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Old May 17, 2004, 12:16 PM   #11
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Hi,

USB2 Card Readers Speed is limited by Flash Card Speed.

Please, read my article below:

Recently I tested my new 6 in 1 USB2 Card Reader from SanDisk and found one interesting thing I missed before the purchase.

My settings for the test:

SanDisk SmartMedia Card 128 MB.
Pentium II - 450MHz.
OLYMPUS USB-1 Card Reader.
SanDisk USB-2 Card Reader.

The information for the reference I received from SanDisk:

> > SmartMedia card speed:
> > Read: 3.5MB/sec
> > Write: 500KB-1MB/sec (variable)
> > USB 1.1 ports have a shared bandwidth of 1.5 MB/sec.
> > USB 2.2 ports have a shared bandwidth of 60 MB/sec.

My thoughts and the results:

USB 1.1 port is limited by 1.5MB/sec bandwidth, but Read operation for SmartMedia card can be performed at 3.5MB/sec. The bottleneck here is a USB 1.1 port. By using USB 2.0 card we are shifting our bottleneck to SmartMedia card itself, and can perform Read operation with the max SmartMedia card speed 3.5MB/sec. It is 3.5/1.5 = 2.33 times faster.

==============================================
> OLYMPUS Card Reader on original USB-1 port:
>
> Read = 2.30 / Write = 4.38;
> ==============================================
> SanDisk 6 in 1 Card Reader plugged into new PCI based USB-2 port:
>
> Read = 0.59 / Write = 4.23;
> ==============================================

The read operation from USB 1.1 to USB 2.0 improved by 2.30/0.59 = 2.3 times.

Look like 2.3x is the max improvement we can get for the SmartMedia card by changing USB 1.1 to USB 2.0 (for Read operation).

For the write operation the bottleneck is SmartMedia card itself for both USB 1.1 and USB 2.0.

Look like we should not expect any improvement for the Write operation by switching from USB 1.1 to USB 2.0.

My conclusion:

USB-2 interface is 40 times faster, than USB-1, but do not expect such improvement by switching from USB-1 based Card Reader to USB-2 based Card Reader. The limitation is Flash Card itself.

The fastest Flash Card on the market has up to 7MB/sec transfer rate. It is far from USB-2 60MB/sec!!!


Thank you,

Andrei.
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Old Jun 4, 2004, 3:31 PM   #12
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I recently bought a new camera (Minolta Dimage S414) and am trying to decide between getting a seperate card reader or using the camera's USB cable. All speed issues aside, I was more concerned with wear and tear.

Is it more likely to wear out the USB port on the camera by plugging and unplugging the cable repeatedly, or wear out the CF card slot by removing / installing the memory card over and over?

6-in-1 USB2 readers are cheap, at least on eBay, so that really isn't the issue either. Just curious which route would be most likely to cause problems down the road.



While I have a post going, would it be worth the extra money to get the high speed CF card for this camera? There was a $30 increase in price from a standard 256M and the high speed 256M card. I am sure 256M will be plenty, but that $30 will take care of a charger and a couple sets of NiMH batteries...
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Old Jun 7, 2004, 11:38 AM   #13
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Any thoughts on the "wear and tear" issue?
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Old Jun 7, 2004, 8:23 PM   #14
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If you wear out the USB conncection on the camera, you can always get a card reader. If you trash the connections to the memory within the camera, you have a dead camera.

Neither of those is likely to happen if you are carefull.
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Old Jun 22, 2004, 8:28 AM   #15
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Just a warning to our friends on this forum. I recently purchased a Dazzle 10 and 1 card reader because it is one of the few that will read both Xd Picture cards and microdrives. However I discovered that when using their card reader to upload avi movie files to my PC, the card reader currupted all of the files (the files uploaded normally when using the camera's USB connection). When requesting assistance from Dazzle, they just tried to blame the drive and refused to help. By the way, I have tested several other much cheaper card readers that my friends use with good results.
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Old Jun 22, 2004, 9:35 AM   #16
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Quote:
==============================================
> OLYMPUS Card Reader on original USB-1 port:
>
> Read = 2.30 / Write = 4.38;
> ==============================================
> SanDisk 6 in 1 Card Reader plugged into new PCI based USB-2 port:
>
> Read = 0.59 / Write = 4.23;
> ==============================================

The read operation from USB 1.1 to USB 2.0 improved by 2.30/0.59 = 2.3 times.
You either got your data or your conclusion backward.

And if both will transfer writes at 4.38 & 4.23 I don't see how a difference of 0.59 to 2.30 can have anything to do with the bus speed.

When you get your USB 1 & 2 numbers sorted out, one of the write speeds is still going to exceed USB1 theoretical capability.

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