PATENT DOCUMENT

Abstract:
Objects of the invention are to enable different kinds of communication apparatus having interfaces of different input/output methods and different signal voltages to be connected to the same interface; to achieve communication processing appropriate to the automatically detected attribute of the communication apparatus; to explicitly indicate optimum communication means; and to enable communications to be automatically resumed even if the communication apparatus is replaced in the middle of communication. The communication apparatus comprises: means for sending the connected state of the communication apparatus and an attribute of the communication apparatus which connected to information terminal apparatus; a signal line for sending a connection notification to the information terminal apparatus; and a signal input section and a signal output section for transferring control signals and data to and from the information terminal apparatus.

Full Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to an information terminal apparatus which is adapted to perform data communications by connecting thereto an external device such as a modem, portable telephone, car telephone, second generation cordless telephone, CDMA (code division multiple access) wireless telephone, or the like. 
     2. Description of the Related Art 
     Japanese Unexamined Patent Publication JP-A 8-307554 (1996) discloses a communication control apparatus for automatically judging the connected state of a communication terminal connected thereto and the type of the connected terminal; the apparatus comprises an AC current detection means for detecting an AC current that flows at start up through a local line to which a communication terminal is connected, and a connected device judging procedure for recognizing the attribute of the connected communication terminal based on a called signal to the communication terminal, and thereby eliminates the need for predetermining the communication terminal to be connected to the local line, allowing any desired communication terminal to be connected to each local line. 
     The above apparatus further includes a display means for displaying the attribute of the communication terminal connected to the local line so that the communication terminal attribute can be presented in a visually viewable form. Further, Japanese Unexamined Patent Publication JP-A 60-203054 (1985) discloses a controlled circuit board mounting verification method in which a central processing unit verifies the connection of a controlled circuit board, wherein a three-level input/output gate is provided which is opened and closed in a controlled manner to control a control signal from the central processing unit and whose output is connected to an external connection terminal, and wherein when a controlled circuit board is not mounted, the output gate is controlled at an high impedance state and, based on the output of the input gate, it is determined whether a controlled circuit board is mounted or not. 
     On the other hand, Japanese Unexamined Patent Publication JP-A 5-303456 (1993) discloses an information processing apparatus in which provisions are made to judge the presence or absence of a plurality of child boards mounted on a parent board, wherein the child boards are each provided, as part of a voltage dividing resistor, with a resistor whose resistance value varies for each child board, while the parent board is provided with a voltage dividing circuit which is completed when a child board is connected, and an A/D converter for measuring a voltage tapped at a designated position, and the mounting or non-mounting of a child board and the type of the mounted child board are automatically judged based on the voltage flowing when the child board is connected to the parent board. 
     The system for automatically judging the type of the connected communication terminal according to Japanese Unexamined Patent Publication JP-A 8-307554 requires the provision of an AC current detection circuit for detecting the AC current flowing from the connected communication terminal. This increases the cost. 
     The system for automatically judging the type of the connected communication terminal according to Japanese Unexamined Patent Publication JP-A 8-307554 is provided with means for visually displaying the attribute of the communication terminal connected to the local line, but is not provided with means for presenting various pieces of information associated with the characteristics of each individual communication terminal, such as transmission speed, communication charge, communication area, and the like, that become necessary when actually performing communications. 
     Likewise, according to the information processing apparatus disclosed in Japanese Unexamined Patent Publication JP-A 5-303456, the system for automatically judging the mounting of a child board requires the provision of an A/D converter for measuring a tapped voltage which varies for each child board. This increases the cost. 
     Further, the controlled circuit board mounting verification system according to Japanese Unexamined Patent Publication JP-A 60-203054 is not provided with means for automatically judging the attribute of the connected controlled circuit board, but is only intended to simply verify the connection of the predetermined controlled circuit board. 
     Furthermore, with any of the above prior art systems, connections with different kinds of communication apparatuses having interfaces of different input/output methods, different signal voltages, etc. cannot be implemented on the same interface, but only devices having the same interface can be accommodated. 
     SUMMARY OF THE INVENTION 
     An object of the present invention is to provide an information terminal apparatus at low cost that is capable of performing communications by connecting thereto any one of various kinds of external equipment of different input/output methods, having different signal voltage levels. 
     Another object of the invention is to provide an information terminal apparatus that is capable of easily making a call to the destination appropriate to the communication apparatus connected as an external device. 
