Patent Publication Number: US-7917531-B2

Title: Information processing apparatus

Description:
TECHNICAL FIELD 
     The present invention relates to an information processing apparatus, and particularly to an information processing apparatus for handling data relevant to copyright protected content. 
     BACKGROUND ART 
     Personal computers and portable devices for handling copyright protected content are used. 
     A personal computer having content recorded therein is able to check out copyright protected content to a portable device based on the right of checkout. 
     The portable device is carried for use, and plays back the checked out content at a desired location. 
     As far as the copyright allows, content can be checked out to a portable device of another user so that the user can use the checked out content. 
     However, except for an approach such as inquiring acquaintances frequently, it is impossible to know the presence or details of content which others are allowed to check out. 
     DISCLOSURE OF INVENTION 
     The present invention has been made in view of such a background, and it is an object of the present invention to allow users to easily know content which others are allowed to check out. 
     An information processing apparatus of the present invention includes first recording control means for controlling recording of data relevant to content which others are allowed to check out; first reception control means for controlling reception of a request for the data relevant to the content; and transmission control means for controlling transmission of the data relevant to the content when the data relevant to the content is requested. 
     The first recording control means may control recording of the data relevant to the content in which a checkout limit is set. 
     The information processing apparatus may further include second recording control means for controlling recording of billing information for a user who is one of the others; and billing process performing means for performing a process for charging the user based on the recorded billing information when the data relevant to the content is transmitted as requested from the user. 
     The information processing apparatus may further include second recording control means for controlling recording of the content; second reception control means for controlling reception of a request to check out the content; and checkout control means for controlling checkout of the recorded content when a checkout of the content is requested. 
     The second recording control means may control recording of the content in which a checkout limit is set. 
     The information processing apparatus may further include third recording control means for controlling recording of billing information for a user; and billing process performing means for performing a process for charging the user based on the recorded billing information when the data relevant to the content is transmitted or the content is transmitted as requested from the user. 
     The information processing apparatus may further include third recording control means for controlling recording of a checkout history of the content. 
     An information processing method of the present invention includes a recording control step of controlling recording of data relevant to content which others are allowed to check out; a reception control step of controlling reception of a request for the data relevant to the content; and a transmission control step of controlling transmission of the data relevant to the content when the data relevant to the content is requested. 
     A program in a program storage medium of the present invention includes a recording control step of controlling recording of data relevant to content which others are allowed to check out; a reception control step of controlling reception of a request for the data relevant to the content; and a transmission control step of controlling transmission of the data relevant to the content when the data relevant to the content is requested. 
     A program of the present invention causes a computer to execute a recording control step of controlling recording of data relevant to content which others are allowed to check out; a reception control step of controlling reception of a request for the data relevant to the content; and a transmission control step of controlling transmission of the data relevant to the content when the data relevant to the content is requested. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a block configuration diagram showing an embodiment of a content providing system according to the present invention. 
         FIG. 2  is an external view of a personal computer  1 . 
         FIG. 3  is an external view of the personal computer  1 . 
         FIG. 4  is an external view of the personal computer  1 . 
         FIG. 5  is an external view of the personal computer  1 . 
         FIG. 6  is a block diagram showing an example of the configuration of the personal computer  1 . 
         FIG. 7  is a block diagram showing an example of the configuration of a portable device  2 . 
         FIG. 8  is a block diagram showing an example of the configuration of a memory card  3 . 
         FIG. 9  is a diagram showing the functional structure of a server  5 . 
         FIG. 10  is a view showing an exemplary screen displayed by a personal computer  1 - 2  when setting a checkout period. 
         FIG. 11  is a view showing exemplary conditions of use. 
         FIG. 12  is a flowchart illustrating a registration process. 
         FIG. 13  is a flowchart illustrating a process for recording information on content. 
         FIG. 14  is a flowchart illustrating a checkout process. 
         FIG. 15  is a flowchart illustrating an automatic check-in process for content performed by the portable device  2 . 
         FIG. 16  is a flowchart illustrating an automatic check-in process performed by the personal computer  1 - 2 . 
         FIG. 17  is a configuration diagram showing another embodiment of the content providing system. 
         FIG. 18  is a block diagram showing an example of the configuration of a portable device  401 . 
         FIG. 19  is a configuration diagram showing still another embodiment of the content providing system. 
         FIG. 20  is an external view of a camera-equipped digital cellular telephone set  501 . 
         FIG. 21  is an external view of the camera-equipped digital cellular telephone set  501 . 
         FIG. 22  is a block diagram showing the configuration of the camera-equipped digital cellular telephone set  501 . 
         FIG. 23  is a flowchart illustrating a content checkout process. 
         FIG. 24  is a configuration diagram showing still another embodiment of the content providing system. 
         FIG. 25  is a configuration diagram showing still another embodiment of the content providing system. 
         FIG. 26  is a diagram showing the functional structure of a server  701 . 
         FIG. 27  is a view showing an exemplary screen displayed by the personal computer  1 - 2  when content is moved to the server  701 . 
         FIG. 28  is a view showing exemplary data indicating a log of checkouts. 
         FIG. 29  is a view showing exemplary data indicating the details of content. 
         FIG. 30  is a flowchart illustrating a content moving process. 
         FIG. 31  is a flowchart illustrating a content checkout process. 
         FIG. 32  is a configuration diagram showing still another embodiment of the content providing system. 
         FIG. 33  is a flowchart illustrating a content checkout process. 
     
    
    
     BEST MODE FOR CARRYING OUT THE INVENTION 
       FIG. 1  is a block configuration diagram showing an embodiment of a content providing system according to the present invention. 
     A personal computer  1 - 1  issues a request to check out content, in which a checkout period is set, to a personal computer  1 - 2  over a network  4  such as the Internet or a local area network based on data indicating the details or location of the content provided from a server  5 . 
     Content recorded in the personal computer  1 - 2 , and checkout and check-in operation are described below. 
     The personal computer  1 - 2  converts content which is music/sound data received from an EMD (electrical music distribution) server (not shown) connected to the network  4  or read from a CD (compact disc) or the like into predetermined compression format (for example, ATRAC3 (trademark)) data, and also encodes the resulting data using an encryption technique such as DES (data encryption standard) before recording the data. 
     The personal computer  1 - 2  records, in correspondence with the encoded and recorded content, conditions-of-use data which represents conditions of use of the content. 
     The conditions-of-use data indicates, for example, the number of portable devices (also referred to as “PDs”)  2  which can simultaneously use the content corresponding to the conditions-of-use data (the number of PDs which can so-called check out the content, as discussed below). Even when the content is checked out to the number of devices which is included in the conditions-of-use data, the personal computer  1 - 2  can play back the content. 
     The conditions-of-use data also indicates that the content can be copied. There may be sometimes limits placed on the number of copies for the content. In this case, the number of copies does not increase. 
     The conditions-of-use data also indicates that the content can be moved to another personal computer, a server, or the like. After being moved to another personal computer or a server, the content recorded in the personal computer  1 - 2  is not available (the content is deleted, or the conditions of use are modified to make the content unavailable). 
     Upon a request from the personal computer  1 - 1 , the personal computer  1 - 2  performs a so-called checkout process to cause the encoded and recorded content to be stored into a memory card  3  attached to the portable device  2  over the network  4  and via the personal computer  1 - 1  together with data relevant to the content (for example, the title of a song, playback conditions, and so on) and to update the conditions-of-use data corresponding to the stored content as the content is stored in the memory card  3 . 
     More specifically, the number of checkouts allowed in the conditions-of-use data corresponding to the content recorded in the personal computer  1 - 2  decrements by one each time the content is checked out. If the number of checkouts allowed is zero, the corresponding content cannot be checked out. 
     The personal computer  1 - 2  further performs a so-called check-in process to, as the content checked out to the memory card  3  by the personal computer  1 - 2  is erased by the portable device  2 , update the conditions-of-use data corresponding to the erased content. More specifically, the number of checkouts allowed in the conditions-of-use data corresponding to the content recorded in the personal computer  1 - 2  increments by one each time the content is checked in. 
     The personal computer  1 - 1  transmits the content checked out from the personal computer  1 - 2  to the portable device  2  connected to the personal computer  1 - 1  via a USB (universal serial bus) or the like. The portable device  2  stores the content received from the personal computer  1 - 1  into the memory card  3  attached thereto. 
     When the checkout period set in the conditions of use corresponding to the content has passed, the portable device  2  erases the content stored in the memory card  3 . A content erasing process performed by the portable device  2  based on the checkout period is also hereinafter referred to as an automatic check-in process of the portable device  2 . 
     The personal computer  1 - 2  sets a checkout period in the content recorded therein, and transmits to the server  5  over the network  4  data indicating the details of the content in which the checkout period is set, content ID of the content in which the checkout period is set, and data indicating the location in which the content in which the checkout period is set is stored. The data indicating the location in which the content is stored is constructed by, for example, URL (uniform resource locator), IP (Internet protocol) address, drive name, directory name, folder name, or the like. 
     The personal computer  1 - 2  increments the number of checkouts allowed by one when the checkout period set in the conditions of use corresponding to the content checked out to the memory card  3  has passed. A process for incrementing the number of content checkouts allowed based on a checkout period which is performed by the personal computer  1 - 2  is also hereinafter referred to as an automatic check-in process of the personal computer  1 - 2 . 
     The server  5  records the data indicating the details of the content in which the checkout period is set, the content ID of the content in which the checkout period is set, and the data indicating the location in which the content in which the checkout period is set is stored, which are received from the personal computer  1 - 2 . 
     When the data relevant to the content is requested from the personal computer  1 - 1 , the server  5  transmits to the personal computer  1 - 1  the data indicating the details of the content in which the checkout period is set, the content ID of the content in which the checkout period is set, and the data indicating the location in which the content in which the checkout period is set is stored, which are recorded in the server  5 . 
     The personal computer  1 - 1  displays the details of the content in which the checkout period is set based on the data indicating the details of the content in which the checkout period is set. Upon a user operation of selecting content to be checked out based on the displayed details, the personal computer  1 - 1  issues a content checkout request to the personal computer  1 - 2  based on the content ID of the content in which the checkout period is set and the data indicating the location in which the content in which the checkout period is set is stored. 
     If it is not necessary to individually identify the personal computers  1 - 1  and  1 - 2 , they are hereinafter referred to simply as a personal computer  1 . 
