Firewire to USB 2.0 adapter?

Cursor

macrumors 6502
Original poster
Jul 17, 2002
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Thanks in advance for any help given. I have a Rev. A iMac G4 running Panther. A family member gave me a new external dual layer DVD burner for my birthday. My dilemma is that it uses USB 2.0 to connect to the computer. My iMac only has firewire and USB 1.0 (which is much too slow to burn DL DVDs). Does anybody know if there are any USB 2.0 adapters that would work with my firewire ports? Or is there another way to hook up this external burner? Any help would be appreciated. Thanks.
 

ftaok

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Jan 23, 2002
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Cursor said:
Thanks in advance for any help given. I have a Rev. A iMac G4 running Panther. A family member gave me a new external dual layer DVD burner for my birthday. My dilemma is that it uses USB 2.0 to connect to the computer. My iMac only has firewire and USB 1.0 (which is much too slow to burn DL DVDs). Does anybody know if there are any USB 2.0 adapters that would work with my firewire ports? Or is there another way to hook up this external burner? Any help would be appreciated. Thanks.
Nope. You're better off returning it for a Firewire model.

The G4 iMac doesn't have any expandability (i.e. PCI slots, PC Card slot), so you can't get an aftermarket USB2 card.

This is the same issue with people wanting the new iPods and nanos, but not having USB2.
 

Cursor

macrumors 6502
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Jul 17, 2002
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That's what I was thinking, too. I just wanted to make sure there wasn't any external hardware option (like somekind of bridge) before I went to the trouble of returning it.
 

grapes911

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Cursor said:
That's what I was thinking, too. I just wanted to make sure there wasn't any external hardware option (like somekind of bridge)
The bridge would require a processor to do conversions, memory to work with, probably a hard drive for a buffer. Basically, you'd need another computer. Probably best to just return it.
 

topgunn

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Nov 5, 2004
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How about something like this? For $90, it ain't cheap and it is designed for DV camcorders to be used without a firewire connection but the idea is still the same.

The problem is that demand is not strong for this sort of item. The market would consist of Mac users owning 3-5 year old computers that have firewire 400 but USB 1.1. That is roughly 40% of the Mac market which is 5% or so of the total market, so not much.
 

cube

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May 10, 2004
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grapes911 said:
The bridge would require a processor to do conversions, memory to work with, probably a hard drive for a buffer. Basically, you'd need another computer. Probably best to just return it.
If USB2 can be throttled to 400 Mbps there's no need for such crazy specs.
 

Cursor

macrumors 6502
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Jul 17, 2002
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Looks like I'll be returning it. Thanks a lot for all the advice.
 

cube

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grapes911 said:
But the user doesn't have USB 2.0, only USB 1.1 and FW. That is the whole point of this thread.
The bridge should throttle the USB2, that's what we are talking about.
 

balamw

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grapes911 said:
I'm sorry, I really don't know what you are talking about.
I believe what he's saying is that if you can be sure that the USB data rate will be kept below 400 MBps (throttled back from the 480 Mbps burst rate possible in USB2) that the circuitry could be made simpler/cheaper.

I disagree, since there will generally be some overhead required to translate between the two protocols. The data packets (length header format, etc...) for the two protocols are most likely different, so it's not just a simple 1:1 bridge

The evidence I have for that is that the reverse devices that allow you to connect nominally lower bandwidth firewire devices in to USB2 are generally not inexpensive like the one that was mentioned above.

It should also be noted that the Pixela device mentioned above is not presented as a general USB to Firewire solution as it seems to only support firewire DV camcorders.

B
 

grapes911

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balamw said:
I believe what he's saying is that if you can be sure that the USB data rate will be kept below 400 MBps (throttled back from the 480 Mbps burst rate possible in USB2) that the circuitry could be made simpler/cheaper.
If that is what he is saying, the I'm pretty sure it won't work. USB 2.0 runs at 480 or 11. There is nothing in between.

I disagree, since there will generally be some overhead required to translate between the two protocols. The data packets (length header format, etc...) for the two protocols are most likely different, so it's not just a simple 1:1 bridge
Very true. Conversion must be done.
 

Cursor

macrumors 6502
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Laser47 said:
Cant you remove the cd burner from the enclosure and put it in your imac?
I guess I could. But I'm not that technical with taking apart the sunflower iMacs. How hard is it to do? Would the computer be able to recognize the drive?
 

grapes911

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Laser47 said:
Cant you remove the cd burner from the enclosure and put it in your imac?
That would be a very expensive internal drive. It would be much cheaper to return it get an actual internal one. Not to mention it probably would void the warranty.
 

cube

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balamw said:
I disagree, since there will generally be some overhead required to translate between the two protocols. The data packets (length header format, etc...) for the two protocols are most likely different, so it's not just a simple 1:1 bridge
There's no problem making little SCSI/FireWire converters, why should there be one making USB/FireWire [chips]?
 

cube

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grapes911 said:
If that is what he is saying, the I'm pretty sure it won't work. USB 2.0 runs at 480 or 11. There is nothing in between.
It doesn't mean the devices can continously send at 480. This happens when you have more than one device trying to communicate at the same time, so in the same way one device could be throttled by the converter.
 

grapes911

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cube said:
It doesn't mean the devices can continously send at 480. This happens when you have more than one device trying to communicate at the same time, so in the same way one device could be throttled by the converter.
I'm pretty sure that it does mean that all packets are sent at 480. When there are multiple devices, they just take turns sending packets. Individual packets do not slow down.
 

Makosuke

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Aug 15, 2001
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topgunn said:
How about something like this? For $90, it ain't cheap and it is designed for DV camcorders to be used without a firewire connection but the idea is still the same.
Worth noting that "This" seems to be a very specific piece of hardware for converting a DV stream to some sort of USB2 stream; it's not just a data converter, as evidenced by the fact you have to order an NTSC or PAL version, depending on the type of video you're using.

And although I don't clearly understand the specifics of the various busses, I *think* the version that FW-USB2 converters don't exist is because the busses have fundamentally different ways of handling negotiation and data transfer. It's not so much a matter of amount of information, as the protocol. The reason FW-SCSI converters can work (actually, SCSI-USB1, too--they used to make those right after the first USB-only iMacs came out), even though the technologies are more "different", is because of the relative simplicity of the older SCSI bus formats--there's no issues with negotiation, variable speed, etc on it. FW may also have been specifically designed to include some of SCSI's features, but I'm not sure about that.

The other possibility is that it's just not much of a market; while there are some people with USB2 ports but no FW who might be interested in getting DV into their computer, almost nobody till now has USB2 peripherals but only a FW port, since USB is more common on Wintel boxes.

Maybe the USB2-only iPods will create enough of a market of older Macs that someone will produce a specialty product if it's technically feasable, though.
 

balamw

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Makosuke said:
FW may also have been specifically designed to include some of SCSI's features, but I'm not sure about that.
I think you're right about the inherent similarities between FireWire and SCSI. http://en.wikipedia.org/wiki/FireWire.

I've always thought that was a fair comparison.

FireWire :: SCSI (High performance comes with low CPU load, daisychainable, $$$)
USB :: ATAPI (performance comes with moderate CPU load, limited device connections, $)

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