     A still another object of the invention is to provide an information terminal apparatus that is capable of judging whether a communication apparatus that can achieve communications with the currently connected communication apparatus with better conditions is available or not. 
     In a first aspect of the invention an information terminal apparatus comprises an interface section for connecting thereto an external device, and a control section for performing signal transfers to and from the external device via the interface section, 
     wherein the interface section includes: 
     a connector having a terminal for sending and receiving communication control and data signals and a terminal for receiving an attribute signal representing an attribute of the external device; 
     a judging circuit for judging the attribute of the connected external device based on the received attribute signal; and 
     a switching circuit for, based on the result of the judgement, performing an operation for switching input/output directions of the communication control and data signals to directions appropriate to the connected external device and an operation for optimizing signal level to a level appropriate to the connected external device. 
     According to the information terminal apparatus of the first aspect, a communication apparatus, such as a modem, portable telephone, car telephone, second generation cordless telephone, CDMA wireless telephone, or like apparatus equipped with communication means, is connected as the external device to the information terminal apparatus equipped with means for processing data from the connected communication apparatus. By constructing the information terminal apparatus as described above, any of different kinds of communication apparatuses having interfaces of different input/output methods and different signal voltages can be connected to the same interface of the information terminal apparatus by automatically switching signals for interfacing with such communication apparatus. By providing a particular attribute notification terminal in the interface section, the input/output method and signal voltage for the interface section of the information terminal apparatus can be switched to those that match the connected communication apparatus. 
     In a second aspect the information terminal apparatus of the first aspect is characterized in that an overcurrent protection circuit is inserted in an input line used to transfer the communication control and data signals. 
     According to the information terminal apparatus of the second aspect, an overcurrent can be prevented when the communication apparatus is improperly connected to the information terminal apparatus. 
     In a third aspect of the invention the information terminal apparatus of the first aspect is characterized in that the judging circuit supplies a voltage appearing at the attribute signal receiving terminal to the control section, and the control section verifies the connection of the external device based on a voltage change on the attribute signal receiving terminal. 
     According to the information terminal apparatus of the third aspect, the communication apparatus is configured to cause the voltage on the particular notification terminal to change when it is connected to the interface section of the information terminal apparatus. In the information terminal apparatus, upon detecting the voltage change on the particular notification terminal, the judging circuit notifies the control section of the connection of the communication apparatus. 
     In a fourth aspect of the invention an information terminal apparatus comprises an interface section for connecting thereto an external device, and a control section for performing signal transfers to and from the external device via the interface section, 
     wherein the interface section includes: 
     a connector having a terminal for sending and receiving communication control and data signals and a terminal for receiving an attribute signal representing an attribute of the external device; 
     a judging circuit for judging the attribute of the connected external device based on the received attribute signal; and 
     a switching circuit for performing an operation for switching input/output directions of the communication control and data signals to directions appropriate to the connected external device and an operation for optimizing signal level to a level appropriate to the connected external device, and 
     wherein the control section verifies the connection of the external device based on the result of the judgement from the judging circuit, and causes the switching circuit to perform the signal input/output direction switching operation and the signal level optimization operation in accordance with the result of the judgement. 
     According to the information terminal apparatus of the fourth aspect, when the connection of the communication apparatus to the interface section of the information terminal apparatus is detected by the attribute signal applied to a particular notification terminal, the input/output method and signal voltage for the interface section of the information terminal apparatus are switched not in hardware fashion, but in software fashion. That is, the control section that received the result of the judgement controls the switching circuit in the interface section to switch the input/output method and signal voltage to those that match the connected communication apparatus. 
     In a fifth aspect of the invention the information terminal apparatus of the fourth invention is characterized in that the control section controls the activation and deactivation of the judging circuit and switching circuit in such a manner that when no external device is connected, only the judging circuit is activated, and when an external device is connected, the judging circuit is deactivated and the switching circuit is activated. 
     According to the information terminal apparatus of the fifth aspect, when no external device is connected to the interface section of the information terminal apparatus, the judging circuit is in the activated condition, and when a communication apparatus is connected to the interface section of the information terminal apparatus, and the attribute signal is applied to the particular notification terminal, the judging circuit is deactivated, and then the control section activates the switching circuit, thereby preventing unnecessary current from flowing. 
