Abstract:
A storage device and method stores tuning-frequency data, and extracts a tuning frequency from a received signal. Based on the stored tuning-frequency data, the tuning frequency extracted by the first extracting unit is adjusted. The storage device is accessed by an information processing apparatus, and data from the storage device are processed by an information processing method.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to storage devices and methods, information processing apparatuses and methods, and provision media therefor, and in particular, to a storage device and method for providing a memory card capable of reading and writing data in which changes in a tuning frequency are suppressed, an information processing apparatus and method using the storage device and method, and a provision medium therefor. 
     2. Description of the Related Art 
     In recent years, memory cards, in which the storage capacity is greatly increased by providing semiconductor chips such as integrated chips for storing and processing information (data), have been widely used as data cards. 
     Also non-contact memory cards have recently been developed in which a built-in data-transmitting-receiving antenna circuit (coil) for transmitting or receiving an input or output radio signal is used to perform non-contact data reading and writing with an external processing apparatus by a radio system. 
     FIG. 14 shows the structure of a non-contact memory card  91 . An antenna  101  included in the memory card  91  receives radio waves from a non-contact memory-card reader-writer  92  (described below), and supplies a signal corresponding to the received radio waves to a tuning circuit  102  and a power-supply circuit  111 . The tuning circuit  102  extracts, from the signal supplied from the antenna  101 , a carrier frequency used for communication between the memory card  91  and the reader-writer  92 . 
     An amplifying circuit  103  amplifies an input signal to a predetermined level, and outputs the amplified signal. A demodulating circuit  104  demodulates the modulated signal having the carrier frequency into predetermined data. A communication control circuit  105  performs switching between data transmission and reception. A microcomputer  106  controls other blocks of the memory card  91  in accordance with a control program stored in a read only memory (ROM)  107 . Among data supplied via the communication control circuit  105 , data to be stored are supplied as required from the microcomputer  106  to an electrically erasable and programmable read only memory (EEPROM)  108 . 
     The EEPROM  108  stores the data supplied from the microcomputer  106 . A modulating circuit  109  modulates the data supplied from the communication control circuit  105  into a signal having the carrier frequency, and outputs it. An amplifying circuit  110  amplifies the modulated signal having the carrier frequency, supplied from the modulating circuit  109 , to a level necessary for communication. The antenna  101  uses radio waves to transmit the carrier frequency signal amplified by the amplifying circuit  110 . 
     FIG. 15 shows the structure of a non-contact memory-card reader-writer  92 . An antenna  121  transmits a predetermined signal to the memory card  91  and performs transmission and reception of predetermined carrier waves in order to communicate with the memory card  91 . The antenna  121  also generates an electromagnetic field for supplying power to the memory card  91 . 
     A tuning circuit  122  extracts, from a signal supplied from the antenna  121 , the carrier frequency used for communication between the memory card  91  and the reader-writer  92 . An amplifying circuit  123  amplifies the input signal to a predetermined level, and outputs it. A demodulating circuit  124  demodulates the modulated signal having the carrier frequency into predetermined data. A communication control circuit  125  performs switching between data transmission and reception, and communication control. A microcomputer  126  controls other blocks of the reader-writer  92  in accordance with a control program stored in the ROM  128 . Among the data supplied via the communication control circuit  125 , data to be stored are supplied as required from the microcomputer  126  to a random access memory (RAM)  129 . 
     The RAM  129  stores the data supplied from the microcomputer  126 . A modulating circuit  130  modulates data supplied from the communication control circuit  125  into a signal having a carrier frequency, and outputs it. An amplifying circuit  131  amplifies the modulated signal having the carrier frequency, supplied from the modulating circuit  130 , to a level necessary for communication. The antenna  121  uses radio waves to transmit the amplified signal having the carrier frequency. 
     The above-described conventional memory cards have a problem in that performance deteriorates since a tuning frequency varies due to variations in the quality of components. 
     SUMMARY OF THE INVENTION 
     Accordingly, it is an object of the present invention to provide a storage device and method in which the tuning frequency of a memory card is adjusted to prevent performance from deteriorating, an information processing apparatus and method using the storage device and method, and a provision medium therefor. 
