linguistics.. i see i see!  咁你個 course 深好多!  

我諗 2.5/3.5 都可以算係 portable 既，只要可以方便拎黎拎 (唔洗拆螺絲嗰啲)，都應該可以列為 "portable" 既，不過比較起黎 2.5 比 3.5 方便少少因為少條 power cable..

Here's a list of SATA docking stations for 2.5/3.5 internal hdd.  The idea is to take advantage of cheaper internal hdd.  But honestly, the external hdd prices are quite reasonable nowadays too.http://www.amazon.com/s/?ie=UTF8 ... =pd_sl_90u94p5nvc_b

I have an old Sony HD which needs 2 USB cable...so that is 3.5?

ben, we were talking about the hdd size 2.5" or 3.5".. I think most 3.5" are powered by an ac adaptor plugging to an outlet, while most 2.5" external hdd are powered by the computer that it plugs into.  I never heard of a hdd that needs 2 USB cables.. do you know why it needs 2 USB cables?  

Oh....sorry.  I should say it this way.  My old Sony external HD comes with a USB cable which is (one small USB which plug to the HD, the other side of the cable which has 2 USB plug head)  So I prefer one is for power and the other one is for data.  If i use the normal USB cable (which has only one plug on each side)...side the HD doesn't work.  

ben, i see i see.. so it is a 3.5" but does not require a power cable, and instead, it plugs into two USB ports on the computer, one for data and one for power?

Yes, it doesn't require a power cable.  But it needs to plug into 2 USB ports.  So as i said, i prefer 1 is for data, the other is for power.

ben, then it is convenient woh..   do they have that for all the newer 3.5" external hdd now?

Convenient?  Personally...i don't like it.  Because 1) Need a special USB cable.  If you forget to bring it with you, then you can't use your HD.  Other people don't have that kind of USB cable that you need.  2)  It will waste a USB port on your netbook....like my mom's netbook.  Only has 3 USB ports.  One for mouse (She doesn't like to use the pad), one for her Chinese hand writing pad.....then only one left....she can't use my Sony external HD then.....