       FIGS. 2 through 5  are external views of the personal computer  1  constructing the content providing system according to the present invention. The personal computer  1  is basically formed of a body  21 , and a display unit  22  which is openable and closable with respect to the body  21 .  FIG. 2  is an external perspective of the personal computer  1 , showing that the display unit  22  is open with respect to the body  21 .  FIG. 3  is a plan view of the body  21 , and  FIG. 4  is an enlarged view of a jog dial  23  described below which is disposed on the body  21 .  FIG. 5  is a side view of the jog dial  23  disposed on the body  21 . 
     A keyboard  24  operated to enter various characters or symbols, a touch pad  25  serving as a pointing device operated to move a pointer (mouse cursor) displayed on an LCD (liquid crystal display)  26 , and a power switch  27  are disposed on the top surface of the body  21 . A jog dial  23 , a slot  28 , an IEEE (Institute of Electrical and Electronics Engineers) 1394 port  101 , a memory card slot  115 , and so on are disposed on a side surface of the body  21 . A stick-type pointing device may be disposed in place of the touch pad  25 . 
     The LCD  26  for displaying an image is disposed on the front surface of the display unit  22 . A power lamp PL, a battery lamp BL, a message lamp ML (not shown), if necessary, and other LED lamps are disposed on the upper right portion of the display unit  22 . A microphone  66  is provided on the upper portion of the display unit  22 . 
     The power lamp PL, the battery lamp BL, the message lamp ML, etc., may be disposed on the lower portion of the display unit  22 . 
     The jog dial  23  is mounted, for example, between keys A and B of the keyboard  24  on the body  21 , as indicated in the right portion of  FIG. 3 , so that the top surface of the jog dial  23  is substantially coplanar to the keys A and B. The jog dial  23  performs predetermined processing (for example, scrolls on a screen) when rotated as indicated by an arrow “a” in  FIG. 4 , and performs processing corresponding to a motion indicated by an arrow “b” in  FIG. 4  (for example, selects an icon). 
     The jog dial  23  may be placed on the left side surface of the body  21 , or on the left or right side surface of the display unit  22  incorporating the LCD  26 , or may be placed in the longitudinal orientation between the “G” and “H” keys of the keyboard  24  (that is, the jog dial  23  is rotated either toward the “Y” or “B” key). 
     Alternatively, the jog dial  23  may be placed at the center on the front surface of the body  21  so as to allow a user to operate the jog dial  23  using a thumb while operating the touch pad  6  using a forefinger. The jog dial  23  may be placed in the lateral orientation along the upper or lower edge of the touch pad  6 , or may be placed in the longitudinal orientation between the right and left buttons of the touch pad  6 . The orientation of the jog dial  23  is not limited to the longitudinal or lateral direction, and the jog dial  23  may be placed diagonally at a predetermined angle so as to allow a user to easily operate the jog dial  23  using fingers. Alternatively, the jog dial  23  may be placed at a portion on a side surface of a mouse serving as a pointing device which allows a user to operate the jog dial  23  using a thumb. The jog dial may be implemented by a push switch-equipped rotary operating electronic part disclosed in Japanese Unexamined Patent Application Publication No. 8-203387 filed by the present applicant and a co-applicant. 
     A PC card which is an extension card complying with the standard specified by PCMCIA (Personal Computer Memory Card International Association) is inserted into the slot  28 . 
     The IEEE 1394 port  101  has the structure complying with the standard specified in IEEE 1394, and a cable complying with the standard specified in IEEE 1394 is connected to the IEEE 1394 port  101 . 
     The memory card slot  115  has an internal semiconductor memory such as a flash memory, and the memory card  3  which is a memory card, such as a memory stick (trademark), for storing data such as still image, motion picture, audio, and text data is inserted into the memory card slot  115 . 
     An example of the configuration of the personal computer  1  is described below with reference to  FIG. 6 . 
     A central processing unit (CPU)  51  is implemented by, for example, Pentium (registered trademark) processor manufactured by Intel Corporation, and is connected to a host bus  52 . A bridge (so-called north bridge)  53  is also connected to the host bus  52 . The bridge  53  has an AGP (accelerated graphics port)  50 , and is connected to a PCI (peripheral component interconnect/interface) bus  56 . 
     The bridge  53  is implemented by, for example, Intel 400BX which is an AGP host bridge controller manufactured by Intel Corporation, and controls data transmission of the CPU  51 , a RAM (random-access memory)  54  (so-called main memory), and the like. The bridge  53  also controls data transmission to/from a video controller  57  via the AGP  50 . The bridge  53  and a bridge (so-called south bridge (PCI-ISA bridge))  58  construct a so-called chip set. 
     The bridge  53  is also connected to a cache memory  55 . The cache memory  55  is implemented by a memory having the higher-speed write or read capability than the RAM  54  such as an SRAM (static RAM), and caches (temporarily stores) programs or data used by the CPU  51 . 
     The CPU  51  has an internal primary cache memory (which is constructed by a memory operable at a higher speed than the cache memory  55 , and which is controlled by the CPU  51  itself). 
     The RAM  54  is constructed by, for example, a DRAM (dynamic RAM), and stores data necessary for the program executed by the CPU  51  or for operation of the CPU  51 . Specifically, for example, the RAM  54  stores an e-mail program  54 A, an auto pilot program  54 B, a jog dial state monitoring program  54 C, a jog dial driver  54 D, an operating program (OS)  54 E, a content management program  54 F, a browser program  54 G, and other application programs  54 H 1  to  54 Hn, which are loaded from an HDD  67  when a boot-up process is completed. 
     The e-mail program  54 A is a program for exchanging a communication message (so-called electronic mail or e-mail) over a communication line (not shown). 
     The auto pilot program  54 B is a program for sequentially launching a plurality of predetermined processes (or programs) in a predetermined order for processing. 
     The jog dial state monitoring program  54 C receives from each of the above-noted application programs a notice indicating whether or not the application program is compatible with the jog dial  23 , and causes the LCD  26  to display what is done by operating the jog dial  23  when the application program is compatible with the jog dial  23 . 
     The jog dial state monitoring program  54 C detects an event of the jog dial  23  (an operation in which the jog dial  23  is rotated in the direction indicated by the arrow “a” in  FIG. 4  or is pressed in the direction indicated by the arrow “b” in  FIG. 4 ) to execute the process corresponding to the detected event. The jog dial state monitoring program  54 C contains a list of the received notices from the application programs. The jog dial driver  54 D performs various functions according to the operation of the jog dial  23 . 
     The OS (operating system)  54 E is a program for controlling basic operation of a computer, represented by, for example, so-called Windows (registered trademark) Me manufactured by Microsoft Corporation or so-called MacOS (trademark) manufactured by Apple Computer, Inc. 
     The content management program  54 F manages availability including playback, checkout, and check-in of content stored in a content file  67 J recorded in the HDD  67  based on conditions of use stored in a condition-of-use file  67 M. The content management program  54 F sets a checkout period in a user&#39;s area in the conditions of use stored in the condition-of-use file  67 M according to the operation of the keyboard  24  or the touch pad  25 . 
     When a checkout of content is requested from another personal computer, the content management program  54 F checks out the content to this personal computer over the network  4 . 
     When receiving content that is checked out from another personal computer, the content management program  54 F supplies the checked out content to the portable device  2  via a USB port  107 . 
     The browser program  54 G causes the LCD  26  to display an image, a character, or the like based on data supplied from the server  5  over the network  4 , and causes a speaker  65  to plays back a sound. According to operation of the keyboard  24  or the touch pad  25 , the browser program  54 G transmits to the server  5  over the network  4  data indicating the details of the content in which the checkout period is set, content ID of the content in which the checkout period is set, and data indicating the location in which the content in which the checkout period is set is stored. 
     The video controller  57  is connected to the bridge  53  via the AGP  50 , and receives data (image data, text data, or the like) supplied from the CPU  51  via the AGP  50  and the bridge  53  to generate image data corresponding to the received data or to store the received data in an internal video memory without modified. The video controller  57  causes the LCD  26  of the display unit  22  to display an image corresponding to the image data stored in the video memory. 
     A sound controller  64  is connected to the PCI bus  56 . The sound controller  64  captures a signal corresponding to a sound from the microphone  66  to generate data corresponding to the sound, and outputs the data to the RAM  54 ; or the sound controller  64  drives the speaker  65  so as to cause the speaker  65  to output the sound. 
     A PC card interface  111 , which is connected to the PCI bus  56 , supplies data supplied from an interface card  112  placed in the slot  28  to the CPU  51  or the RAM  54 , and outputs data supplied from the CPU  51  to the interface card  112 . A drive  130  is connected to the PCI bus  56  via the PC card interface  111  and the interface card  112 . 
     The drive  130  reads data recorded in a magnetic disc  121 , optical disc  122 , magneto-optical disc  123 , or semiconductor memory  124  attached thereto, and supplies the read data to the RAM  54  via the PC card interface  111 , the interface card  112 , and the PCI bus  56 . 
     A memory card interface  114 , which is connected to the PCI bus  56 , supplies, for example, content supplied from the memory card  3  placed in the memory card slot  115  to the CPU  51  or the RAM  54 , and outputs, for example, content supplied from the CPU  51  to the memory card  3 . 
     A modem  116  is connected to the PCI bus  56 . The modem  116  transmits predetermined data to the network  4  via a public telephone line  117  and an Internet service provider  118 , and receives predetermined data from the network  4 . 
     The bridge (so-called south bridge)  58  is also connected to the PCI bus  56 . The bridge  58  is implemented by, for example, Intel PIIX4E, and includes an IDE (Integrated Drive Electronics) controller/configuration register  59 , a timer circuit  60 , an IDE interface  61 , a USB (universal serial bus) interface  68 , and so on. The bridge  58  performs various I/O (input/output) controls such as control of devices connected to an IDE bus  62  or devices connected via an ISA/EIO (Industry Standard Architecture/Extended Input Output) bus  63  or an I/O interface  69 . 
     The IDE controller/configuration register  59  is formed of two IDE controllers, i.e., a so-called primary IDE controller and secondary IDE controller, a configuration register, and so on (these components are not shown). 