     To this end, according to an aspect of the present invention, the foregoing object is achieved through provision of a storage device for storing and processing information and for performing information transmission and reception with an external unit. The storage device includes a storage unit for storing tuning-frequency data, an extracting unit for extracting a tuning frequency from a received signal, and an adjusting unit for adjusting, based on the tuning-frequency data stored in the storage unit, the tuning frequency extracted by the extracting unit. 
     According to another aspect of the present invention, the foregoing object is achieved through provision of a storage method for storing and processing information and for performing information transmission and reception with an external unit. The storage method includes the steps of storing tuning-frequency data, extracting a tuning frequency from a received signal, and adjusting, based on the tuning-frequency data stored in the storing step, the tuning frequency extracted in the extracting step. 
     According to a further aspect of the present invention, the foregoing object is achieved through provision of a provision medium for providing a program to a storage device for storing and processing information and for performing information transmission and reception with an external unit. The program causes the storage device to execute a process including the steps of storing tuning-frequency data, extracting a tuning frequency from the received signal, and adjusting, based on the tuning-frequency data stored in the storing step, the tuning frequency extracted in the extracting step. 
     According to a still further aspect of the present invention, the foregoing object is achieved through provision of an information processing apparatus for accessing a non-contact storage method. The information processing method includes the steps of extracting a tuning frequency from a received signal, adjusting the tuning frequency extracted in the extracting step, and storing data read from the non-contact storage device. 
     According to yet another aspect of the present invention, the foregoing object is achieved through provision of a provision medium for providing a program to an information processing apparatus for accessing a non-contact storage device. The program causes the information processing apparatus to execute a process including the steps of extracting a tuning frequency from a received signal, adjusting the tuning frequency extracted in the extracting step, and storing data read from the non-contact storage device. 
     According to the present invention, a tuning frequency is adjusted based on a stored tuning frequency, whereby performance can be prevented from deteriorating. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a block diagram showing a memory card  1  according to an embodiment of the present invention; 
     FIG. 2 is a block diagram showing a non-contact memory-card reader-writer  2  according to an embodiment of the present invention; 
     FIG. 3 is an illustration of a data structure in an EEPROM  18  in the memory card  1  shown in FIG. 1; 
     FIG. 4 is a flowchart illustrating a process in which a reader-writer  2  searches for an optimal tuning frequency; 
     FIG. 5 is a flowchart following the flowchart shown in FIG. 4; 
     FIG. 6 is a flowchart illustrating a process performed when the memory card  1  has small storage capacity; 
     FIG. 7 is a flowchart illustrating a process in which the reader-writer  2  processes data by counting the number of errors in communication; 
     FIG. 8 is a flowchart following the flowchart shown in FIG. 7; 
     FIG. 9 is a block diagram showing a reader-writer  2  according to an embodiment of the present invention; 
     FIG. 10 is a flowchart illustrating a process in which the power supply of a display driver in the reader-writer  2  (shown in FIG. 9) is switched on; 
     FIG. 11 is a flowchart illustrating a process in which the reader-writer  2  (shown in FIG. 9) identifies the desired memory card, based on identification data; 
     FIG. 12 is a block diagram showing a reader-writer  2  according to an embodiment of the present invention; 
     FIG. 13 is a flowchart illustrating a process in which the reader-writer  2  (shown in FIG. 12) determines a communicatable distance with the memory card  1 ; 
     FIG. 14 is a block diagram showing a conventional memory card  91 ; and 
     FIG. 15 is a block diagram showing a conventional memory card  92 . 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     FIG. 1 shows a non-contact memory card  1  according to an embodiment of the present invention. An antenna  11  included in the memory card  1  receives radio waves from a reader-writer  2  (described below), and supplies a signal corresponding to the received radio waves to a tuning circuit  12  and a power supply circuit  21 . The tuning circuit  12  extracts, from the signal supplied from the antenna  11 , a carrier frequency used for communication between the memory card  1  and the reader-writer  2 . 
