[Wylug-discuss] Powered USB [WAS: Recommendation: Linux-compatible Netbook Under GBP 250?]

[Paul Brook]

> Sorry to be so ignorant, but are many netbooks crippled by the
> inability to power external usb devices?
> 
> Or am I being unduly pessimistic?

AFAIK, not any worse than your average cheapo laptop.

Note that "powerd USB" may mean different things to different people.  
Standard USB allows 2.5W per port.  This should be fine.

I suspect you're thinking ot some devices that used an unpowered hub to 
provide their USB ports.  These can only supply 0.5W/port,
.  Enough for mice, but not more power hungry devices like 3G dongles or 
harddrives.  Manufacturers caught on fairly quickly that this was a terrible 
idea and I haven't seen it recently.

Some devices (typically large spinning disks) draw more USB power then they're 
allowed to, especially at startup.  Typically these come with evil "Y" 
splitter cables to spread the load.  If you're running multiple of these you 
may exceed the total USB power available on the machine.  I guess slightly 
more likely to occur with a netbook given they have less ports total, but 
relatively easy to workaround (powered hub) and really not a fault in the 
netbook - the USB spec says that hosts can/should deliberately cut off devices 
that draw too much power.

The other feature is a "charging" port that stays powered when the machine is 
turned off.  Support entirely depends on the device, my guess is fairly rare 
on netbooks.

Paul