[AlbanianGenome]

So i have this 320 gig external Western Digital USB 2 drive that has been working fine on all my machines up until the other day when I purchased an older powerpc laptop. I plug it in, and nothing, nothing shows up on the desktop, nothing shows in disk utility. I try both usb ports, and still nothing. This is a 1.5ghz Powerbook G4 laptop which it is not working on. I can plug a mouse in with no problem, so the usb bus is working, so I thought it doesnt have usb 2.0, but I checked and the specs say it does. I plug the hard drive into the intel macbook and it shows up just fine. What is going on here? It also does not get recognized by my windows pc that has usb 2.0 as well. I would love any thoughts on this as I am completely perplexed. THanks!

[reader50]

What OS version is on the PowerBook? On the HD side, what file system and partition scheme does it use?

[AlbanianGenome]

10.4.11 on the Powerbook, and I even transfered my information over to another hard drive and wiped it with disk utility and still not being recognized, formated with mac os extended(journaled). I can't for the life of me figure it out, it is very strange.

[ibook_steve]

The older machine is not supplying enough power through its USB ports to power the external drive. You'll need a powered USB hub or an AC adapter for the drive itself (if it supports one) to make it work.

Steve

[AlbanianGenome]

ibook_steve, thank you, how does that work though? I thought if a computer has USB 2.0 they should be able to power any usb 2.0 drive. Did not realize that older computer cannot power a usb drive drive with no power adapter. I did not think about that at all, thanks for the heads up, I am taking it into apple today anyhow to see what this is all about.

[ibook_steve]

Just because a port is USB 2.0 doesn't mean it will supply enough power for a device. I don't recall what the minimum required supplied power spec is for the USB 2.0 standard, but when it was decided, it was more than enough for mice, keyboards, USB flash drives, etc. Now that everything uses USB, more power is required for things like external hard drives. Older machines simply weren't designed to provide enough juice, though the OS should give a warning message about this (I thought it used to, but I haven't seen the message recently when I've had the same issue you've run into). Some drives come with an AC adapter or even a special USB cable with two USB connectors to connect to two separate ports to get enough power.

Steve

Edit: Just for reference, here's part of the USB entry about power from Wikipedia. I don't know how many "unit loads" your old machine puts out, but it's obviously not enough. USB 3.0 will make life much easier (until even more power-hungry devices are used):

The USB specification provides a 5 V supply on a single wire from which connected USB devices may draw power. The specification provides for no more than 5.25 V and no less than 4.75 V (5 V±5%) between the positive and negative bus power lines.[19]

A unit load is defined as 100 mA in USB 2.0, and was raised to 150 mA in USB 3.0. A maximum of 5 unit loads (500mA) can be drawn from a port in USB 2.0, which was raised to 6 (900 mA) in USB 3.0. There are two types of devices: low-power and high-power. Low-power devices draw at most 1 unit load, with minimum operating voltage of 4.4 V in USB 2.0, and 4 V in USB 3.0. High-power devices draw the maximum number of unit loads supported by the standard. All devices default as low-power but the device's software may request high-power as long as the power is available on the providing bus.[20]

A bus-powered hub is initialized at 1 unit load and transitions to maximum unit loads after hub configuration is obtained. Any device connected to the hub will draw 1 unit load regardless of the current draw of devices connected to other ports of the hub (i.e one device connected on a four-port hub will only draw 1 unit load despite the fact that all unit loads are being supplied to the hub).[20]

A self-powered hub will supply maximum supported unit loads to any device connected to it. A battery-powered hub may supply maximum unit loads to port. In addition, the VBUS will supply 1 unit load upstream for communication if parts of the Hub are powered down.[20]

In Battery Charging Specification, new powering modes are added to the USB specification. A host or hub charger can supply maximum 1.5 A when communicating at low-speed or full-speed, maximum 900 mA when communicating at hi-speed, no upper current limit when no communication is taking place. A dedicated charger can supply maximum 1.5 A of current. A portable device can draw up to 1.8 A from a dedicated charger. The dedicated charger shorts the D+ and D- pins together and will not send or receive any information on those lines, allowing very simple, high current chargers to be manufactured. The increased current (faster charging) will occur once the host/hub and devices both support the new charging specification.