     An amplifying circuit  13  amplifies an input signal to a predetermined level, and outputs it. A demodulating circuit  14  demodulates the modulated signal having the carrier frequency into predetermined data. A communication control circuit  15  performs switching between data transmission and reception. A microcomputer  16  controls other blocks of the memory card  1  in accordance with a control program stored in a ROM  17 . Among data supplied via the communication control circuit  15 , data to be stored are supplied as required from the microcomputer  16  to an EEPROM  18 . 
     The EEPROM  18  stores the data supplied from the microcomputer  16 . In the EEPROM  18  (as a tuning frequency area  64  described below), tuning-frequency data of the memory card  1  are written beforehand at the time of production. 
     The modulating circuit  19  modulates the data supplied from the communication control circuit  15  into a signal having a carrier frequency, and outputs it. An amplifying circuit  20  amplifies the modulated signal having the carrier frequency, supplied from the modulating circuit  19 , to a level necessary for communication. The antenna  11  uses radio waves to transmit the carrier frequency signal amplified by the amplifying circuit  20 . 
     Regarding the operation of the antenna  11 , a process in which the antenna  11  receives radio waves transmitted from the reader-writer  2  and stores them in the EEPROM  18  is described below. 
     The radio waves received by the antenna  11  are converted into a corresponding electric signal, and the electric signal is supplied to the tuning circuit  12 . The tuning circuit  12  extracts only a signal corresponding to the predetermined carrier frequency from the signal supplied from the antenna  11 , and supplies it to the amplifying circuit  13 . The amplifying circuit  13  amplifies the supplied signal to a predetermined signal level, and supplies it to the demodulating circuit  14 . 
     The demodulating circuit  14  demodulates the signal supplied from the amplifying circuit  13 , and supplies it to the communication control circuit  15 . At this time, the mode of the communication control circuit  15  has been switched to the receiving mode. The communication control circuit  15  converts the signal supplied from the demodulating circuit  14  into digital data, and supplies them to the microcomputer  16 . The microcomputer  16  determines whether the data supplied from the communication control circuit  15  should be stored. Based on determination, the supplied data are supplied and stored in the EEPROM  18  as required. 
     The electric signal from the antenna  11  is supplied to also the power supply circuit  21 . The power supply circuit  21  extracts energy by using electromagnetic coupling with the carrier transmitted from the reader-writer  2 , whereby necessary power is supplied to each block of the memory card  1 . Power is supplied from the exterior to the memory card  1 , as described above. 
     A process for the case where the data (from reader-writer  2 ) supplied from the communication control circuit  15  represent a request for transmitting the data stored in the EEPROM  18  is described below. 
     When the microcomputer  16  receives data (command) corresponding to the request for transmitting the data via the communication control circuit  15 , it reads data from the EEPROM  18 , and supplies the data to the communication control circuit  15 . The communication control circuit  15  switches its mode to the transmission mode, and supplies the modulating circuit  19  with the data from the microcomputer  16 . 
     The modulating circuit  19  modulates the signal supplied from the communication control circuit  15  into a signal having a carrier frequency, and supplies the modulated signal to the amplifying circuit  20 . The amplifying circuit  20  amplifies the supplied signal to a level necessary for communication. The signal amplified by the amplifying circuit  20  is transmitted via the antenna  11 . 
     FIG. 2 shows the structure of a non-contact memory-card reader-writer  2  according to an embodiment of the present invention. An antenna  31  transmits a predetermined signal to the memory card  1 , and performs transmission and reception of a predetermined carrier in order to establish communication with the memory card  1 . The antenna  31  generates an electromagnetic field for supplying power to the memory card  1 . 
     A tuning circuit  32  extracts, from the signal supplied from the antenna  31 , a carrier frequency used for communication between the memory card  1  and the reader-writer  2 . An amplifying circuit  33  amplifies an input signal to a predetermined level, and outputs it. A demodulating circuit  34  demodulates the modulated signal having the carrier frequency into predetermined data. A communication control circuit  35  performs switching between data transmission and reception, and controls communication. 