     The HDD  67  is connected to the primary IDE controller via the IDE bus  62 . When a so-called IDE device (not shown) such as a CD-ROM drive or an HDD is connected to another IDE bus, the connected IDE device is electrically connected to the secondary IDE controller. 
     The HDD  67  records an e-mail program  67 A, an auto pilot program  67 B, a jog dial state monitoring program  67 C, a jog dial driver  67 D, an OS  67 E, a content management program  67 F serving as an application program, a browser program  67 G, a plurality of other application programs  67 H 1  to  67 Hn, and so on. The e-mail program  67 A, auto pilot program  67 B, jog dial state monitoring program  67 C, jog dial driver  67 D, OS  67 E, content management program  67 F, browser program  67 G, application programs  67 H 1  to  67 Hn, etc., recorded in the HDD  67  are sequentially supplied and loaded to the RAM  54  during a boot-up process. 
     The HDD  67  further records the condition-of-use file  67 M containing conditions of use of the content, and the content file  67 J containing the content. 
     The USB interface  68  transmits data or commands to the connected portable device  2  via the USB port  107 , and receives data or commands from the portable device  2  via the USB port  107 . 
     The timer circuit  60  supplies data indicating the current time to the CPU  51  via the PCI bus  56  upon a request from the content management program  67 F. The content management program  67 F is able to grasp the elapsed time and the like based on the data indicating the current time supplied from the timer circuit  60 . 
     The I/O interface  69  is also connected to the ISA/EIO bus  63 . The I/O interface  69  is constructed by an embedded controller, and a ROM  70 , a RAM  71 , and a CPU  72  are connected with one another within the I/O interface  69 . 
     The ROM  70  stores in advance an IEEE1394 interface program  70 A, an LED control program  70 B, a touch pad input monitoring program  70 C, a key input monitoring program  70 D, a wake-up program  70 E, a jog dial state monitoring program  70 F, and so on. 
     The IEEE1394 interface program  70 A transmits and receives data (data stored in a packet) complying with the standard specified in IEEE1394 via the IEEE1394 port  101 . The LED control program  70 B controls lighting of the power lamp PL, the battery lamp BL, the message lamp ML, if necessary, or any other LED lamp. The touch pad input monitoring program  70 C is a program for monitoring an input from the touch pad  6  corresponding to a user operation. 
     The key input monitoring program  70 D is a program for monitoring an input from the keyboard  24  or any other key switch. The wake-up program  70 E is a program for determining whether or not a predetermined time has been reached based on the data indicating the current time supplied from the timer circuit  60  in the bridge  58  and for managing ON/OFF of the chips constructing the personal computer  1  to launch a predetermined process (or program) when the predetermined time has been reached. The jog dial state monitoring program  70 F is a program for always monitoring the state of the jog dial  23  as to whether or not a rotary encoder of the jog dial  23  is rotated or whether or not the jog dial  23  is pressed. 
     The ROM  70  also contains a BIOS (basic input/output system)  70 G. The BIOS  70 G controls data communication (input/output) between the OS or application program and a peripheral device (the touch pad  6 , the keyboard  24 , the HDD  67 , or the like). 
     The RAM  71  includes registers  71 A through  71 F which represent an LED control register, a touch pad input status register, a key input status register, a time setting register, an I/O register for the purpose of jog dial state monitoring, and an IEEE1394 I/F register. For example, when the jog dial  23  is pressed to launch the e-mail program  54 A, the LED control register stores a predetermined value so as to control the message lamp ML to light according to the stored value. When the jog dial  23  is pressed, the key input status register stores a predetermined operation key flag. The time setting register sets a predetermined time according to a user operation using the keyboard  24  or the like. 
     The jog dial  23 , the touch pad  6 , the keyboard  24 , the IEEE1394 port  101 , and the like are connected to the I/O interface  69  via a connector (not shown), and the I/O interface  69  outputs a signal corresponding to the operation of the jog dial  23 , the touch pad  6 , or the keyboard  24  to the ISA/EIO bus  63 . The I/O interface  69  also controls data transmission/reception to/from a device connected thereto via the IEEE1394 port  101 . Also connected to the I/O interface  69  are the power lamp PL, the battery lamp BL, the message lamp ML, a power control circuit  73 , and the other LED lamps. 
     The power control circuit  73 , which is connected to an internal battery  74  or an AC power source, supplies necessary power to each block, and performs control for charging the internal battery  74  or a second battery of the peripheral device. The I/O interface  69  further monitors a power switch  27  operated when the personal computer  1  is powered on or off. 
     The I/O interface  69  executes the IEEE1394 interface program  70 A till the jog dial state monitoring program  70 F using an internal battery even in the power-off mode. In other words, the IEEE1394 interface program  70 A till the jog dial state monitoring program  70 F are always active. 
     Therefore, even when the power switch  27  is turned off and the CPU  51  does not execute the OS  54 E, the I/O interface  69  enables the jog dial state monitoring program  70 F. This allows the personal computer  1  to activate processing of predetermined software or script file when the jog dial  23  is pressed in the power saving or power-off mode. 
     Accordingly, there is no need for a dedicated key since the jog dial  23  in the personal computer  1  has a programmable power key (PPK) function. 
     The hardware configuration of the server  5  is similar to the hardware configuration of the personal computer  1  shown in  FIG. 6 , and a description thereof is thus omitted. 
     The configuration of the portable device  2  is described below with reference to  FIG. 7 . A power supply circuit  202  converts a power voltage supplied from a dry cell battery  201  into internal electric power of a predetermined voltage, and supplies the power to a CPU  203  to a display unit  216 , so that the overall portable device  2  is driven. 
     When connected to the personal computer  1  via a USB connector  206  over a USB cable C, a USB controller  207  supplies data containing content transferred from the personal computer  1  to the CPU  203  via an internal bus  208 . 
     The data transferred from the personal computer  1  is formed of 64-byte data per packet, and is transferred at a transfer rate of 12 Mbit/sec from the personal computer  1 . 
     The data transferred to the portable device  2  is constructed by a header and content. The header stores content ID, file name, header size, content key, file size, codec ID, file information, and so on. The header further stores playback restriction data necessary for placing limits on playback, start time, end time, count restriction, a playback counter, a checkout period, and so on. The content is encoded with an encoding method such as ATRAC3, and is encrypted. 
     The header size indicates the data length of the header (for example, 33 bytes), and the file size indicates the data length of the content (for example, 33,636,138 bytes). 
     The content key is a key for decoding the encrypted content, and the content key, which is encrypted based on a session key (temporary key) generated during a mutual authentication process between the personal computer  1  and the portable device  2 , is transmitted from the personal computer  1  to the portable device  2 . 
     When the portable device  2  is connected to the USB port  107  of the personal computer  1  over the USB cable C, the portable device  2  and the personal computer  1  perform a mutual authentication process. The mutual authentication process is implemented by, for example, a challenge-response authentication process. In the challenge-response authentication process, a DSP  209  of the portable device  2  performs a decryption (decoding) process. 
     The challenge-response scheme is a scheme in which, for example, a certain value (challenge) generated by the personal computer  1  is responded by a value (response) generated by the portable device  2  using a secret key shared with the personal computer  1 . In the challenge-response mutual authentication process, since the value generated by the personal computer  1  changes each time the authentication process is performed, for example, even if the value output by the portable device  2  and generated using the secret key is read by an attacker, i.e., so-called “posing” occurs, the value used in the next mutual authentication process differs, thus enabling the personal computer  1  to detect incorrectness. 
     The content ID is an ID corresponding to the content for identifying the content. 
     The codec ID is an ID compatible with a method by which the content is encoded, and, for example, codec ID“1” is compatible with ATRAC3 and codec ID“0” is compatible with MP3 (MPEG (Moving Picture Experts Group) Audio Layer-3). 
     The file name is data in ASCII (American National Standard Code for Information Interchange) code into which a content file corresponding to the content and recorded in the personal computer  1  is converted. The file information is data in ASCII code into which the title of a song, the name of the artist, the name of the lyric writer, the name of the composer, or the like corresponding to the content is converted. 
     The playback restriction data is data indicating whether or not a playback-allowed period during which the content can be played back (that is, start time or end time) or count restriction (restriction on the number of playbacks) is set. When the count restriction is set, “1” is assigned to the playback restriction data; and when the playback-allowed period is set, “2” is assigned to the playback restriction data. When the count restriction is not set and when the playback-allowed period is not set (when the content is purchased and licensed), “0” is assigned to the playback restriction data. 
     The start time and the end time are data indicating a duration of the playback-allowed period when the playback restriction data is set to “2”. For example, if the start time is set to “00040F” and the end time is set to “00070F”, the corresponding content can be played back in a period from Apr. 15, 2000 until Jul. 15, 2000. 
     Similarly, when the playback restriction data is set to “1” or “2”, the count restriction indicates a predetermined number of playbacks allowed which is set in advance in correspondence with the content, and the playback counter provides the number of playbacks of the content which is updated by the CPU  203  each time the content is played back. For example, when the count restriction is set to “02”, the number of content playbacks allowed is two; and when the playback counter is set to “01”, the number of content playbacks is one. 
     As an example, if the playback restriction data is set to “2”, the start time set to “00040F”, the end time set to “00070F”, and the count restriction is set to “02”, then, the portable device  2  can play back the corresponding content twice per day in a period from Apr. 15, 2000 until Jul. 15, 2000. 
     As another example, if the playback restriction data is set to “1”, the start time set to “000000”, the end time set to “000000”, the count restriction set to “0a”, and the playback counter is set to “05”, then, the corresponding content has no limit on the playback-allowed period, ten playbacks allowed, and five playback counts. 
     For example, if checkout period data is set to “00070F”, the portable device  2  is authorized to play back the corresponding content until Jul. 15, 2000, and erases the corresponding content when Jul. 15, 2000 has passed based on data indicating the current time and date supplied from a real-time clock  218 . 
     When the portable device  2  receives content and a content write command from the personal computer  1 , the CPU  203  which executes a main program read from the ROM  205  to the RAM  204  receives the write command, and controls the memory card driver  210  to write the content received from the personal computer  1  to the memory card  3  placed therein. 
     When a playback command corresponding to a user pressing operation of a playback/stop button (not shown) is supplied to the CPU  203  via an operation key controller  211 , the CPU  203  causes the memory card driver  210  to read a playback code and the content from the memory card  3  and to transfer the results to the DSP  209 . 