     In a sixth aspect of the invention the information terminal apparatus of the fourth aspect is characterized in that an overcurrent protection circuit is inserted in an input line used to transfer the communication control and data signals, and in that the control section causes the switching circuit to perform the signal input/output direction switching operation so that when no external device is connected, the communication control and data signals are transferred from the terminal to the control section. 
     According to the information terminal apparatus of the sixth aspect, when no external device is connected to the interface section of the information terminal apparatus, the entire interface section is placed in an input standby mode, and when a communication apparatus is connected to the interface section of the information terminal apparatus, and the attribute signal is applied to the particular notification terminal, the control section activates the interface section. This serves to prevent the information terminal apparatus from being damaged. 
     In a seventh aspect of the invention the information terminal apparatus of the first or fourth aspect is characterized in that a hysteresis buffer circuit is included which is connected to the attribute signal receiving terminal. 
     According to the information terminal apparatus of the seventh aspect, when a communication apparatus is connected to the interface section of the information terminal apparatus, the attribute of the connected communication apparatus can be prevented from being erroneously recognized due to chattering associated with a change occurring on the particular notification terminal. 
     In an eighth aspect of the invention the information terminal apparatus of the first or fourth aspect is characterized in that the judging circuit judges the attribute of the connected external device based on the presence or absence of the chattering of the attribute signal receiving terminal when the external device is connected. 
     According to the information terminal apparatus of the eighth aspect, assuming the use of two kinds of communication apparatuses, one provided with a hysteresis buffer circuit for preventing chattering from occurring due to a change on the particular notification terminal when the communication apparatus is connected to the interface section of the information terminal apparatus, and the other not provided with such a hysteresis buffer circuit, the attribute of the connected communication apparatus can be judged by judging whether the chattering due to a change on the particular notification terminal occurs when the communication apparatus is connected by cable. 
     In a ninth aspect of the invention an information terminal apparatus comprises an interface section for connecting thereto an external device and a control section for performing signal transfers to and from the external device via the interface section, 
     wherein the interface section includes: 
     a connector having a terminal for sending and receiving communication control and data signals, a terminal for sending an inquiry signal inquiring about the connection of the external device, and a terminal for receiving a response signal in reply to the inquiry; 
     an analyzing circuit for outputting the inquiry signal and receives the response signal; and 
     a switching circuit for performing an operation for switching input/output directions of the communication control and data signals to directions appropriate to the connected external device and an operation for optimizing signal level to a level appropriate to the connected external device, and 
     wherein when verifying the connection of the external device, the control section causes the analyzing circuit to output the inquiry signal and verifies the connection of the external device based on the response signal input to the analyzing circuit, and when the connection of the external device is verified, the control section causes the switching circuit to perform the signal input/output direction switching operation and the signal level optimization operation. 
     According to the information terminal apparatus of the ninth aspect, a communication apparatus is provided with a circuit for responding to the inquiry from the information terminal apparatus by returning a response unique to the communication apparatus. The inquiry signal output from the information terminal apparatus is processed by the responding circuit in the communication apparatus, and the returned response signal is analyzed by the information terminal apparatus, thereby automatically discriminating between a plurality of communication apparatuses. 
     In a tenth aspect of the invention an information terminal apparatus comprises an interface section for connecting thereto an external device, and a control section for performing signal transfers to and from the external device via the interface section, 
     wherein the interface section includes: 
     a connector having a terminal for sending and receiving communication control and data signals, a terminal for sending an inquiry signal inquiring about the connection of the external device, a terminal for receiving a response signal in reply to the inquiry, and a terminal for sending a test signal for connection testing; 
     an analyzing circuit which outputs the inquiry signal and receives the response signal; 
     a test circuit which outputs the test signal; and 
     a switching circuit which performs an operation for switching input/output directions of the communication control and data signals to directions appropriate to the connected external device and an operation for optimizing signal level to a level appropriate to the connected external device, and 
     wherein when verifying the connection of the external device, the control section causes the test circuit to output the test signal and the analyzing circuit to output the inquiry signal and verifies the connection of the external device based on the response signal input to the analyzing circuit and responsive to the test signal, and when the connection of the external device is verified, the control section causes the switching circuit to perform the signal input/output direction switching operation and the signal level optimization operation. 
