Abstract:
An adaptive semiconductor memory device is used for being inserted into a host for storage. The semiconductor memory device comprises a non-volatile memory and a switch. The switch can be a logical switch or a physical switch that controls the semiconductor memory device to be in compliance with either a first specification version or a second specification version of the semiconductor memory device. The second specification version in comparison with the first specification version is used for higher capacity applications.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    (A) Field of the Invention 
         [0002]    The present invention is related to a semiconductor memory device, which is capable of changing the specification version thereof for providing flexibility in use. 
         [0003]    (B) Description of Related Art 
         [0004]    There are many kinds of memory cards sharing the same and similar forms; this situation confuses the users. Furthermore, these memory cards may need to use different file systems, increasing the complexity of use. 
         [0005]    According to Secure Digital (SD) specifications 1.0, 1.01 and 1.1, although the memory capacity of an SD card cannot exceed 2 gigabytes (GB), the SD card can communicate with a host of SD 1.0, 1.01, 1.1, 2.0 or above. For the capacity, the SD card is operated on a file system FAT (File Allocation Table)  16 . In  FIG. 1 , for example, a 1 GB SD card  11  in compliance with SD specification 1.1 is compatible with an SD 1.1 host system  12  and an SD 2.0, i.e., SDHC (Secure Digital High Capacity), host system  13 . 
         [0006]    According to SD specification 2.0 or above, i.e., SDHC, the capacity of an SD card can exceed 2 GB. However, this SD card is not compatible with the host of SD 1.0, 1.01 and 1.1, and needs to be operated on the file system FAT 32. In  FIG. 2 , for example, a 4 GB SD card  14  in compliance with SD specification 2.0 can communicate with the SD 2.0 (SDHC) host  13 , but is incompatible with the SD 1.1 host  12 . 
         [0007]    For an SD card of more than 2 GB, the corresponding host systems, e.g., a digital camera, a mobile phone, or a PDA, have to be in compliance with specification SD 2.0 or above. In other words, the SD card cannot communicate with a host of older specification version such as SD 1.0, 1.01 or 1.1. Therefore, the user may experience incompatibility between a larger capacity memory card of new specification version and older host systems. 
       SUMMARY OF THE INVENTION 
       [0008]    The present invention provides an adaptive semiconductor memory device, which is capable of changing the specification version thereof so as to provide flexibility in use. 
         [0009]    The present invention provides an adaptive semiconductor memory device used for being inserted into a host for storage. The semiconductor memory device comprises a non-volatile memory and a switch. The switch can be a logical switch or a physical switch that controls the semiconductor memory device to be in compliance with either a first specification version or a second specification version of the semiconductor memory device. The second specification version in comparison with the first specification version is used for higher capacity applications. 
         [0010]    For example, the memory device is an SD card, the first specification version is SD 1.0, 1.01 or 1.1, and the second specification version is SD 2.0. In an embodiment, the SD card may be provided with a physical switch, and the user can control the switch by hand to configure the SD card to be in compliance with SD 1.0, 1.01 or 1.1 or SD 2.0. Alternatively, the specification version of the SD card may be set by a computer through a card reader or according to the automatic detection of the specification version of the host. 
         [0011]    In addition to the change of the specification version, the file system of the semiconductor memory device may be changed accordingly. For example, FAT 16 is used for SD 1.0, 1.01 or 1.1, whereas FAT 32 is used for SD 2.0. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0012]      FIG. 1  and  FIG. 2  illustrate the compatibility problem for a memory device of the new specification version with a host of the old specification version; 
           [0013]      FIG. 3  and  FIG. 4  illustrate a semiconductor memory device in accordance with a first embodiment of the present invention; 
           [0014]      FIG. 5  illustrates a semiconductor memory device in accordance with a second embodiment of the present invention; 
           [0015]      FIG. 6  and  FIG. 7  illustrate a semiconductor memory device in accordance with a third embodiment of the present invention; 
           [0016]      FIG. 8  illustrates a semiconductor memory device in accordance with a fourth embodiment of the present invention; and 
           [0017]      FIG. 9  and  FIG. 10  illustrate the capacity allocations of the semiconductor memory device for different specification versions in accordance with the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0018]    Embodiments of the present invention will now be described with reference to the accompanying drawings. 
         [0019]    For an SD card of a capacity larger than 2 GB, because the version SD 1.0, 1.01 and 1.1 do not support SD cards of greater than 2 GB, the SD card has to use SD 2.0, i.e., SDHC, specification as a standard. For instance, if a host (an electronic apparatus), e.g., a digital camera, a mobile phone or a PDA, is in compliance with SD 1.0, 1.01 or 1.1, a traditional SD card of 4 GB cannot be inserted into the host. 
         [0020]    In accordance with an embodiment of the present invention, a card reader is provided to set the SD card to be in compliance with SD 1.0, 1.01 or 1.1 or SD 2.0. As shown in  FIG. 3 , a card reader  32  is used to receive an adaptive SD card  31  of the present invention. In this embodiment, the card reader  32  is provided with a USB interface  33  for being connected to a computer (not shown). The computer runs an “application (AP)” (a software) to configure the SD card  31  through the card reader  32  and the bus of the SD card  31 . In addition, AP also can be stored in the card reader  32 , the SD card  31  or the computer. 