     The DSP  209  performs CRC (cyclic redundancy check) error detection on the content based on the playback code transferred from the memory card  3 , before playing back the content, and supplies the played back data (indicated by D 1  in  FIG. 7 ) to a digital-to-analog conversion circuit  212 . 
     The DSP  209 , which is integrated with an internal oscillation circuit (not shown), plays back the content based on a master clock MCLK from an externally attached crystal oscillator  209 A, and supplies to the digital-to-analog conversion circuit  212  the master clock MCLK, a predetermined frequency bit clock BCLK generated by the internal oscillation circuit based on the master clock MCLK, and an operation clock LRCLK consisting of frame-based L-channel clock LCLK and R-channel clock RCLK. 
     When the content is played back, the DSP  209  supplies the above-noted operation clock to the digital-to-analog conversion circuit  212  according to the playback code; and when the content is not played back, the DSP  209  stops supplying the operation clock according to the playback code so as to make the digital-to-analog conversion circuit  212  inoperable, thereby reducing the total power consumption of the portable device  2 . 
     Similarly, the CPU  203  and the USB controller  207  have crystal oscillators  203 A and  207 A externally attached thereto, respectively, and execute predetermined processing based on master clock MCLK supplied from the oscillators  203 A and  207 A, respectively. 
     With this structure, the portable device  2  does not require a clock generation module for supplying clocks to circuit blocks such as the CPU  203 , the DSP  209 , and the USB controller  207 , thus providing a simple circuit structure, and can be compact. 
     The digital-to-analog conversion circuit  212  converts the played back content into an analog audio signal, and supplies the signal to an amplifier circuit  213 . The amplifier circuit  213  amplifies the audio signal, and supplies the resulting signal to a headphone (not shown) via a headphone jack  214 . 
     In this way, the portable device  2  plays back content stored in the memory card  3  under control of the CPU  203  when a playback/stop button (not shown) is pressed, and stops a playback of the content when the playback/stop button is pressed during the playback process. 
     When the playback/stop button is pressed after stopping a playback, the portable device  2  resumes a playback of the content at the position at which the previous playback was stopped under control of the CPU  203 . As several seconds has passed without application of any operation since depression of the playback/stop button caused a playback to be stopped, the portable device  2  is automatically powered off to reduce the power consumption. 
     If the playback/stop button is pressed after the portable device  2  is powered off, the portable device  2  does not play back the content at the position at which the previous playback was stopped, but plays back the content from the first song. 
     The CPU  203  of the portable device  2  controls an LCD controller  215  to cause the display unit  216  to display information indicating the state of a playback mode (for example, repeat playback, intro playback, etc.), equalizer adjustment (that is, adjustment of gain corresponding to the frequency band of the audio signal), song number, playing time, a playback, stop, fast forward, or fast rewind mode, a sound volume, the remaining battery life of the dry cell battery  201 , and so on. 
     The portable device  2  further stores into an EEPROM  217  a so-called FAT (file allocation table) which lists the number of contents written in the memory card  3 , the position of blocks in the memory card  3  in which the contents are written, and other various memory storage information, in addition to the ID of the memory card  3 . 
     When connected to the personal computer  1  over the USB cable C (hereinafter referred to as “USB connected”), the portable device  2  recognizes that the portable device  2  is USB connected based on an interrupt signal supplied from the USB controller  207  to the CPU  203 . 
     When recognizing that the portable device  2  is USB connected, the portable device  2  receives an external power supply of a specified current value from the personal computer  1  over the USB cable C, and controls the power supply circuit  202  to stop a power supply from the dry cell battery  201 . 
     When the portable device  2  is USB connected, the CPU  203  causes the DSP  209  to stop playing back the content. Thus, the CPU  203  prevents the external power supplied from the personal computer  1  from exceeding the specified current value, and controls so that the external power of the specified current value can constantly be received. 
     As discussed above, since the CPU  203  allows the power supplied from the dry cell battery  201  to be switched to the power supplied from the personal computer  1  when the portable device  2  is USB connected, the external power from the personal computer  1  which is economical can be used to reduce the power consumption of the dry cell battery  201  which supplies uneconomical power, thereby enabling the battery life of the dry cell battery  201  to be prolonged. 
     The real time clock  218  supplies data indicating the current time and date to the CPU  203 . 
       FIG. 8  illustrates the configuration of the memory card  3 . The memory card  3  is formed by incorporating a flash memory (non-volatile memory)  302 , a memory control block  301 , and a security block  312  including a DES encryption circuit into an IC on a chip. 
     A bi-directional serial interface between the memory card driver  210  of the portable device  2  and the memory card  3  is formed of ten lines. The main four lines are a clock line SCK for transmitting a clock during data transmission, a status line SBS for transmitting the status, a data line DIO for transmitting data, and an interrupt line INT. In addition, two GND lines and two VCC lines serve as power supply lines. The remaining two lines Reserv are undefined lines. 
     The clock line SCK is a line for transmitting a clock synchronous with data. The status line SBS is a line for transmitting a signal indicating the status of the memory card  3 . The data line DIO is a line for inputting and outputting commands and encrypted content. The interrupt line INT is a line for transmitting an interrupt signal indicating an interrupt request from the memory card  3  to the memory card driver  210 . When the memory card  3  is inserted, the interrupt signal is produced. In this embodiment, however, since the interrupt signal is transmitted via the data line DIO, the interrupt line INT is grounded. 
     A serial-to-parallel conversion/parallel-to-serial conversion/interface block (S/P, P/S &amp; IF block for short)  303  of the control block  301  is an interface between the memory card driver  210  connected via the above-noted lines and the control block  301 . The S/P, P/S &amp; IF block  303  converts serial data received from the memory card driver  210  into parallel data to capture the converted data in the control block  301 , and converts parallel data from the control block  301  into serial data to send the converted data to the memory card driver  210 . When receiving commands and data transmitted via the data line DIO, the S/P, P/S &amp; IF block  303  separates it into commands and data for normal access to the flash memory  302 , and commands and data necessary for encryption. 
     In the format in which a command and data are transmitted via the data line DIO, the command is first transmitted, and the data is then transmitted. The S/P, P/S &amp; IF block  303  identifies a command and data necessary for normal access from a command and data necessary for encryption based on code of the received command. Based on the identification result, the command necessary for normal access is stored in a command register  304 , and the data necessary for normal access is stored in a page buffer  305  and a write register  306 . An error correction coding circuit  307  is provided in association with the write register  306 . With respect to the data temporarily stored in the page buffer  305 , the error correction coding circuit  307  generates a redundant code of an error correction code. 
     The output data of the command register  304 , the pager buffer  305 , the write register  306 , and the error correction coding circuit  307  are supplied to a flash memory interface and sequence (memory I/F &amp; sequencer for short)  311 . The memory IF &amp; sequencer  311  is an interface between the control block  301  and the flash memory  302 , and controls data communication therebetween. The data is written to the flash memory  302  via the memory IF &amp; sequencer  311 . 
     The content (content compressed using ATRAC3, also hereinafter referred to as “ATRAC3 data”) written to the flash memory  302  is content encrypted in advance by the personal computer  1  or encrypted by the security block  312  of the memory card  3  for copyright protection. 
     The security block  312  includes a buffer memory  313 , a DES encryption circuit  314 , and a non-volatile memory  315 . 
     The security block  312  of the memory card  3  has a plurality of authentication keys and a storage key unique to each memory card. The non-volatile memory  315 , which stores keys necessary for encryption, is not viewed from the outside. For example, the storage keys are stored in the non-volatile memory  315 . A random number generation circuit is further provided for verification with the memory card driver  210  which is specified (i.e., in the same system in which a particular data format etc. are used) to share a session key. Furthermore, in the DES encryption circuit  314 , the storage key can be used to perform encryption again. 
     Authentication is performed, for example, when the memory card  3  is inserted into the portable device  2 . Authentication is performed by the DSP  209  of the portable device  2  and the security block  312  of the memory card  3 . The portable device  2  verifies the identity of the inserted memory card  3  (the memory card in the same system) and the memory card  3  verifies the identity of the portable device  2  (the memory card driver  210  in the same system), thereby performing authentication. When authentication is performed, each of the portable device  2  and the memory card  3  generates a session key, and shares the session keys. The session keys are generated each time authentication is performed. 
     When content is written to the memory card  3 , the portable device  2  encrypts a content key using the session key, and passes it to the memory card  3 . The memory card  3  decodes the content key using the session key to encrypt the content key using a storage key, and passes it to the portable device  2 . The storage key is a key unique to each memory card  3 , and the portable device  2  causes the encrypted content key and encrypted content to be written to the memory card  3 . 
     The data read from the flash memory  302  is supplied to the page buffer  305 , a read register  308 , and an error correction circuit  309  via the memory IF &amp; sequencer  311 . The data stored in the page buffer  305  is error corrected by the error correction circuit  309 . The error-corrected output of the page buffer  305  and the output of the read register  308  are supplied to the S/P, P/S &amp; IF block  303 , and are supplied to the memory card driver  210  of the portable device  2  via the above-described serial interface. 
     During the reading process, the content key encrypted using the storage key and the content encrypted using a block key are read from the flash memory  302 . The content key is decoded by the security block  312  using the storage key. The decoded content key is encrypted using the session key, and is then transmitted to the memory card driver  210  of the portable device  2 . The portable device  2  decodes the content key using the received session key. The portable device  2  generates a block key using the decoded content key. The block key is used to sequentially decode the encrypted ATRAC3 data. 
     Reference numeral  310  denotes a configuration ROM for storing version information of the memory card  3 , various attribute information, and so on. The memory card  3  is further provided with an erroneous-erase-preventing switch  320  which can be operated by a user, if necessary. When the switch  320  is in the erase-prohibited connection mode, erase of the flash memory  302  is prohibited even if a command for erasing the flash memory  302  is sent from the portable device  2 . Reference numeral  321  denotes an oscillator for generating a reference clock for a timing of the processing of the memory card  3 . 
       FIG. 9  is a diagram showing the functional structure of the server  5 . Upon a request from the personal computer  1 , a web server  351  transmits data indicating the details of content and the like to the personal computer  1  over the network  4 , and receives a user ID and the like transmitted from the personal computer  1  over the network  4 . 
     When receiving a user ID, data necessary for registration, a content request, or the like from the personal computer  1 , the web server  351  supplies the user ID, the data necessary for registration, the content request, or the like to a management server  352 . 