     According to the information terminal apparatus of the tenth aspect, when the test output terminal in the interface section of the information terminal apparatus is held in an active state, a communication apparatus A receives the inquiry signal output from the information terminal apparatus and loops it back unchanged from the responding circuit in the communication apparatus, while a communication apparatus B outputs a fixed response signal from its responding circuit regardless of the inquiry signal received from the information terminal apparatus; the information terminal apparatus discriminates between the communication apparatus A and communication apparatus B by examining the contents of the transmitted inquiry signal and the received response signal. 
     In an eleventh aspect of the invention an information terminal apparatus comprises an interface section for connecting thereto an external device, and a control section for performing signal transfers to and from the external device via the interface section, 
     wherein the interface section includes: 
     a connector having a terminal for sending and receiving communication control and data signals, a terminal for receiving an attribute signal representing an attribute of the external device, a terminal for sending a test signal for connection testing, and a terminal for receiving a test result signal; 
     a judging circuit for judging the attribute of the connected external device based on the received attribute signal; 
     a test circuit for outputting the test signal and receiving the test result signal; and 
     a switching circuit for performing an operation for switching input/output directions of the communication control and data signals to directions appropriate to the connected external device and an operation for optimizing signal level to a level appropriate to the connected external device, and 
     wherein the control section verifies the connection of the external device based on the result of the judgement from the judging circuit, and when the connection of the external device is verified, the control section causes the test circuit to output the test signal and verifies the attribute of the external device based on the test result signal returned in response to and appropriate to the test signal, and causes the switching circuit to perform the signal input/output direction switching operation and the signal level optimization operation. 
     According to the information terminal apparatus of the eleventh aspect, the communication apparatus A is provided with a responding circuit which momentarily causes a response terminal to change when an inquiry terminal in the interface section of the information terminal apparatus changes from high to low. The information terminal apparatus distinguishes the communication apparatus A from other communication apparatus by monitoring the number of occurrences of an interrupt notification caused by the change of the response terminal when the inquiry terminal is activated. 
     In a twelfth aspect of the invention the information terminal apparatus of the eleventh aspect is characterized in that the terminals on the connector are pin-type terminals, and the test result signal receiving terminal is shorter than the attribute signal receiving terminal, and the control section verifies the attribute of the connected external device based on the length of time between the time the connection of the test result signal receiving terminal is detected and the time the connection of the attribute signal receiving terminal is detected. 
     According to the information terminal apparatus of the twelfth aspect, the length of the particular notification terminal pin is varied for each communication apparatus, and the attribute of the connected communication apparatus is judged based on the time difference between the detection of another terminal and the detection of the particular notification terminal when connecting the communication apparatus to the interface section of the information terminal apparatus. 
     In a thirteenth aspect of the invention the information terminal apparatus of the eleventh aspect is characterized in that the terminals on the connector have a plurality of contact faces, and the control section verifies the attribute of the connected external device based on the number of contact faces on the terminals. 
     According to the information terminal apparatus of the thirteenth invention, the number of contact faces on a particular notification terminal is varied for each communication apparatus, and the attribute of the connected communication apparatus is judged based on the number of occurrences of a change on the particular notification terminal when connecting the communication apparatus to the interface section of the information terminal apparatus. 
     In a fourteenth aspect of the invention the information terminal apparatus of the first or fourth aspect is characterized in that the judging circuit judges the attribute of the connected external device to determine whether the external device is in a power ON state or in a power OFF or unknown power state. 
     According to the information terminal apparatus of the fourteenth aspect, to automatically discriminate between the communication apparatus A having a signal line control function and the communication apparatus B not having a signal line control function, the control section of the information terminal apparatus first checks the presence or absence of the signal line control function when a communication apparatus is connected to the interface section of the information terminal apparatus, and thereby determines one of two states, a state in which the communication apparatus A in a power ON state is connected or a state in which the communication apparatus A in a power OFF state or the communication apparatus B in an unknown power state is connected. 
     In a fifteenth aspect of the invention the information terminal apparatus of the fourteenth aspect is characterized in that, when the connected external device is judged by the judging circuit to be in the power OFF or unknown power state, if there occurs a change in terminal potential, the judging circuit then determines that the connected external device has changed to the power ON state. 
     According to the information terminal apparatus of the fifteenth aspect, when the communication apparatus connected to the interface section of the information terminal apparatus is judged to be either the communication apparatus A in the power OFF state or the communication apparatus B in an unknown power state, if the connected communication apparatus is the communication apparatus A, a change will occur on the response terminal when the communication apparatus A changes from the power OFF to the power ON state; therefore, by detecting this change, it is determined that the communication apparatus in the power ON state is connected. 