         [0021]    The method to set the specification version of a standard is shown in  FIG. 4 . In Steps S 41  and S 42 , the user verifies whether the card reader is inserted into the computer and whether the SD card is inserted into the card reader. If the connections between the computer, the card reader and the SD card are ready, an application, e.g., windows AP, stored in the card reader, the adaptive SD card or the computer is popped (Step S 43 ). If the user wants to change the specification to SD 1.0, 1.01 or 1.1 (Step S 44 ), the application sends a command and changes the adaptive SD card into SD 1.0, 1.01 or 1.1 (Step S 45 ). If the user wants to change the specification to SD 2.0 or above, i.e., SDHC (Step S 46 ), the application sends a command and changes the adaptive SD card into SD 2.0 or above, i.e., SDHC (Step S 47 ). In addition to changing the specification version, in some cases the file system of SD card may need to be formatted to comply with the capacity. For example, the SD card of 1 GB uses the file system FAT 16, whereas the SD card of 4 GB uses the file system FAT 32. Therefore, if an SD card of 4 GB needs to be inserted into a host in compliance with SD 1.0, 1.01 or 1.1 (Step S 48 ), the file system is formatted to FAT 16 (Step S 49 ). 
         [0022]      FIG. 5  illustrates a second embodiment of the present invention. After the SD card  51  having an SD interface is inserted into a host  52  or  53 , the SD card  51  automatically detects the specification version of the host  52  or  53  and changes the specification version of the SD card accordingly. For example, if the host  52  is in compliance with SD 1.0, 1.01 or 1.1, the SD card  51  will automatically change to be in compliance with SD 1.0, 1.01 or 1.1 specification for a capacity less than 2 GB. Likewise, if the SD card  51  is inserted into the host  53  in compliance with SD 2.0 or above, the SD card  51  will automatically change to be of SD 2.0 or above for a capacity larger than 2 GB, i.e., SDHC. In addition, the adaptive SD card  51  may also be accordingly formatted to FAT 16, FAT 32 or others during its next boot up after the specification version is changed. 
         [0023]      FIG. 6  illustrates a third embodiment of the present invention. An SD card  61  is provided with a physical switch  62  to change the mode of the SD card. For example, the switch  62  can switch between two modes, a capacity mode and a capability mode. If the switch  62  is in the capacity mode, the SD card  61  is in compliance with SD 2.0 or above and is of a capacity greater than 2 GB. If the switch  62  is in the capability mode, the SD card  61  is in compliance with SD 1.0, 1.01 and 1.1 and is of a capacity equal to or less than 2 GB. Accordingly, the mode of the SD card  61  can be changed by the switch  62 . Moreover, the SD card  61  can be automatically formatted to FAT 16, FAT 32 or another file system during its next boot up after the SD card  61  has changed the specification version. 
         [0024]    More specifically, the change of specification version by a switch is shown in  FIG. 7 . First, it is verified whether the SD card is inserted into an accessible host (Step S 71 ). If the SD card is inserted into the host, it is detected whether the mode is changed by the switch (Step S 72 ). If so, the SD card is changed to SD 1.0, 1.01, 1.1 or SD 2.0 (Step S 73 ). If the card requires a change of the file system (Step S 74 ), the SD card is formatted by itself to change the file system accordingly (Step S 75 ). 
         [0025]    In addition to the above embodiments, the people having ordinary knowledge can implement in other ways. For example, an SD card  80  is provided with two interfaces in which a first interface  81  is in compliance with SD 1.0, 1.01 and 1.1 and a second interface  82  is in compliance with SD 2.0 as shown in  FIG. 8 . Accordingly, the user can select a proper interface to be inserted into the host. 
         [0026]    If an SD card has 8 GB, the capacity can be divided in two ways. As shown in  FIG. 9 , when the SD card is set to SD 1.0, 1.01 or 1.1, the SD card provides 2 GB for storage (2 GB mode). When the SD card is set to SD 2.0 or above, i.e., SDHC, the SD card provides 8 GB for storage (8 GB mode). There is an overlap between SD 1.0/1.01/1.1 and SD 2.0; the data of overlap area may need to be stored by a host first and copied to the SD card after mode change. However, the data of the overlap area may be erased directly if doing so is deemed suitable. 
         [0027]    In some cases, the data stored in the SD card need not be erased. As shown in  FIG. 10 , when the SD card is set to SD 1.0, 1.01 or 1.1, the SD card provides 2 GB of storage (2 GB mode). When the SD card is set to SD 2.0 or above, i.e., SDHC, the SD card provides 6 GB of storage (6 GB mode). There is no overlap between SD 1.0/1.01/1.1 and SD 2.0, therefore it is not necessary to duplicate the data before the mode switch. 
         [0028]    The SD card of SD 2.0 specification is incompatible with the old version specification such as SD 1.0, 1.01 or 1.1. Without the present invention, the new SD card of SD 2.0 or above cannot be used for older digital cameras, mobile phones or PDAs. In accordance with the present invention, however, the high capacity SD card of the specification SD 2.0 or above still can communicate with the hosts of SD 1.0, 1.01 and 1.1. In other words, the new SD card with new version of specification can still be used in the electronic apparatuses of old specification, thereby providing superior flexibility in use. 
         [0029]    The memory devices are not limited to SD cards, other devices such as CF cards, memory sticks, etc. will be also covered by the scope of the present invention if they substantially implement the present invention. 
         [0030]    The above-described embodiments of the present invention are intended to be illustrative only. Numerous alternative embodiments may be devised by those skilled in the art without departing from the scope of the following claims.