     The management server  352  includes a content management database  361  and a user database  362 . The content management database  361  records data indicating the details of content including the title of a song, the title of an album, and the name of an artist, a checkout period, and so on in correspondence with the content ID. 
     The management server  352  reads the data indicating the details of content, the checkout period, and the like from the content management database  361  upon a request from the web server  351 , and supplies the read data indicating the details of content, checkout period, and the like to the web server  351 . 
     When registration of a user is requested from the web server  351 , the management server  352  generates a user ID for the user to record the user ID in the user database  362 . 
     The user database  362  records credit card number, history of previous billing charges, and so on in correspondence with the user ID which is data for identifying a registered user. 
     When confirmation of registration of a user is requested from the web server  351 , the management server  352  determines whether or not the user ID corresponding to the user has been recorded in the user database  362 . If it is determined that the user ID has been recorded, data indicating that the user has been registered is supplied to the web server  351 ; and if it is determined that the user ID has not been recorded, data indicating that the user has not been registered is supplied to the web server  351 . 
       FIG. 10  is a view showing an exemplary screen displayed by the personal computer  1 - 2  when setting a checkout period in content. The content management program  54 F causes the LCD  26  to display a window including a field  381  onto which an icon corresponding to a content is dragged and dropped to choose the content, and a text box  382  for entering a checkout limit set in the selected content. 
     When an icon corresponding to content is dragged and dropped onto the field  381 , the content management program  54 F selects the content corresponding to the icon. 
     The content management program  54 F causes a checkout limit such as date or a period from the time when a checkout was performed to be entered in the text box  382  while the content is selected, and sets the checkout limit in the conditions of use stored in the condition-of-use file  67 M corresponding to the selected content when a button indicating “REGISTER” is clicked. 
     When song information, a comment, or the like is input, the content management program  54 F sets the song information, comment, or the like in the content. 
       FIG. 11  is a view showing exemplary conditions of use stored in the condition-of-use file  67 M. Content ID is data for identifying each of the contents stored in the content files  67 J. One of values “YES” and “NO” is set in a “checkout allowed” column. If “YES” is set, the content management program  54 F can check out the content specified by the content ID to the portable device  2  or another personal computer  1 . If “NO” is set in the “checkout allowed” column, the content management program  54 F does not check out the content specified by the content ID to the portable device  2  and another personal computer  1 . 
     The maximum number of checkouts which can be performed on the corresponding content file  67 J by the content management program  54 F is set in a “maximum number of checkouts allowed” column. The maximum number of checkouts allowed is not modified. 
     The number of checkouts which can be performed on any of the corresponding content files  67 J by the content management program  54 F at the present time is set in a “number of checkouts allowed” column. When the content management program  54 F executes one checkout, the number of checkouts allowed decrements. When the content management program  54 F executes one check-in, the number of checkouts allowed increments. 
     If none of the content files  67 J is checked out, the same number as the maximum number of checkouts allowed is set in the corresponding “number of checkouts allowed” column. 
     When a checkout is performed to change the number of checkouts allowed from “1” to “0”, “NO” is set in the “checkout allowed” column. When a check-in is performed to change the number of checkouts allowed changes from “0” to “1”, “YES” is set in the “checkout allowed” column. 
     One of values “YES” and “NO” is set in a “move allowed” column. If “YES” is set, the content management program  54 F can move the content specified by the content ID. If “NO” is set in the “move allowed” column, the content management program  54 F does not move the content specified by the content ID. 
     One of values “YES” and “NO” is set in a “copy allowed” column. If “YES” is set, the content management program  54 F can copy the content specified by the content ID. If “NO” is set in the “copy allowed” column, the content management program  54 F does not copy the content specified by the content ID. 
     The number of copies which can be performed by the content management program  54 F is set in a “number of copies allowed” column. 
     A period in which the content specified by the content ID is available (can be checked out, played back, or the like) is described in an “available period” column. 
     An area (for example, Japan or worldwide) in which the content specified by the content ID is available (can be checked out, played back, or the like) is described in an “available area” column. 
     A “signature” column contains signature data based on the data set in the “content ID” column till the “available area” column. The signature data is used to detect alteration of the conditions of use. Since an algorithm for generating the signature data is expressed by unidirectional function and is not publicly open, it is difficult for people other than a provider of the content management program  54 F to generate correct signature data based on the data set in the “content ID” column till the “available area” column. 
     A checkout period is stored in a user&#39;s area in the conditions of use. 
     The content management program  54 F determines whether or not the checkout period corresponding to the checked out content has passed. If it is determined that the checkout period has passed, the number of checkouts allowed increments similarly to when one check-in is performed. 
     When content is checked out, the content and the checkout period thereof are supplied to the portable device  2 . The portable device  2  stores the content and the checkout period into the memory card  3 . 
     The portable device  2  determines whether or not the checkout period stored in the user&#39;s area in the conditions of use corresponding to the content has passed. If it is determined that the checkout period has passed, the portable device  2  erases the corresponding content. 
     A process for registering a user of the personal computer  1 - 1  or the personal computer  1 - 2  which is executed by the personal computer  1 - 1  or the personal computer  1 - 2 , and the server  5  is described below with reference to the flowchart shown in  FIG. 12 . 
     In step S 1001 , the browser program  54 G of the personal computer  1  establishes a connection with the server  5  over the network  4 . 
     In step S 2001 , the web server  351  of the server  5  establishes a connection with the personal computer  1  over the network  4 . 
     In step S 1002 , the browser program  54 G transmits information such as the name, address, or e-mail address of the user, a credit card number, and so on to the server  5  over the network  4 . 
     In step S 2002 , the web server  351  receives the information such as the name, address, or e-mail address of the user, the credit card number, and so on transmitted from the personal computer  1 . The web server  351  supplies the received information such as the name, address, or e-mail address of the user, credit card number, and so on to the management server  352 . 
     In step S 2003 , the management server  352  of the server  5  generates a user ID for the user. In step S 2004 , the management server  352  verifies the validity of the credit card number to record to the user database  362  the generated user ID, the user information, the credit card number, and the like. The management server  352  supplies the generated user ID to the web server  351 . 
     In step S 2005 , the web server  351  transmits the user ID to the personal computer  1  over the network  4 . 
     In step S 1003 , the browser program  54 G of the personal computer  1  receives the user ID. The browser program  54 G records the received user ID to the JDD  67  or displays it on the LCD  26 , and is disconnected from the server  5 . Then, the process ends. 
     As discussed above, the personal computer  1  and the server  5  are able to register a user of the personal computer  1 . The registration process allows the server  5  to record a credit card number in correspondence with the user ID. Thus, when the user ID and service are requested from the personal computer  1 , the server  5  can charge the user of the personal computer  1  based on the corresponding credit card number. 
     A process for recording information relevant to content in which a checkout period is set which is executed by the personal computer  1 - 2  and the server  5  is described below with reference to the flowchart shown in  FIG. 13 . In step S 1101 , the content management program  54 F of the personal computer  1 - 2  sets a checkout period in the conditions of use corresponding to content based on data entered using the screen shown in  FIG. 10 . In step S 1102 , the browser program  54 G of the personal computer  1 - 2  is connected with the server  5  over the network  4 . 
     In step S 2101 , the web server  351  is connected with the personal computer  1 - 2  over the network  4 . 
     In step S 1103 , the browser program  54 G transmits a user ID to the server  5  over the network  4 . The user ID to be transmitted is stored in advance in the personal computer  1 - 2  or is entered to the personal computer  1 - 2  by operating the keyboard  24  or the like. 
     In step S 2102 , the web server  351  receives the user ID transmitted by the personal computer  1 - 2 . The web server  351  inquires of the management server  352  whether or not the received user ID has been registered in the user database  362 . In step S 2103 , the management server  352  checks whether or not the user ID has been registered in the user database  362 . If it is determined that the user ID has been registered in the user database  362 , the user ID is authorized, and the process proceeds to the subsequent step. If it is determined that the user ID has not been registered in the user database  362 , the user ID is not authorized, and the process ends without performing the subsequent processing. 
     In step S 1104 , the browser program  54 G transmits to the server  5  over the network  4  content ID, the details of content, a checkout period, and data indicating the location in which the content is recorded. 
     In step S 2104 , the web server  351  receives the content ID, the details of content, the checkout period, and the data indicating the location in which the content is recorded, which are transmitted by the personal computer  1 - 2 . The web server  351  supplies to the management server  352  the content ID, the details of content, the checkout period, and the data indicating the location in which the content is recorded. 
     In step S 2105 , the management server  352  records to the content management database  361  the content ID, the details of content, the checkout period, and the data indicating the location in which the content is recorded, and the process ends. 
     As discussed above, the server  5  is able to record, in correspondence with content ID, the details of content, a checkout period, and data indicating the location in which the content is recorded. 
     The server  5  may perform a billing process for charging a bill to the user of the personal computer  1 - 2  when the details of content, a checkout period, and data indicating the location in which the content is recorded are recorded in correspondence with content ID. 
     The server  5  may further add points to the user database  362  corresponding to the user ID of the user of the personal computer  1 - 2  when the details of content, a checkout period, and data indicating the location in which the content is recorded are recorded in correspondence with content ID. For example, the user of the personal computer  1 - 2  can obtain goods in exchange of the points, or can obtain information on contents of a personal computer in exchange of the points. 
     A content checkout process executed by the personal computer  1 - 1  is described below with reference to the flowchart shown in  FIG. 14 . In step S 3201 , the browser program  54 G of the personal computer  1 - 1  is connected with the server  5  over the network  4 . 
     In step S 2202 /S 2201 , the webs server  351  is connected with the personal computer  1 - 1  over the network  4 . 
     In step S 3202 , the browser program  54 G transmits a user ID to the server  5  over the network  4 . 
     In step S 2202 , the web server  351  receives the user ID transmitted by the personal computer  1 - 1 . The web server  351  inquires of the management server  352  whether or not the received user ID has been registered in the user database  362 . In step S 2203 , the management server  352  checks whether or not the user ID has been registered in the user database  362 . If it is determined that the user ID has been registered in the user database  362 , the process proceeds to the subsequent step. If it is determined that the user ID has not been registered in the user database  362 , the process ends. 