     A microcomputer  36  controls other blocks of the reader-writer  2  in accordance with a control program stored in the ROM  38 . The microcomputer  36  also adjusts, based on tuning-frequency data supplied via the communication control circuit  35 , the capacitance of a variable capacitor (not shown) in the tuning circuit  32 . In other words, the microcomputer  36  adjusts a tuning frequency. The capacitance of the variable capacitor is adjusted by reading a capacitance corresponding to the tuning-frequency data stored in the ROM  38 . Among the data supplied via the communication control circuit  35 , data to be stored are supplied to a RAM  39  by the microcomputer  36 , as required. 
     A RAM  39  stores the data supplied from the microcomputer  36 . A modulating circuit  40  modulates the data supplied from the communication control circuit  35  into a signal having a carrier frequency, and outputs it. An amplifying circuit  41  amplifies the modulated signal supplied from the modulating circuit  40  to a level necessary for communication. The antenna  31  uses radio waves to transmit the amplified carrier-frequency signal. 
     Regarding the operation of the reader-writer  2 , a process in which the reader-writer  2  receives data transmitted from the memory card  1  is described below. The carrier from the memory card  1 , received by the antenna  31 , is converted into a corresponding electric signal, and the electric signal is supplied to the tuning circuit  32 . The tuning circuit  32  extracts, from the signal supplied from the antenna  31 , a signal having the predetermined frequency, and supplies it to the amplifying circuit  33 . The amplifying circuit  33  amplifies the signal supplied from the tuning circuit  32  to a predetermined signal level, and supplies it to the demodulating circuit  34 . 
     The demodulating circuit  34  demodulates the modulated signal, and supplies it to the communication control circuit  35 . The mode of the communication control circuit  35  is switched to the receiving mode. The communication control circuit  35  converts the signal supplied from the demodulating circuit  34  into digital data, and supplies them to the microcomputer  36 . The microcomputer  36  temporarily stores, in the RAM  39 , the data supplied from the communication control circuit  35 . Subsequently, the microcomputer  36  transmits the stored data to an external circuit (not shown) via a communication line  37 . 
     A process in which a data transmission request is generated and the predetermined data are transmitted from the reader-writer  2  to the memory card  1  is described below. 
     In such a case, data or the like to be stored in the memory card  1  are transmitted from the external circuit to the microcomputer  36  via the communication line  37 , as required. The microcomputer  36  supplies the communication control circuit  35  with the data supplied via the communication line  37  or the data stored in the RAM  39 . 
     The communication control circuit  35  converts the data supplied from the microcomputer  36  into an analog signal, and supplies it to the modulating circuit  40 . The modulating circuit  40  modulates the signal supplied from the communication control circuit  35  into a signal having a predetermined carrier frequency, and supplies it to the amplifying circuit  41 . The amplifying circuit  41  amplifies the signal supplied from the modulating circuit  40  to a level necessary for communication, and transmits the amplified signal via the antenna  31 . 
     The transmitted signal via the antenna  31  is received by the antenna  11  in the memory card  1 , and are written in the EEPROM  18 , as described above. 
     Thereby, data can be transmitted and received between the memory card  1  and the reader-writer  2 . 
     FIG. 3 shows an example of the structure of data stored in the EEPROM  18 . As shown in FIG. 3, the EEPROM  18  includes a card data area  51 , a program management area  52 , and a program data area  53 . The card data area  51  includes a memory capacity area  61 , an application identification (ID) area  62 , a medium ID area  63 , and a tuning frequency area  64  in which the tuning frequency of the memory card  1  is stored. 
     A process performed when the reader-writer  2  makes an automatic search for an optimal tuning frequency by using the microcomputer  36  to control the capacitance of the variable capacitor in the tuning circuit  32  is described below with reference to the flowcharts shown in FIGS. 4 and 5. 
     In step S 1 , the microcomputer  36  sets the capacitance of the tuning circuit  32  to a default value (corresponding to a predetermined tuning frequency), and proceeds to step S 2 . In step S 2 , the microcomputer  36  requests the memory card  1  to read the data stored in the EEPROM  18 . 
