer user would probably prefer a FW hard drive. DV and even networking are also within FW's desmesne.
Look at the G3 and G4 machines from Apple. USB and FW co-exist. Why on earth would you need your hard drive's bus and your mouse's bus to be co-compatible?? Sounds to me like you're saying that SCSI was a bad idea because you couldn't run your mouse through it. If you buy a SCSI PCI card, do you need to buy a new keyboard?
As for your implied price comparisons between USB hard-drives and FW hard-drives... you get what you pay for. I don't know for sure, but I strongly suspect that USB drives are cheaper because they don't need to be as fast. It's like comparing SCSI drives with IDE drives. SCSI may be technically superior (and faster), but IDE is cheaper. You may be kicking yourself later when the latest & greatest thing needs a hard-drive connection faster than USB can provide you...
Um, you're talking about the iMac, right? They dropped the (archaic) floppy, used USB for *everything*, and had networking installed in the box. The newer iMacs also have DVD, firewire/iLink, wireless networking options, and advanced power saving features until now only found in notebooks. Welcome to the next level
-AS
-AS
*Pikachu*
of course, i can't use my current USB hubs, my USB cables, or USB pass thrus (essentially, built in hubs) on any of my devices...
how exactly do you cram 480 mbps thru ports that can only support 12? Your monitor with 4 USB ports can't support USB 2.0. Your hub can't support USB 2.0. You have to buy all new hardware - including USB cables - to use USB 2.0. Your USB 1.0 devs will all have to be at the ends of your USB device tree.... If you plugged a USB 2.0 HD into your USB 1.0 hub - it will run at USB 1.0 speeds.
USB 2.0 is only to sell more USB 2.0 chipsets and to require you to keep buying faster and faster Intel CPUs.
get a grip. Get Firewire.
___
"I know kung-fu."
guns kill people like spoons make Rosie O'Donnell fat.
"because they are not *true* Firewire drives. They are aftermarket modifications to IDE or SCSI hard drives."
This last shows a profound mis-understanding of the difference between IDE and SCSI drives. The Mechanisms are THE EXACT SAME! The only differnces are that the best of any run of a mechinism, and the newest technologies in drive production, go into the SCSI channel, where they are paired up with a SCSI controller card (SCSI bus talks to card, card talks to mechanism..).
All you have to do is look at a SCSI drive, and a IDE drive from the same vendor and look at them. The green board on the SCSI drive is more complicated (assuming that you are looking at older drives.. newer ones have more concetrated in the ASICS). In principal you caould take a SCSI drive rip off the controller card, and put on a IDE card. The same is genericly true for FireWire.
Now there is one differnce will all the FireWire drives that I have had to play with, they are all designed to be very rugged, and portable. That means that they are based on the same mechanisms used for laptop drives. This means they have sacraficed some speed, and a lot of cost, in order to be more rugged, and to be smaller (lower power too...). You can shake that VST drives all you want, while they are reading data, and they still keep rigth no going.. try that with a desktop drive!
I've heard tell about some sort of IO standard that Intel's been pushing of late that supposedly 'replaces all current bus technology'. Anybody know more about this?
I personally am looking forward to hearing more about Jini, which is Sun's initiative to do to hardware what Java is doing to software.
Basically, they move the device abstraction out of the OS driver and into the device itself. So you basically plug a Jini-enabled device into the network, and it immediately registers itself and makes its services available to other devices on the network.
No OS-specific drivers, no kludges/workarounds. Things just "work".
http:/www.sun.com/jini/
With any luck, someone more clueful can fill in the blanks above.
Overall, Firewire still looks like a generally superior technology in its niche, while the USB folks should have been content with their own separate niche (lower-bandwidth peripherals such as keyboards, mice, joysticks and modems that don't need advanced features such as isochronous transfers).
BTW, I don't actually use Firewire and have no interest beyond the aesthetic in promoting it. My employer is thoroughly committed to (ick) FC.
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As an employee of Intel I have seen first hand the desire to kill Firewire. Part of it is the licensing fee the other is to make the processor be so damn important that they can sell more and more. Don't get me wrong, Intel is all for new technologies... but only if they have their fingers in the pie as well.
Well, if this is intended to kill Firewire then that would be ironic since it's basicly Apple fault that USB has some success anyway.. Untill the iMac USB was not really taking off.
Infact, AFAIK, in the PC landscape there is still a very low demand for USB perif's relative to serial and scsi devices.
The main question is if Motherboard makers in the PC arena will continue to exclude Firewire ports for PCs (likly since intel mostly has controll over the chip sets), when media machines are alwredy adopting it (digital video now, and music instruments within the next year).
I think the battle is still open, USB 2 does have a chance to overthrow firewire, but to do this intel has to move fast. And intel has to convice the periferal makers to adopt USB2 instead of firewire - which might be dificult since those makers were burned in the past with USB slow adoption rate.
which ever standard actualy wins is hard to know, but It's going to be interesting watching the war. get your beer and nacho's ready..
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MacKiDo (reprinting a Mac Weekly Journal article) had an article weighing USB vs. Firewire last March that lists the advantages of 1394 over USB 2.0.