     In step S 3203 , the browser program  54 G issues a content information request to the server  5  over the network  4 . 
     Before a user verification process based on the user ID or in place of a user verification process based on the user ID, the personal computer  1 - 1  and the server  5  may perform a mutual authentication process. 
     In step S 2204 , the web server  351  reads content ID, the details of content, a checkout period, and data indicating the location in which the content is recorded from the content management server  361  via the management server  352 , and supplies to the personal computer  1 - 1  over the network  4  the content ID, the details of content, the checkout period, and the data indicating the location in which the content is recorded. In step S 2205 , the management server  352  charges a bill for the provided content information based on the user data recorded in the user database  362 . For example, the management server  352  charges a bill based on a user&#39;s credit card number recorded in the user database  362  in correspondence with the user ID. 
     In the billing process, for example, a bill for the provided content information may be charged per month. 
     In step S 3204 , the personal computer  1 - 1  receives the content ID, the details of content, the checkout period, and the data indicating the location in which the content is recorded, which are transmitted by the server  5 . 
     In step S 3205 , the personal computer  1 - 1  issues a content checkout request to the personal computer  1 - 2  over the network  4  based on the content ID and the data indicating the location in which the content is recorded. 
     In step S 1201 , the personal computer  1 - 2  checks out the content corresponding to the content ID over the network  4  according to the request from the personal computer  1 - 1 . 
     In step S 4201 , the portable device  2  receives the content transmitted by the personal computer  1 - 2  via the personal computer  1 - 1  over the network  4 . In step S 4202 , the portable device  2  stores the content into the memory card  3  placed therein, and the process ends. 
     As discussed above, the personal computer  1 - 1  is able to obtain information on content in which a checkout period is set from the server  5  to cause the personal computer  1 - 2  to check out the content, and to store the content into the memory card  3 . 
     The server  5  is able to charge a user of the personal computer  1 - 1  for the content information provided for the personal computer  1 - 1 . 
     The personal computer  1 - 1  may record the content checked out from the personal computer  1 - 2 , and may move the recorded content to the memory card  3 . 
     An automatic check-in process for content executed by the portable device  2  is described below with reference to the flowchart shown in  FIG. 15 . 
     In step S 11 , the portable device  2  determines whether or not a playback of content is requested. If it is determined that a playback of content is requested, the process proceeds to step S 12 , in which it is determined whether or not the checkout period of the content has passed based on the current time and date supplied from the real-time clock  218 . 
     If it is determined in step S 12  that the checkout period of the content has passed, the process proceeds to step S 13 , in which the portable device  2  erases the content stored in the memory card  3  together with the data corresponding to the content. 
     If it is determined in step S 11  that a playback of content is not requested, the process ends. 
     If it is determined in step S 12  that the checkout period of the content has not passed, there is no need for check-in, and the process ends. 
     As discussed above, the portable device  2  is able to automatically check in the content stored in the memory card  3 . 
     The portable device  2  may perform processing of steps S 12  and S 13  at a predetermined interval such as every day. 
     An automatic check-in process executed by the personal computer  1 - 2  is described below with reference to the flowchart shown in  FIG. 16 . 
     In step S 21 , the content management program  54 F determines whether or not the checkout period of the content has passed based on the current time and date supplied from the timer circuit  60 . If it is determined that the checkout period of the content has passed, the process proceeds to step S 22 , in which the number of checkouts allowed in the conditions of use stored in the condition-of-use file  67 M corresponding to the content increments by one. Then, the process ends. 
     If it is determined in step S 21  that the checkout period of the content has not passed, there is no need for check-in, and the process ends. 
     As discussed above, the personal computer  1 - 2  is able to automatically check in content. 
       FIG. 17  is a configuration diagram showing another embodiment of the content providing system. Portions similar to those shown in  FIG. 1  are designated by the same reference numerals, and a description thereof is omitted. 
     A portable device  401  includes an internal storage medium such as a flash memory, and stores content checked out from the personal computer  1 - 2  into the internal storage medium. 
     The portable device  401  erases the stored content when the checkout period set in the conditions of use corresponding to the stored content has passed. 
       FIG. 18  is an illustration of the configuration of the portable device  401 . Portions similar to those shown in  FIG. 7  are designated by the same reference numerals, and a description thereof is omitted. 
     When the portable device  401  receives content and a write command of the content from the personal computer  1 , the CPU  203  which executes a main program read from the ROM  204  to the RAM  205  receives the write command, and controls a flash memory control  421  to write the content received from the personal computer  1  to a flash memory  422 . 
     The flash memory  422  has a storage capacity of about 64 Mbytes, and stores content. The flash memory  422  also stores in advance a playback code for decompressing content compressed with a predetermined compression method. 
     When a playback command corresponding to a user pressing operation of a playback/stop button (not shown) is supplied to the CPU  203  via the operation key controller  211 , the CPU  203  causes the flash memory controller  421  to read the playback code and the content from the flash memory  422  and to transfer the results to the DSP  209 . 
     The DSP  209  performs CRC error detection on the content based on the playback code transferred from the flash memory  422 , before playing back the content, and supplies the played back data to the digital-to-analog conversion circuit  212 . 
     The user registration, content registration, content checkout, and automatic content check-in processes of the content providing system shown in  FIG. 17  are similar to those of the content providing system shown in  FIG. 1 , and a description thereof is thus omitted. 
       FIG. 19  is a configuration diagram showing still another embodiment of the content providing system. 
     A camera-equipped digital cellular telephone set  501  is configured so that a memory card  3  is attachable thereto, and stores content checked out from the personal computer  1 - 2  into the attached memory card  3 . 
     The camera-equipped digital cellular telephone set  501  erases the content stored in the memory card  3  when the checkout period set in the conditions of use corresponding to the stored content has passed. 
     The appearance of the camera-equipped digital cellular telephone set  501  constructing the content providing system according to the present invention is described below. As shown in  FIG. 20 , the camera-equipped digital cellular telephone set  501  is formed of a display unit  521  and a body  522  so as to be foldable by a central hinge portion  523 . 
     A transmission/reception antenna  524  extendable or receivable is provided on the top left portion of the display unit  521 . The camera-equipped digital cellular telephone set  501  transmits and receives radio waves to and from a base station which is a fixed radio station via the antenna  524 . 
     A camera  525  which is rotatable in an angular range of about 180° is provided on the top center portion of the display unit  521 . The camera-equipped digital cellular telephone set  501  uses a CCD (charge-coupled device) camera  526  of the camera  525  to capture an image of a desired object. 
     When the camera  525  is rotated approximately 180° and is positioned by a user, as shown in  FIG. 21 , the display unit  521  is in the state in which a speaker  527  disposed at the center of the rear surface of the camera  525  is positioned on the front side. Then, the camera-equipped digital cellular telephone set  501  is switched to a normal talk mode. 
     A liquid crystal display  528  is disposed on the front surface of the display unit  521 . The liquid crystal display  528  displays the reception status, the remaining battery life, the name or telephone number of other parties registered in a telephone directory, call history, an e-mail message, a simple home page, an image captured by the CCD camera  526  of the camera  525  or a map image indicating a route, and so on. 
     Meanwhile, the body  522  has operation keys  529  mounted on a surface thereof, including number keys “0” to “9”, a dial key, a re-dial key, an end/power key, a clear key, and an e-mail key. Various commands corresponding to the operation of the operation keys  529  are input to the camera-equipped digital cellular telephone set  501 . 
     The body  522  is further provided with a memo button  530  and a microphone  531  below the operation keys  529 . When the memo button  530  is operated, the camera-equipped digital cellular telephone set  501  records voice of the other party of call in-progress. The camera-equipped digital cellular telephone set  501  uses the microphone  531  to collect voice of the user when talking. 
     The body  522  is further provided with a rotatable jog dial  532  above the operation keys  529  so that the jog dial  532  is slightly projected from the surface of the body  522 . As the jog dial  532  is rotated, the camera-equipped digital cellular telephone set  501  performs various operations, such as scrolls through a telephone directory or an e-mail displayed on the liquid crystal display  528 , scrolls through a simple home page, and scrolls through an image. 
     For example, as the jog dial  532  is rotated by the user, the body  522  selects a desired telephone number from a plurality of telephone numbers in a telephone directory displayed on the liquid crystal display  528 . When the jog dial  532  is pressed in the body  522 , the selected telephone number is determined, and the determined telephone number is automatically dialed. 
     A battery pack (not shown) is attached to the rear side of the body  522 . When the end/power key is turned on, power is supplied from the battery pack to each circuit to make it active. 
     A memory card slot  533  for receiving a memory card  3  attachable and detachable thereto and therefrom is provided at the upper portion on the left side surface of the body  522 . 
     When the memo button  530  is pressed, the camera-equipped digital cellular telephone set  501  records voice of the other party of call in-progress to the memory card  3 . The camera-equipped digital cellular telephone set  501  records an e-mail, a simple home page, or an image captured by the CCD camera  526  to the received memory card  3  according to the operation of the user. 
     The memory card  3  is implemented by, for example, a memory stick (trademark), which is a flash memory card, developed by the present applicant, Sony Corporation. This memory card  3  is designed so that a flash memory device which is an EEPROM (electrically erasable and programmable read only memory) serving as an electrically writable or erasable non-volatile memory is received in a compact thin plastic case of 21.5 mm×50 mm×2.8 mm, and the memory card  3  is capable of writing and reading various data such as image, audio, and music data via a 10-pin terminal. 
     In order to support the specification modification of the internal flash memory aiming at large capacity etc., the memory card  3  employs an independent serial protocol which provides the compatibility with a device used, thereby achieving high speed performance of the maximum write speed of 1.5 MB/S and the maximum read speed of 2.45 MB/S. The memory card  3  further includes an erroneous-erase-preventing switch to achieve high reliability. 
     Therefore, the camera-equipped digital cellular telephone set  501  is designed so that the memory card  3  is attachable thereto, and is able to share data with another electronic device such as the personal computer  1 . 
     As shown in  FIG. 13 , the camera-equipped digital cellular telephone set  501  is configured so that a power supply circuit  552 , an operation input controller  553 , an image encoder  554 , a camera interface  555 , an LCD (liquid crystal display) controller  556 , an image decoder  557 , a multiplexer/demultiplexer  558 , a storage/playback unit  563 , a modulation/demodulation circuit  559 , and an audio codec  560  are mutually connected via a main bus  561  with a main controller  551  for comprehensively controlling the display unit  521  and the body  522 , and the image encoder  554 , the image decoder  557 , the multiplexer/demultiplexer  558 , the modulation/demodulation circuit  559 , and the audio codec  560  are connected with one another via a synchronization bus  562 . 