     In step S 3 , the microcomputer  36  determines whether a response time of the memory card  1  is not greater than a predetermined time. If the response time is not greater than the predetermined time, the microcomputer  36  proceeds to step S 4 , and determines whether the response includes a preamble and synchronization data (hereinafter referred to as “sync data”). 
     If the microcomputer  36  has determined in step S 4  that the response includes a preamble and synchronization data, the microcomputer  36  proceeds to step S 5 . In step S 5 , the microcomputer  36  reads data, and determines whether an error-detecting code has an error. If the microcomputer  36  has determined in step S 5  that the error detecting has no error, it proceeds to step S 6 , and stores the data in the RAM  39 . 
     If the microcomputer  36  has determined in step S 4  that the response includes no preamble and sync data, it returns to step S 3 , and the subsequent steps are performed again. 
     In step S 7 , the microcomputer  36  determines whether an error count is greater than a predetermined value. If the microcomputer  36  has determined in step S 7  that the error count is not greater than the predetermined value, the process is terminated. 
     In step S 3 , the microcomputer  36  has determined that the response time of the memory card  1  is greater than the predetermined time, the microcomputer  36  proceeds to step S 8 , and increases the error count by one. In step S 9 , the microcomputer  36  further increases the error count by one, so that the error count is increased by a total of two. In order that optimal control may be realized by weighting error types and evaluating the frequency of errors, the error count is increased by two when the microcomputer  36  has determined that the response time of the memory card  1  is greater than the predetermined time. 
     In step S 5 , if the microcomputer  36  has determined that the error-detecting code has an error, it proceeds to step S 9 , and increases the error count by one before proceeding to step S 10 . 
     In step S 10 , the microcomputer  36  determines whether the error count is greater than a predetermined value. If the microcomputer  36  has determined that the error count is not greater than the predetermined value, the microcomputer  36  returns to step S 2 , and the subsequent steps are performed again. 
     In steps S 7  and S 10 , if the microcomputer  36  has determined that the error count is greater than the predetermined value, the microcomputer  36  proceeds to step S 11 , and changes the capacitance of the variable capacitor in the tuning circuit  32 . 
     In step S 12 , the microcomputer  36  determines whether the changed capacitance exceeds the adjustment range of the variable capacitor. If the microcomputer  36  has determined that the changed capacitance exceeds the adjustment range of the variable capacitor, the process is terminated. If the microcomputer  36  has determined that the changed capacitance does not exceed the adjustment range of the variable capacitor, the microcomputer  36  returns to step S 2 , and the subsequent steps are performed again. 
     The tuning frequency of the memory card  1  varies depending on humidity. Accordingly, material whose dielectric constant varies depending on humidity needs to be used as material for the variable capacitor in the tuning circuit  32 . The microcomputer  36  detects a change in the dielectric constant, whereby optimal control is performed. 
     A process performed by the memory card  1  when the storage capacity of the memory card  1  is less than that of the reader-writer  2  is described below with reference to the flowchart shown in FIG.  6 . 
     In step S 21 , the microcomputer  16  determines whether the memory card  1  has received an address-designating reading request from the reader-writer  2 . If the microcomputer  16  has determined that the memory card  1  has received an address-designating reading request from the reader-writer  2 , the microcomputer  16  proceeds to step S 22 . If the microcomputer  16  has determined that the memory card  1  has received no address-designating reading request from the reader-writer  2 , the microcomputer  16  returns to step S 21 . 
     In step S 22 , the microcomputer  16  determines whether the address designated by the reader-writer  2  is within the capacity range of the EEPROM  18 . If the microcomputer  16  has determined that the address designated by the reader-writer  2  is within the capacity range of the EEPROM  18 , it proceeds to step S 23 , and reads data from the designated address. 
     In step S 22 , if the microcomputer  16  has determined that the address designated by the reader-writer  2  is not within the capacity range of the EEPROM  18 , it proceeds to step S 24 , and writes dummy data (e.g., “FFh”) in a built-in communication buffer (not shown). 
