Abstract:
An external storage device includes a hard-drive, a flash memory, and a memory arrangement unit. The memory arrangement determines if the tag of the data accessed by a computer stored in the tag list of the memory arrangement unit and controls the hard-drive and the flash memory according to the result of the determination.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The present invention provides a storage device, and more particularly, an external storage device. 
         [0003]    2. Description of the Prior Art 
         [0004]    Please refer to  FIG. 1 .  FIG. 1  is a diagram illustrating a conventional external storage device  102 . The external storage device  102  can be a Serial Advanced Technology Attachment (SATA) hard-drive, and coupled to a computer through an External SATA (eSATA) interface. In this way, the computer  101  transmits data to the external storage device  102  for storing data in the external storage device  102  or reads data from the external storage device  102  through the eSATA interface. 
         [0005]    The drawback of the conventional external storage device  102  is the reading speed of the hard-drive being too slow. Consequently, if the computer  101  stores data which is frequently used in the conventional external storage device  102 , when the computer  101  reads that data stored in the hard-drive, the computer has to wait, which is time-wasting. For example, the OS Window Vista can store programs for initiation in external devices. If the programs for initiation are stored in the external storage device  102 , the time consumed by the initiation of the OS is too long due to the slowness of the hard-drive, causing inconvenience. 
       SUMMARY OF THE INVENTION 
       [0006]    The present invention provides an external storage device. The external storage device comprises a hard-drive for accessing data; a flash memory for accessing data; a memory arrangement unit for reading a tag of data accessed by a computer, determining if the tag is in a tag list of the memory arrangement unit, and accordingly controlling the hard-drive or the flash memory to access data with the computer. 
         [0007]    These and other objectives of the present invention will no doubt become obvious to those of ordinary skill in the art after reading the following detailed description of the preferred embodiment that is illustrated in the various figures and drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0008]      FIG. 1  is a diagram illustrating a conventional external storage device. 
           [0009]      FIG. 2  is a diagram illustrating the external storage device of the present invention. 
           [0010]      FIG. 3  is a flowchart illustrating the method of the external storage device of the present invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0011]    Please refer to  FIG. 2 .  FIG. 2  is a diagram illustrating the external storage device  200  of the present invention. As shown in  FIG. 2 , the external storage device  200  comprises a memory arrangement unit  201 , a hard-drive  202 , and a flash memory. The memory arrangement unit  201  is coupled to the computer through an eSATA interface. The memory arrangement unit  201  is also coupled to the hard-drive  202  and the flash memory  203 . Additionally, the hard-drive  202  and the flash memory  203  are both detachable for convenience. 
         [0012]    The flash memory  203  has faster accessing speed than the hard-drive  202  does. Therefore, the initiation time of the computer  101  can be shortened by utilizing the flash memory  203  for accessing initiation programs. However, the memory size of the flash memory  203  is much less than that of the hard-drive  202 . Thus, the memory arrangement unit  201  has to efficiently distribute the locations of data to be stored. That is, the data frequently used is stored in the flash memory  203 , and the data rarely used is stored in the hard-drive  202 . The spirit of the present invention is: when the computer  101  stores data in the external storage device  200 , the flash memory  203  is provided to accelerate the initiation of the computer  101 . 
         [0013]    The memory arrangement unit  201  comprises a tag list for indexing the priority of the data. For example, if the data A is frequently accessed, the tag of the data A has higher priority in the tag list. On the other hand, if the data A is rarely accessed, the tag of the data A has lower priority in the tag list, or the tag of the data A is not in the tag list. The present invention uses such manner to control the priority of the data. 
         [0014]    In this way, the initiation time of the computer  101  can be shortened by utilizing the external storage device  200 . After the initiation of the computer  101 , the external storage device  200  can also provide data storage to the computer  101 , increasing the convenience. 
         [0015]    Please refer to  FIG. 3 .  FIG. 3  is a flowchart illustrating the method  300  of the external storage device of the present invention. The steps are described as follows: 
         [0016]    Step  301 : Start; 
         [0017]    Step  302 : The computer  101  transmits a data accessing command; 
         [0018]    Step  303 : The memory arrangement unit  201  reads the tag of the data to be accessed; 
         [0019]    Step  304 : The memory arrangement unit  201  determines if the tag is in the tag list of the memory arrangement unit; if yes, go to step  3051 ; if no, go to step  3052 ; 
         [0020]    Step  3051 : The memory arrangement unit  201  determines if the data is to be read or to be stored; if the data is to be read, go to step  3061 ; if the data is to be stored, go to step  3062 ; 
         [0021]    Step  3052 : The memory arrangement unit  201  determines if the data is to be read or to be stored; if the data is to be read, go to step  3071 ; if the data is to be stored, go to step  3072 ; 
         [0022]    Step  3061 : The memory arrangement unit  201  writes data into the flash memory  203 , go to step  310 ; 
         [0023]    Step  3062 : The memory arrangement unit  201  reads data from the flash memory  203 , go to step  310 ; 
         [0024]    Step  3071 : The memory arrangement unit  201  determines if the space left in the flash memory  203  is lower than a threshold; if yes, go to step  3091 ; if not, go to step  3081 ; 
         [0025]    Step  3072 : The memory arrangement unit  201  determines if the space left in the flash memory  203  is lower than a threshold; if yes, go to step  3092 ; if not, go to step  3082 ; 
         [0026]    Step  3081 : The memory arrangement unit  201  transfers the data, having lower priority in the tag list and stored in the flash memory  203 , to the hard-drive  202 ; 
         [0027]    Step  3082 : The memory arrangement unit  201  transfers the data, having lower priority in the tag list and stored in the flash memory  203 , to the hard-drive  202 ; 
         [0028]    Step  3091 : The memory arrangement unit  201  reads data from the hard-drive  202  and makes a copy in the flash memory  203 , go to step  310 ; 
         [0029]    Step  3092 : The memory arrangement unit  201  writes the data into the flash memory  203  and the hard-drive  202 , go to step  310 ; 
         [0030]    Step  310 : End. 
         [0031]    The hard-drive  202  and the flash memory  203  of the external storage device  200  of the present invention are detachable for providing users easier ways to change the storage components. 
         [0032]    Additionally, the hard-drive  202  of the present invention can be Serial Advanced Technology Attachment (SATA) or Parallel Advanced Technology Attachment (PATA) interface. 
         [0033]    Those skilled in the art will readily observe that numerous modifications and alterations of the device and method may be made while retaining the teachings of the invention.