     When the end/power key is turned on by a user operation, the power supply circuit  552  supplies power to components from a battery pack, thereby making the camera-equipped digital cellular telephone set  501  active. 
     In the talk mode, the camera-equipped digital cellular telephone set  501  converts an audio signal obtained by collecting voice using the microphone  531  into digital audio data by the audio codec  560  under control of the main controller  551  formed of a CPU, a ROM, a RAM, and so on. The camera-equipped digital cellular telephone set  501  spreads the spectrum of the digital audio data in the modulation/demodulation circuit  559 , which is then subjected to digital-to-analog conversion and frequency conversion in the transmission/reception circuit  564 , before transmitting the result via the antenna  524 . 
     In the talk mode, the camera-equipped digital cellular telephone set  501  amplifies a signal received by the antenna  524 , which is then subjected to frequency conversion and analog-to-digital conversion, and despreads the resulting signal in the modulation/demodulation circuit  559 . The resulting signal is converted into an analog audio signal by the audio codec  560 . The camera-equipped digital cellular telephone set  501  outputs a sound corresponding to the analog audio signal from the speaker  527 . 
     When transmitting an e-mail in the data communication mode, the camera-equipped digital cellular telephone set  501  transmits text data of the e-mail entered by the operation of the operation keys  529  and the jog dial  532  to the main controller  551  via the operation input controller  553 . 
     The main controller  551  spreads the spectrum of the text data in the modulation/demodulation circuit  559 , which is then subjected to digital-to-analog conversion and frequency conversion in the transmission/reception circuit  564 , before transmitting the result to the base station via the antenna  524 . 
     When receiving an e-mail in the data communication mode, on the other hand, the camera-equipped digital cellular telephone set  501  despreads the signal received from the base station via the antenna  524  in the modulation/demodulation circuit  559  to recover the original text data, and displays it in the e-mail format on the liquid crystal display  528  via the LCD controller  556 . 
     The main controller  551  executes a mail transmission/reception program when an e-mail is transmitted or received in the data communication mode. 
     Thereafter, the camera-equipped digital cellular telephone set  501  may record the received e-mail to the memory card  3  via the storage/playback unit  563  according to a user operation. 
     When transmitting image data in the data communication mode, the camera-equipped digital cellular telephone set  501  supplies image data captured by the CCD camera  526  to the image encoder  554  via the camera interface  555 . 
     The camera-equipped digital cellular telephone set  501  may also display the image data captured by the CCD camera  526  directly on the liquid crystal display  528  via the camera interface  555  and the LCD controller  556  when the image data is not transmitted. 
     The image encoder  554  compresses and encodes the image data supplied from the CCD camera  526  using a predetermined coding scheme such as MPEG (Moving Picture Experts Group)-2 or MPEG-4 for conversion into encoded image data, and sends it to the multiplexer/demultiplexer  558 . 
     At the same time, the camera-equipped digital cellular telephone set  501  converts voice collected by the microphone  531  when the image is captured by the CCD camera  526  into digital audio data, and sends it to the multiplexer/demultiplexer  558  via the audio codec  560 . 
     The multiplexer/demultiplexer  558  multiplexes the encoded image data supplied from the image encoder  554  and the audio data supplied from the audio codec  560  using a predetermined method, and the resulting multiplexed data is then subjected to spread spectrum in the modulation/demodulation circuit  559  and is subjected to digital-to-analog conversion and frequency conversion in the transmission/reception circuit  564 , before the result is transmitted via the antenna  524 . 
     When receiving moving image file data linked to, for example, a simple home page in the data communication mode, on the other hand, the camera-equipped digital cellular telephone set  501  despreads in the modulation/demodulation circuit  559  the signal received from the base station via the antenna  524 , and sends the resulting multiplexed data to the multiplexer/demultiplexer  558 . 
     The multiplexer/demultiplexer  558  demultiplexes the multiplexed data into encoded image data and audio data, and supplies the encoded image data to the image decoder  557  and the audio data to the audio codec  560  via the synchronization bus  562 . 
     The image decoder  557  decodes the encoded image data using a decoding method corresponding to the predetermined encoding method such as MPEG-2 or MPEG-4 to reproduce moving image data, and supplies the resulting data to the liquid crystal display  528  via the LCD controller  556 . Thus, the camera-equipped digital cellular telephone set  501  displays moving image data contained in a moving image file linked to, for example, a simple home page. 
     At the same time, the audio codec  560  converts the audio data into an analog audio signal, and then supplies it to the speaker  527 . Thus, the camera-equipped digital cellular telephone set  501  plays back audio data contained in a moving image file linked to, for example, a simple home page. 
     In this case, similarly to e-mail cases, the camera-equipped digital cellular telephone set  501  is able to record the received data linked to a simple home page or the like to the memory card  3  via the storage/playback unit  563  according to a user operation. 
     A process for registering a user of the camera-equipped digital cellular telephone set  501  is similar to the process discussed above with reference to the flowchart shown in  FIG. 12 , and a description thereof is thus omitted. 
     A content checkout process is described below with reference to the flowchart shown in  FIG. 23 . 
     In step S 3301 , the camera-equipped digital cellular telephone set  501  is connected with the server  5  over the network  4 . 
     In step S 2301 , the web server  351  is connected with the camera-equipped digital cellular telephone set  501  over the network  4 . 
     In step S 3302 , the camera-equipped digital cellular telephone set  501  transmits a user ID to the server  5  over the network  4 . 
     In step S 2301 , the web server  351  receives the user ID transmitted by the camera-equipped digital cellular telephone set  501 . The web server  351  inquires of the management server  352  whether or not the received user ID (step S 2302 ) has been registered in the user database  362 . In step S 2303 , the management server  352  checks whether or not the user ID has been registered in the user database  362 . If it is determined that the user ID has been registered in the user database  362 , the process proceeds to subsequent steps S 2304 , S 2305 . If it is determined that the user ID has not been registered in the user database  362 , the process ends. 
     In step S 3303 , the camera-equipped digital cellular telephone set  501  issues a content information request to the server  5  over the network  4 . 
     In step S 2304 , the web server  351  reads a checkout period and data indicating the location in which the content is recorded from the content management server  361  via the management server  352 , and supplies to the camera-equipped digital cellular telephone set  501  over the network  4  content ID, the checkout period, and the data indicating the location in which the content is recorded. 
     In step S 3304 , the camera-equipped digital cellular telephone set  501  receives the content ID, the checkout period, and the data indicating the location in which the content is recorded, which are transmitted from the server  5 . 
     In step S 3305 , the camera-equipped digital cellular telephone set  501  issues a content checkout request to the personal computer  1 - 2  based on the content ID and the data indicating the location in which the content is recorded. 
     In step S 1301 , the personal computer  1 - 2  checks out the content according to the request from the camera-equipped digital cellular telephone set  501 . 
     In step S 3306 , the camera-equipped digital cellular telephone set  501  receives the content transmitted by the personal computer  1 - 2  over the network  4 . In step S 3307 , the camera-equipped digital cellular telephone set  501  stores the content in the memory card  3  placed therein, and the process ends. 
     An automatic check-in process of the camera-equipped digital cellular telephone set  501  is similar to the process discussed above with reference to the flowchart shown in  FIG. 15 , and a description thereof is thus omitted. 
     As discussed above, the content providing system shown in  FIG. 19  is able to automatically check in checked out content. 
       FIG. 24  is a configuration diagram showing still another embodiment of the content providing system. Portions similar to those shown in  FIG. 19  are designated by the same reference numerals, and a description thereof is omitted. 
     A camera-equipped digital cellular telephone set  601  has a similar structure to that of the camera-equipped digital cellular telephone set  501  except that the camera-equipped digital cellular telephone set  601  includes an internal storage medium such as a flash memory. 
     The camera-equipped digital cellular telephone set  601  receives content checked out from the personal computer  1 - 2 , and stores the received content into the internal storage medium. 
     The camera-equipped digital cellular telephone set  601  erases the stored content when the checkout period set in the conditions of use corresponding to the stored content has passed. 
     An automatic check-in process of the camera-equipped digital cellular telephone set  601  is similar to the process discussed above with reference to the flowchart shown in  FIG. 15 , and a description thereof is thus omitted. 
       FIG. 25  is a configuration block diagram showing still another embodiment of the content providing system according to the present invention. 
     The camera-equipped digital cellular telephone set  601  sets a checkout period in content recorded therein, and transmits to a server  701  over the network  4  data indicating the details of the content in which the checkout period is set, and content ID of the content in which the checkout period is set. The camera-equipped digital cellular telephone set  601  moves the content in which the checkout period is set to the server  701  over the network  4 . 
     A personal computer  1 - 2  sets a checkout period in content recorded therein, and transmits to the server  701  over the network  4  data indicating the details of the content in which the checkout period is set, and content ID of the content in which the checkout period is set. The personal computer  1 - 2  moves the content in which the checkout period is set to the server  701  over the network  4 . 
     A server  701  records the data indicating the details of the content in which the checkout period is set and the content ID of the content in which the checkout period is set, which are received from the personal computer  1 - 2  or the camera-equipped digital cellular telephone set  601 . The server  701  records the content moved from the personal computer  1 - 2  or the camera-equipped digital cellular telephone set  601 . 
     When data relevant to content is requested from the personal computer  1 - 1 , the server  701  transmits to the personal computer  1 - 1  data indicating the details of content in which a checkout period is set and content ID of content in which a checkout period is set. 
     The personal computer  1 - 1  displays the details of the content in which the checkout period is set based on the data indicating the details of the content in which the checkout period is set. According to the operation of a user who selects content to be checked out based on the displayed details, the personal computer  1 - 1  issues a content checkout request to the server  701  based on the content ID of the content in which the checkout period is set. 
     According to the content checkout request from the personal computer  1 - 1 , the server  701  checks out the content in which the checkout period is set to the memory card  3  over the network  4  via the personal computer  1 - 1  and the portable device  2 . 
