PDA

View Full Version : USB 3.0 and 2.0




onthecouchagain
Nov 13, 2012, 11:14 PM
Question: I have an old MacBook Air that has USB 2.0's... can I still buy an external hard drive that uses USB 3.0? The wires that come with the ext HD will still fit and work with my Mac?

Yes? I'm a little confused by the "direction" of the backwards compatibility.

Thanks in advance.



MacPat333
Nov 13, 2012, 11:40 PM
You can do so only if the external harddrive is compatible with USB 2.0 as well as 3.0.

If it only runs USB 3.0 it won't work with your MBA!

flyguy206
Nov 13, 2012, 11:42 PM
Yes it will work but at USB 2.0 speeds

old-wiz
Nov 14, 2012, 11:29 AM
All USB 3.0 products are supposed to be backwards compatible with USB 2.0; there should be no problem using any USB 3.0 product with USB 2.0.

onthecouchagain
Nov 14, 2012, 02:37 PM
Thanks, y'all.

KylePowers
Nov 14, 2012, 04:23 PM
You can do so only if the external harddrive is compatible with USB 2.0 as well as 3.0.

If it only runs USB 3.0 it won't work with your MBA!
Architecture and features
In USB 3.0 dual-bus architecture is used to allow both USB 2.0 (HIGH Speed/LOW Speed/FULL Speed) and USB 3.0 (Super Speed) operations to take place simultaneously, thus providing backward compatibility. Connections are such that they also permit forward compatibility, that is, running USB 3 devices on USB 2.0 ports. The structural topology is the same, consisting of a tiered star topology with a root hub at level 0 and hubs at lower levels to provide bus connectivity to devices.
http://en.wikipedia.org/wiki/USB_3.0