what is the External Harddisk or Portable Harddisk do

External storage This means that the media that is used to store data is from the main memory in the computer, such as the tape, disk, because it is much cheaper. I will not turn on the lights. The main memory in the computer is not enough to put a lot of data into it. (Even bigger To save money, we may store data in secondary memory. This or auxiliary storage is first retrieved into the main memory only when the time it needs to run has the same meaning as external memory, secondary memory, and auxiliary storage. External Harddisk or Portable Harddisk A computer storage device that can be portable or portable. Also, places using a harddisk are commonly used on computers. To install in the box to put Harddisk, there is a board of control of the Harddisk installed in the box. You can choose the size of Harddisk installed in this box to meet the needs and type of Harddisk to be installed in this box. Must be correct with the type of box, there are two types are generally IDE or SATA, but now it is starting to have both e-SATA and then. Including the latest USB 3.0 data transfer technology recently launched recently. For the size of the External Harddisk, there are two types of Harddisk that come from the desktop. This will require a larger case because the ball will be bigger and will need to be bigger. External power supply is also required. Another is to bring the notebook harddisk to put on the circuit board. It is not necessary to use external power supply and is smaller, portable, but has a higher price than the large enough. Interface to the computer will use a USB cable through a USB port, usually with two USB cables, one line is a cable to receive power from the USB port on the computer to power. To the controller Harddisk in the box External Harddisk Box or Case and Harddisk installed in the box. Another line will be the input and output channel. It will connect to the active computer.