     When content in which a checkout period is set is checked out, the server  701  increments the number of checkouts allowed in the conditions of use by one when the checkout period set in the conditions of use corresponding to the checked out content has passed. 
     The personal computer  1 - 1  transmits the checked out content to the portable device  2  connected thereto via USB or the like. The portable device  2  stores the content received from the personal computer  1 - 1  in the memory card placed therein. 
     When the checkout period set in the content has passed, the portable device  2  erases the content in which the checkout period is set and which is stored in the memory card  3 . 
       FIG. 26  is a diagram showing the functional structure of the server  701 . Portions similar to those shown in  FIG. 9  are designated by the same reference numerals, and a description thereof is omitted. 
     A management server  741  includes a content management database  361 , a user database  362 , a content database  751 , and a content use history database  752 . 
     The content database  751  records the content moved from the personal computer  1 - 2  or the camera-equipped digital cellular telephone set  601 . 
     When content is checked out from the content database  751  to the personal computer  1 - 1 , the content use history database  752  records the content ID of the checked out content, the user ID corresponding to a user who requests a checkout, and history including checkout count. 
       FIG. 27  is a view showing an exemplary screen displayed by the personal computer  1 - 2  when setting a checkout period in content and moving the content to the server  701 . The content management program  54 F causes the LCD  26  to display a window including a field  381  onto which an icon corresponding to a content is dragged and dropped to choose the content, and a text box  382  for entering a checkout limit set in the selected content. 
     When an icon corresponding to content is dragged and dropped onto the field  381 , the content management program  54 F selects the content corresponding to the icon. 
     The content management program  54 F causes a checkout limit such as date or a period to be entered in the text box  382  while the content is selected, and sets the checkout limit in the conditions of use corresponding to the selected content when a button indicating “REGISTER” is clicked. 
     When song information, a comment, or the like is input, the content management program  54 F sets the song information, comment, or the like in the content. 
     The content management program  54 F causes the content in which the checkout limit is set to be moved to the server  701  over the network  4 . 
     The browser program  54 G may cause the content in which the checkout limit is set to be moved to the server  701 . 
       FIGS. 28 and 29  show example data recorded in the content use history database  752 . 
     The example shown in  FIG. 28  is data indicating a log of checkout count recorded in the content use history database  752 . The data indicating a log of checkout count records, in correspondence with the content ID, a user ID corresponding to a user who checks out the content, the title of a song, and checkout count of the content. 
     The checkout count may represent the number of checkouts after the content is moved to the server  701 , or may represent the number of checkouts at a predetermined interval, for example, the number of checkouts per week. 
     In the example shown in  FIG. 28 , user ID “aaa”, song “ddd”, and checkout count “jjj” are recorded in correspondence with content ID “AAA”. User ID “bbb”, song “eee”, and checkout count “kkk” are recorded in correspondence with content ID “BBB”. User ID “ccc”, song “fff”, and checkout count “lll” are recorded in correspondence with content ID “CCC”. 
     The example shown in  FIG. 29  is data indicating the details of content recorded in the content use history database  752 . The data indicating the details of content contains the title of an album, the name of an artist, a category, a track number, and so on in correspondence with the title of a song. 
     In the example shown in  FIG. 29 , album “AaA”, artist “DdD”, category “classic”, and track number “2” are recorded in correspondence with song “ddd”. Album “BbB”, artist “EeE”, category “jazz”, and track number “4” are recorded in correspondence with song “eee”. Album “CcC”, artist “FfF”, category “hip-hop”, and track number “6” are recorded in correspondence with song “fff”. 
     Accordingly, the server  701  records the user ID of a user who checks out content, the checkout count of the content, and the details of the content, and can therefore grasp how many checkouts of content of what album in what category was performed. 
     A content moving process performed by the camera-equipped digital cellular telephone set  601  and the server  701  is described below with reference to the flowchart shown in  FIG. 30 . The processing of steps S 1401  through S 2403  is similar to the processing of steps S 1101  through S 2103  in  FIG. 13 , respectively, and a description thereof is thus omitted. 
     In step S 1401 , the camera-equipped digital cellular telephone set  601  transmits to the server  701  data indicating the details of content, the corresponding conditions of use, and the content in which a checkout period is set in order to move the content. 
     In step S 2404 , the web server  351  of the server  701  receives the data indicating the details of the content, the corresponding conditions of use, and the content, which are transmitted by the camera-equipped digital cellular telephone set  601 . The web server  351  supplies the received conditions of use and content to the management server  741 . 
     In step S 2405 , the content management server  741  of the server  701  records the content in which the checkout period is set and the corresponding conditions of use to the content database  751 , and the process ends. 
     As discussed above, the server  701  is able to record content in which a checkout period is set and which is moved. 
     A checkout process of the content processing shown in  FIG. 25  is described below with reference to the flowchart shown in  FIG. 31 . The processing of steps S 3501  through S 3504  is similar to the processing of steps S 3201  through S 3204  in  FIG. 14 , respectively, and a description thereof is thus omitted. 
     In step S 3505 , the browser program  54 G of the personal computer  1 - 1  issues a content checkout request to the server  701  over the network  4 . 
     In Step S 2505 , according to the request from the personal computer  1 - 1 , the server  701  causes the content to be read from the content database  751  of the management server  741 , and causes the web server  351  to check out the content. 
     In step S 2506 , the management server  741  performs a billing process based on the user data recorded in the user database  362 . In step S 2507 , the management server  741  records a log corresponding to the checked out content to the content use history database. 
     In step S 4501 , the portable device  2  receives the checked out content transmitted by the server  701  via the personal computer  1 - 1 . In step S 4502 , the portable device  2  records the checked out content to the memory card  3  attached thereto, and the process ends. 
     As discussed above, the server  701  is able to check out content in which a checkout period is set. 
     An automatic check-in process of the server  701  is similar to the process discussed above with reference to the flowchart shown in  FIG. 16 , and a description thereof is thus omitted. 
       FIG. 32  is a configuration diagram showing still another embodiment of the content providing system according to the present invention. Portions similar to those shown in  FIG. 19  are designated by the same reference numerals, and a description thereof is omitted. 
     A camera-equipped digital cellular telephone set  601 - 2  shown in  FIG. 32 , which corresponds to the camera-equipped digital cellular telephone set  601  shown in  FIG. 19 , moves content in which a checkout period is set to the server  701 . 
     A camera-equipped digital cellular telephone set  601 - 1  checks out the content in which the checkout period is set from the server  701 , and stores the content into an internal storage medium such as a flash memory. 
     The camera-equipped digital cellular telephone set  601 - 1  erases the stored content when the checkout period has passed. 
     A content checkout process performed by the camera-equipped digital cellular telephone set  601 - 1  and the server  701  is described below with reference to the flowchart shown in  FIG. 33 . 
     The processing of steps S 3601  through S 2607  is similar to the processing of steps S 3501  through S 2507  in  FIG. 31 , respectively, except that the processing is executed by the camera-equipped digital cellular telephone set  601 - 1  in place of the personal computer  1 - 1 , and a description thereof is thus omitted. 
     In step S 3606 , the camera-equipped digital cellular telephone set  601 - 1  receives the content checked out by the server  701 . In step S 3607 , the camera-equipped digital cellular telephone set  601 - 1  stores the received content into the internal storage medium, and the process ends. 
     An automatic check-in process of the camera-equipped digital cellular telephone set  601 - 1  is similar to the process discussed above with reference to the flowchart shown in  FIG. 15 , and a description thereof is thus omitted. 
     As discussed above, the content providing system is able to automatically check in content in which a checkout limit is set. 
     The content providing system is further able to charge a bill for the provided information relevant to content in which a checkout limit is set. 
     Although the content is music/sound data in the foregoing description, the content is not limited to music/sound data, and any useful data of still image, moving picture, computer program, or numerical data may be used. 
     In the foregoing description, the personal computer  1 - 1 , the camera-equipped digital cellular telephone set  501 , the camera-equipped digital cellular telephone set  601 , or the camera-equipped digital cellular telephone set  601 - 1  issues a request for content information to the server  5  or the server  701 , and the server  5  or the server  701  provides the content information; however, regardless of the presence or absence of the request from the personal computer  1 - 1 , the camera-equipped digital cellular telephone set  501 , the camera-equipped digital cellular telephone set  601 , or the camera-equipped digital cellular telephone set  601 - 1 , the server  5  or the server  701  may provide the content information in the e-mail format to the personal computer  1 - 1 , the camera-equipped digital cellular telephone set  501 , the camera-equipped digital cellular telephone set  601 , or the camera-equipped digital cellular telephone set  601 - 1 . 
     A dedicated server for recording and providing content in which a checkout limit is set may be provided. 
     The server  5  or the server  701  may provide visual and audio data corresponding to content to the personal computer  1 - 1 , the camera-equipped digital cellular telephone set  501 , the camera-equipped digital cellular telephone set  601 , or the camera-equipped digital cellular telephone set  601 - 1 . 
     The above-described series of processes may be executed by hardware or software. If the series of processes is executed by software, a program constructing the software is installed from a program storage medium to a computer incorporated in dedicated hardware or to device capable of achieving various functions by installing various programs, such as a general-purpose personal computer. 
     A program storage medium for storing a program installed to a computer and executable by the computer is constructed by packaged media such as the magnetic disk  121  (including a floppy disk), optical disk  122  (including a CD-ROM (compact disc-read only memory) and a DVD (digital versatile disc)), magneto-optical disk  123  (including an MD (Mini-Disc)(trademark)), and semiconductor memory  124  shown in  FIG. 6 , or the ROM  701  or HDD  67  having the program stored temporarily or permanently therein. The program is stored into the program storage medium using wired or wireless communication media such as a local area network, the Internet, and digital satellite broadcasting via interfaces such as a router and a modem, if necessary. 
     As is anticipated herein, the steps describing a program recorded in a program storage medium include steps performed in a time-series manner according to the described order, and steps performed in a parallel or discrete manner although the steps are not necessarily performed in a times-series manner. 
     A program executing the above-described series of processes may be installed to a computer via wired or wireless communication media such as a local area network, the Internet, and digital satellite broadcasting via interfaces such as a router and a modem, if necessary. 
     As used herein, a system represents an overall apparatus constructed by a plurality of apparatuses. 
     INDUSTRIAL APPLICABILITY 
     According to the present invention, users can easily know content which others are allowed to check out.