     In a sixteenth aspect of the invention the information terminal apparatus of the fourteenth aspect is characterized in that, when a communication start request signal is output from the control section, the judging circuit performs the operation of judging the attribute of the connected external device. 
     According to the information terminal apparatus of the sixteenth aspect, when a communication apparatus is connected to the interface section of the information terminal apparatus, automatic detection of the connected communication apparatus using the signal line control function is not performed until after the communication start request is issued from the control section, in order to avoid consuming unnecessary power; when the communication start request is issued, the communication apparatus A having the signal line control function is preferentially tried to start communication with speed A, thereby judging the attribute of the connected communication apparatus and accomplishing the communication initiation procedure. 
     In a seventeenth aspect of the invention the information terminal apparatus of the fourteenth aspect is characterized in that, when the connected external device is judged by the judging circuit to be in the power OFF or unknown power state, the control section performs a communication operation procedure for each different type of communication apparatus, and if the communication operation procedure succeeds, the judging circuit determines that the connected external device has changed to the power ON state. 
     According to the information terminal apparatus of the seventeenth aspect, the inquiry terminal and response terminal in the interface section are made common to the communication apparatus A of speed A, the communication apparatus B of speed B, and a plurality of other communication apparatuses N of different speeds N, and when a communication apparatus is connected to the interface section, the transmission speed of the inquiry terminal and response terminal in the interface section of the information terminal apparatus is set to speed A, speed B, and speed N in sequence, thereby sequentially trying the communication operation procedure with different speeds for the communication apparatus and thus identifying the connected communication apparatus. 
     In an eighteenth aspect of the invention the information terminal apparatus of the first or fourth aspect is characterized in that the external device is a communication apparatus, and when a call arrives at the connected communication apparatus, the judging circuit judges the attribute of the connected communication apparatus based on a terminal potential change or an input signal pattern. 
     According to the information terminal apparatus of the eighteenth aspect, to automatically discriminate between the communication apparatus A of speed A equipped with a signal line control function whereby the terminal potential changes at the time of a call arrival and the communication apparatus B of speed B not equipped with a signal line control function but configured to send an input signal of a particular pattern at the time of a call arrival, there is provided a means for notifying the control section upon detecting, at the time of a call arrival, the terminal potential change or the input signal appearing at the response terminal set up with speed B, whereupon the control section of the information terminal apparatus judges the attribute of the called communication apparatus by checking the terminal potential change or the pattern of the input signal at the response terminal. 
     In a nineteenth aspect of the invention the information terminal apparatus of the eighteenth aspect is characterized in that the judging circuit judges the attribute of the connected communication apparatus based on the terminal potential change or the input signal at a predetermined terminal. 
     According to the information terminal apparatus of the nineteenth aspect, with the provision of the means for notifying the control section, at the time of a call arrival, of the occurrence of a terminal potential change or the existence of an input signal of a particular pattern on the response terminal set up with speed B, the control section of the information terminal apparatus judges the attribute of the called communication apparatus without having to check the pattern of the input signal at the response terminal. 
     In a twentieth aspect of the invention the information terminal apparatus of the eighteenth aspect is characterized in that the judging circuit judges the attribute of the connected communication apparatus based on whether or not the input signal pattern matches a preset signal pattern. 
     According to the information terminal apparatus of the twentieth invention, with the provision of the means for notifying the control section, at the time of a call arrival, of the occurrence of a terminal potential change or the existence of an input signal of a particular pattern on the response terminal set up with speed B, and with provisions made to make the particular input signal pattern settable in hardware, the control section of the information terminal apparatus judges the attribute of the called communication apparatus without having to check the pattern of the input signal at the response terminal. 