     In step S 25 , the microcomputer  16  outputs a communication start request to the communication control circuit  15 , and the process is terminated. 
     The reader-writer  2  counts the number of errors occurring in communication. If the number of errors is greater than a predetermined value, the reader-writer  2  stores the data stored in the EEPROM  18  in another memory card. This storage process is described below with reference to the flowcharts shown in FIGS. 7 and 8. 
     In step S 31 , the microcomputer  36  designates an address in the memory card  1 , and requests the memory card  1  to read data stored in an EEPROM  18 . 
     In step S 32 , the microcomputer  36  determines whether a response time of the memory card  1  is not greater than a predetermined time. If the response time is not greater than the predetermined time, the microcomputer  36  proceeds to step S 33 , and determines whether the response includes a preamble and sync data. 
     In step S 33 , if the microcomputer  36  has determined that the response includes a preamble and sync data, it proceeds to step S 34 . In step S 34 , the microcomputer  36  reads data, and determines whether an error-detecting code includes an error. If the microcomputer  36  has determined that the error-detecting code includes no error, it proceeds to step S 35 , and stores data in an RAM  39 . 
     In step S 33 , if the microcomputer  36  has determined that the response includes no preamble and sync data, it returns to step S 32 , and the subsequent steps are performed again. 
     If the microcomputer  36  has determined in step S 32  that the response time of the memory card  1  is greater than the predetermined time, or if the microcomputer  36  has determined in step S 34  that the error-detecting code includes an error, it proceeds to step S 36 , and counts errors. The microcomputer  36  returns to step S 31 , and the subsequent steps are performed again. 
     In step S 37 , the microcomputer  36  determines whether all data have been read from the memory card  1 . If the microcomputer  36  has determined that all data have not been read, it returns to step S 31 , and the subsequent steps are performed again. 
     In step S 37 , the microcomputer  36  has determined that all data have been read from the memory card  1 , it proceeds to step S 38 , and determines whether the error count is not less than a predetermined value. If the microcomputer  36  has determined that the error count is less than the predetermined value, the process is terminated. 
     In step S 38 , the microcomputer  36  has determined that the error count is greater than a predetermined value, it proceeds to step S 39 , and causes a display apparatus  72  to display a dialog box for inquiring of the user whether the data stored in the RAM  39  should be stored in a new memory card different from the memory card  1 . 
     In step S 40 , the user determines whether the data stored in the RAM  39  should be stored in the new memory card. If the user has determined that the data stored in the RAM  39  should not be stored in the new memory card, the process is terminated. If the user has determined that the data stored in the RAM  39  should be stored in the new memory card, the microcomputer  36  proceeds to step S 41 . In step S 41 , the microcomputer  36  reads and stores all the data stored in the RAM  39  in the new memory card, and the process is terminated. 
     FIG. 9 shows the structure of a reader-writer  2  according to an embodiment of the present invention. This reader-writer  2  is basically identical to that shown in FIG. 2, but differs in that a display apparatus  72 , an input circuit  73  for inputting information, and a speaker  74  for outputting sound are added. 
     A process in which the reader-writer  2  (shown in FIG. 9) switches on the power supply of a display driver  71  in association with data reception is described below with reference to the flowchart shown in FIG.  10 . 
     In step S 45 , microcomputer  36  determines whether data have been received from the memory card  1 . If the microcomputer  36  has determined that data have not been received, it returns to step S 45 . 
     In step S 45 , if the microcomputer  36  has determined that data have been received, it proceeds to step S 46 , and stores the received data in a RAM  39 . 
     In step S 47 , the microcomputer  36  sends a power-activating command to the display driver  71 , whereby the power supply of the display driver  71  is switched on, and the process is terminated. 
     A process in which the reader-writer  2  (shown in FIG. 9) uses ID data to identify the memory card  1  is described below with the flowchart shown in FIG.  11 . In this process, it is assumed that the information of the memory card  1  is stored in a ROM  38 . 
