[X4U] iPad news

David Ledger dledger at ivdcs.demon.co.uk
Mon Feb 1 01:16:40 PST 2010

At 13:18 -0500 31/1/10, Neil Laubenthal wrote:
>On Jan 31, 2010, at 8:51 AM, David Ledger wrote:
>>  One of the problems with a USB port is that the standard says it 
>>has to be able to supply 0.5A to a plugged in device. This would 
>>play havoc with the 10hr battery life.
>>  A camera always has battery power at least, and so doesn't require 
>>any of that 0.5A. Maybe calling something a camera port means it 
>>doesn't have to be full spec USB.
>You could be right . . .although with the short time a device would 
>be hooked up it might not suck down all that much battery capacity. 
>I would think a flash drive would be pretty low draw . . .but 
>something like a laptop drive might pull more. I checked and the 
>startup draw is listed (for the Seagate I looked at) 1 amp max and 
>then a max of 3 watts during seek. So running that drive for 10 
>minutes would consume maybe 1 watt hour total . . .with a 25 watt 
>hour battery in the iPad that does suck down the battery some but 
>it's not like it would absolutely kill the battery for short usages.
>Just for grins . . .I pulled the MagSafe adapter on my MBP 3:30 
>remaining. Plugged in my usb drive and it went down to 2:30 (this is 
>a 7200 rpm drive which pulls more power than the 5400 above). 
>Granted the MBP has a 50 Watt hour battery instead of 25 . . .but it 
>doesn't look like short term running of a drive or flash drive would 
>crush the iPad battery.

The USB spec doesn't say 'for 10 minutes'. If it had a USB port for 
plugging a drive (of any sort) into, it would have to have to be able 
to supply 0.5A until the battery failed.  If they put a USB port on 
there there would be legal action because it couldn't drive a 0.5A 
disc and get anything like the 10 hour battery life. The anti-Apple 
brigade would have a field day. As far as I know a 'Camera Port' 
isn't a defined thing, so it can have whatever spec they like. In 
practice it may work with any USB device with its own power source, 
but connect it to anything other than a camera and you can't complain 
if it doesn't work or the battery life drops.

At 09:36 -0700 31/1/10, Marc Stergionis wrote:
>I'm confused. Can see from the photos that there is no bank of ports 
>on the iPad, but Apple's site on the Tech  Specs page lists In the 
>box: Dock connector to USB cable. Is that not a USB connection?

Yes, but think disc end, not computer end. A wire with a flat plug on 
it rather than the big square or mini plug.


David Ledger - Freelance Unix Sysadmin in the UK.
HP-UX specialist of hpUG technical user group (www.hpug.org.uk)
david.ledger at ivdcs.co.uk

More information about the X4U mailing list