# WD Passport HDD - any experiences?



## googlefish (Jun 21, 2005)

Just got the WD Passport 160GB HD from Costco. It's a USB Powered 2.5" mobile drive that just won't work on my 12" iBook (1.33Ghz). It does work on a Windows machine though. Anyone with a similar experience or has anyone got one of these working on an iBook.

Read that these don't work well with PowerBooks but not too many stories of not working with iBooks.

Any thoughts?


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## krs (Mar 18, 2005)

It has to be a power issue. If it doesn't work well with powerbooks, it surely won't work on an ibook.

I read this on CNET



> After purchasing the HD, I plugged it in and to my supprise it was not working. After some research on WD's website I quickly found out that most laptops will not power up this hardrive, as it draws more power than USB drives are allowed to supply in specs. They stated you need to buy a power source from thier website. This compltetly took the portability away from this drive. Super bummer. Thank god I was able to return it. I ended up getting the LaCie 160GB with USB 2.0 and firewaire. Started up, no problem! My computer is a Powerbook G4 for your reference.


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## krs (Mar 18, 2005)

It is definitely a power issue - and a big one at that.
The drive requires a bit over 1000ma to spin up - the USB standard (last time I looked) required a powered USB port to provide 500ma or better.
WD is out in left field with this product - one of their solutions is to buy an external power adapter, the other is to buy a special USB cable that connects to both your USB ports and can thus get enough power, 500ma from each.
The correct solution is to ditch the drive and get one that meets industry specs.

This is from the WD website


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## googlefish (Jun 21, 2005)

Disappointed - it's supposed to be Mac compatible. It's strange that it works on my Sony notebook that's 5 years old on USB 1.0


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## krs (Mar 18, 2005)

Just to make sure nothing had changed, I just looked at the latest spec on usb.org.

This is the introduction to the various USB hub and port concepts. 500ma or "5 unit loads" (at 100ma per unit is the requirement. WD is way off base here - interestingly enough they don't specify the current requirement under "Specs" for these drives and really downplay the issue.


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## krs (Mar 18, 2005)

googlefish said:


> Disappointed - it's supposed to be Mac compatible. It's strange that it works on my Sony notebook that's 5 years old on USB 1.0


Ironically enough probably because the ibook is a more sophisticated design than the 5-year old notebook.
These things sometimes backfire.

How many USB ports does your Sony notebook have? I assume at least two, maybe more.
Scenario A
To keep costs down, the older computers, Mac included, used a single USB controller for both ports - cheaper that way than one controller per port. The controller had no trouble keepting up with USB 1.1 speeds.
As for the power - the spec was 500ma minimum per port, so if I designed a 1 amp (1000ma) power feed to drive both ports in parallel, I would meet the spec.
The user can plug a 500ma USB device into each port - everything is great.

Scenario B
Firewire comes along and in response the USB folks need to up the speeds to be competitive. USB 2.0 is developed to provide 480 M peak speeds, outperforming firewire 400 at least on paper. But with the technology at the time, a single chip couldn't andle both USB 2.0 port, so an individual chip had to be rovided for each port. Power requirement is still 500ma minimum and that's what each 2.0 powered USB port provides. But they are individual ports now - the power is not paralled.
The user can plug a 500ma USB device into each port - everything is great.
Same as scenario A.

Well yes - as long as the connected device also follows the USB spec.

But for the WD drive, if you plug it into a USB port in scenario A, it can actually draw the 1000ma it requires, wheras in scenario B it can't and you have the problem you encounter.
In practice, a USB port will provide a bit more than the 500ma, the 500ma spec is the absolute minimum, but it sure won't be designed to provide 1000ma, especially on a notebook.

Does the WD drive actually have a USB logo on it? It shouldn't since it doesn't meet the USB spec.


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