     In step S 51 , the microcomputer  36  reads a memory card information list stored in the ROM  38 , and proceeds to step S 52 . In step S 52 , the microcomputer  36  uses the display driver  71  to display the read list on the display apparatus  72 . 
     In step S 53 , the user uses the input circuit  73  to select the desired memory card from the list displayed on the display apparatus  72 . 
     In step S 54 , the user sequentially positions the reader-writer  2  to be close to each memory card. At this time, the microcomputer  36  requests the memory card to read stored data. 
     In step S 55 , the microcomputer  36  determines whether the memory card has sent a response to the request. If the microcomputer  36  has determined that no response has been received, it returns to step S 54 , and requests the memory card to read data again. If the microcomputer  36  has determined that a response has been received, it proceeds to step S 56 , and stores the read data in a RAM  39 . 
     In step S 57 , the microcomputer  36  compares the ID data of the memory card selected by the user with the ID data of the memory card. In step S 57 , if the microcomputer  36  has determined that the ID data of both memory cards do not coincide, it proceeds to step S 59 . In step S 59 , the microcomputer  36  uses the display driver  71  to display no coincidence of the ID data on the display apparatus  72 , and generates an alarm from a speaker  74 . The microcomputer  36  returns to step S 54 , and requests another memory card to read stored data again. 
     In step S 57 , if the microcomputer  36  has determined that the ID data of both memory cards coincide, it proceeds to step S 58 . In step S 58 , the microcomputer  36  uses the display driver  71  to display a coincidence of the ID data on the display apparatus  72 , and generates sound representing a coincidence from the speaker  74 . After that, the process is terminated. 
     FIG. 12 shows the structure of a reader-writer  2  according to an embodiment of the present invention. This reader-writer  2  is basically identical to that shown in FIG. 2, but differs in that a display driver  71 , a display apparatus  72 , an infrared transmitter circuit  81 , and an infrared receiver circuit  82  are added. A microcomputer  36  uses the infrared transmitter circuit  81  to transmit infrared radiation, and uses the infrared receiver circuit  82  to receive infrared radiation. An antenna  31  to an amplifying circuit  41 , the display driver  71 , and the display apparatus  72  are identical to those already described. Accordingly, descriptions thereof are omitted. 
     A process in which the reader-writer  2  (shown in FIG. 12) determines a communicable distance with the memory card  1  and initiates communication is described below with reference to the flowchart shown in FIG.  13 . 
     In step S 71 , the microcomputer  36  uses the infrared transmitter circuit  81  to transmit infrared radiation to the memory card  1  In step S 72 , the microcomputer  36  determines whether the infrared-receiver circuit  82  has received infrared radiation. The infrared receiver circuit  82  is set so as to receive the infrared radiation when the distance between the reader-writer  2  and the memory card  1  is a predetermined value. 
     In step S 72 , if the microcomputer  36  has determined that the infrared receiver circuit  82  has not received infrared radiation (communication is impossible), it returns to step S 72 . If the microcomputer  36  has determined that the infrared receiver circuit  82  has received infrared radiation (communication is possible), it proceeds to step S 73 , and enables data transmission and reception. 
     In step S 74 , the microcomputer  36  initializes a block number for reception, and requests the memory card  1  to read stored data. 
     In step S 75 , the microcomputer  36  determines whether data have been received. If the microcomputer  36  has determined that no data have been received, it returns to step S 74 , and requests the memory card  1  to read stored data again. 
     In step S 75 , if the microcomputer  36  has determined that data have been received, it proceeds to step S 76 , and stores the data in a RAM  39 . 
     In step S 77 , the microcomputer  36  determines whether all blocks of data have been received. If the microcomputer  36  has determined that all blocks have not been received, it proceeds to step S 78 . In step S 78 , the microcomputer  36  updates a block number to be received, and returns to step S 74 . 
     In step S 77 , if the microcomputer  36  has determined that all blocks have been received, the process is terminated. 
     In the present invention, the types of provision medium for providing a computer program that executes the above-described processes include not only information recording media such as magnetic disks and CD-ROMs but also network transmission media such as the Internet and digital satellite links.