Current IEEE 1394 developer and maintainer, at your service :-)
It works with asynchronous transfers. I'm currently working on updating the userspace raw1394/libraw interface. When I'm done I'll try to get it into Linux 2.3 again (even though it's in feature freeze, but this subsystem does not affect any other code in the kernel).
Isochronous transmissions are not yet supported and I know that this is important for the people who want to get pictures from their cameras. At least isochronous receiving should not be too hard to implement, that is around next on my todo list.
As for the supported hardware: AIC5800 (out of production AFAIK), PCILynx (hard to come by, obsolete), OHCI (the standard of the future, implemented in hardware by various chip manufacturers). A Sony chip also exists (e.g. in the Vaio laptops), but is not yet supported. My OHCI card (donated by ADS Technologies) for some reason doesn't work, but I'm concentrating on PCILynx for the time being.
Hm, Intel is still trying. However, Texas Instruments (major implementor of 1394 chips) expects them to give up soon (end of this or next year) or be given up by hardware vendors. The move is to include 1394 on motherboards soon, USB 2.0 is vaporware.
As for the speeds: 1394 does 400Mbps now (you can buy slower chips, but they are more expensive and harder to come by because they are only still in production for US military use). USB 2.0 is said to have little more than 400Mbps sometime in the future. Given the technology it is also in doubt if they ever reach that.
Future 1394 (IEEE 1394.b) is in draft and partly implemented in experimental hardware. 1394.b specifies 100Mbps on 50 meter UTP5 cables, 3200Mbps on 100 meter optical cables or 4.5 meter conventional cables. It is interoperable with 1394.a, whereas USB 2.0 will be incompatible with USB 1 (AFAIK, I'm not sure). By the time 1394.b is in silicon with 3.2Gbps, USB 2.0 will probably just have reached 480 Mbps...
One killer application for 1394 are the video cameras of which more and more come with a 1394 port (aka i.Link on Sony devices). 1394 is very nice for that. You can plug your camera into a 1394 VCR and copy your material over or display them on a 1394 digital TV (in theory, I don't think there are many 1394 VCRs and TVs out there already). This is something USB just cannot do. Yes, it could in theory, but USB is PC centric. It requires a PC and moves all data through your PC. No possibility just to connect a digital VCR to a digital TV. You'd need a PC and a program running on the PC to copy the data. There is simply NO WAY that USB 2.0 would make it into video cameras or similar devices.
So 1394 would have to be supported in a multimedia environment anyway. When you have 1394 why bother with USB 2.0, which would do the same as 1394 only not as good?
USB 1 sure has its place in PC environments (it would be quite overkill to connect your mouse or keyboard through 1394). But trying to push some variant of USB as a competitor for 1394 is just silly, it's just that Intel wants the market share.
Also, for the FireWire "tax" by Apple, yes, some sort of it is still in effect. Chip vendors have to pay $.50 license fee per 1394 device (device, not port) to Apple, but that 50 cents won't bring it down.
And 1394 doesn't need those silly hubs.
There is the GNU/Lunix IEEE 1394 Subsystem, but does anyone know how well this works/had experience with using it or knows if it will be included in the kernel sometime?
The USB 2.0 specs are indeed respectable. Think of all the irq's you wil save. But it won't eclipse firewire anytime soon.
Right now 400 Mbps is not a bottle neck for most consumer end hard drive setups. Firewire and Sony's iLink (both IEE1394) are being pushed in the DV realm, where this fat a pipe is really needed.
On an earlier post, someone speculated that Firewire supports more devices than USB. It does not. The USB 1.0 supports up to 128 devices (which, ironically, was proven true by Apple's employee's during in a bier-garten, not by Intel employees), whereas Firewire supports 63 in it's current incarnation. But if USB 2.0 does support it's 480 Mbps claimed speed, one doubts that it will be able to support 128 devices.
There are Firewire port prototypes at 800 Mbps (this is due out next year), and the 1600 Mbps versions are in the works. In any case, more development has been done on 1600 Mbps Firewire than USB 2.0.
Everything seems to point to Intel launching a FUD war against IEEE 1394 technology. I suppose announcing a product months ahead(or perhaps years in this case) is typical of any large corporation, but there are other indices. 480Mbps is a minimal improvement over Firewire 1.0's 400 Mbps, but just enough to convince consumers and vendors. And, as speculated by SuperScan, USB 2.0, like USB will utilize CPU power to get by, whereas Firewire delegates this task to the Firewire controller.
Firewire is a part of the "PC2000" standard that was proposed by Intel and Microsoft. Maybe Intel wants to revise that proposal.
Recall that Firewire is not solely an Apple technology. Sony is hard core on IEEE 1394 (PSX2 will have Firewire ports), as well as others. If intel wants to dominate all bands of the peripheral device spectrum with USB + USB 2.0, they're going to meet some stiff resistance.
This kind of move just shows how intent Intel is on being the MS of the hardware world. By selling a CPU reliant standard, they get to dip in your wallet twice.
Btw, does anyone know if it's true that Apple cancelled it's 1 dollar licensing charge for Firewire ports? (By (un)popular demand?)