     In a twenty-first aspect of the invention an information terminal apparatus comprises an interface section for connecting thereto a communication apparatus and a control section for performing signal transfers to and from the communication apparatus via the interface section, 
     wherein the interface section includes: 
     a judging circuit for judging the attribute of the connected communication apparatus; and 
     a switching circuit for, based on the result of the judgement, performing an operation for switching input/output directions of the communication control and data signals to directions appropriate to the connected communication apparatus and an operation for optimizing signal level to a level appropriate to the connected communication apparatus, and 
     wherein when a communication application is started after the communication apparatus is connected, the control section executes a call origination procedure by retrieving connection destination information associated with the connected communication apparatus from a table in which connection destination information is prestored for each individual communication apparatus, 
     According to the information terminal apparatus of the twenty-first aspect, with the interface having a particular notification terminal capable of communicating with communication apparatus of various kinds having interfaces of different input/output methods and different signal voltages, such as a modem, portable telephone, car telephone, second generation cordless telephone, and CDMA wireless telephone, and with the provision of means for automatically detecting the connected state of the communication apparatus and the attribute of the connected communication apparatus and thereby automatically switching the input/output method and signal voltage for the interface section to those that match the connected communication apparatus, any of the different kinds of communication apparatuses can be connected to the information terminal apparatus by automatically switching signals for interfacing with such communication apparatus; when a communication application is started, the information terminal apparatus retrieves connection destination information, such as destination telephone number, for the currently connected communication apparatus from the connection destination information table stored in a storage section for each individual communication apparatus, and automatically initiates a call and performs communication using a communication procedure appropriate to the connected communication apparatus. 
     In a twenty-second aspect of the invention the information terminal apparatus of the apparatus aspect is characterized in that the control section retrieves the connection destination information associated with the communication apparatus based on the result of the judgement. 
     According to the information terminal apparatus of the twenty-second aspect, when a communication apparatus is connected to the interface section of the information terminal apparatus placed in an activated state, the information terminal apparatus notifies the control section upon detecting the connection of the communication apparatus, and the control section performs call origination and communication setup procedures by retrieving from the storage section the connection destination information appropriate to the automatically recognized attribute of the connected communication apparatus. 
     In a twenty-third aspect of the invention the information terminal apparatus of the apparatus aspect is characterized in that, when no communication apparatus is connected, the control section activates only the judging circuit, and when a communication apparatus is connected, the judging circuit supplies the result of the judgement to the control section which then activates the entire information terminal apparatus. 
     According to the information terminal apparatus of the twenty-third aspect, when a communication apparatus is connected to the interface section of the information terminal apparatus placed in an inactive state, upon detecting the connection of the communication apparatus the information terminal apparatus is automatically switched to an active state, and the control section is notified accordingly, whereupon the control section proceeds to perform call origination and communication setup procedures by retrieving from the storage section the connection destination information appropriate to the automatically recognized attribute of the connected communication apparatus. 
     In a twenty-fourth aspect of the invention the information terminal apparatus of the twenty-first aspect is characterized in that, when the communication application is started after the communication apparatus is connected, the control section judges whether any other communication apparatus is available that can accomplish communication in a shorter time than the currently connected communication apparatus, and that the information terminal apparatus includes a reporting means for visually or audibly reporting the result of the judgement made by the control section. 
     According to the information terminal apparatus of the twenty-fourth aspect, when the communication application is started, the information terminal apparatus analyzes the communication time required to complete the communication based on the transmission speeds of all available communication apparatuses and using information such as the communication procedure to be used and the amount of data predicted to be transmitted and received during the communication, detects some other communication apparatus that can accomplish the communication in a shorter time than the currently connected communication apparatus, and visually presents a notification recommending the use of such other communication apparatus by lighting an LED or producing a screen display. Alternatively, when the communication application is started, the information terminal apparatus analyzes the communication time required to complete the communication based on the transmission speeds of all available communication apparatuses and using information such as the communication procedure to be used and the amount of data predicted to be transmitted and received during the time from the start to the end of the communication, detects some other communication apparatus that can accomplish the communication in a shorter time than the currently connected communication apparatus, and audibly presents a notification recommending the use of such other communication apparatus by using a buzzer, synthesized voice, etc. 
     In a twenty-fifth aspect of the invention the information terminal apparatus of the twenty-first aspect is characterized in that, when the communication application is started after the communication apparatus is connected, the control section judges whether any other communication apparatus is available that can accomplish communication with a lower communication charge than the currently connected communication apparatus, and that the information terminal apparatus includes a reporting means for visually or audibly reporting the result of the judgement made by the control section. 
     According to the information terminal apparatus of the twenty-fifth aspect, when the communication application is started, the information terminal apparatus calculates the communication charge for the communication based on the transmission speeds of all available communication apparatuses and the communication tariff information stored in the storage section for the communication apparatuses and on information such as the communication procedure to be used and the amount of data and the number of packets predicted to be transmitted and received during the time from the start to the end of the communication, detects some other communication apparatus that can accomplish the communication with a lower communication charge than the currently connected communication apparatus, and visually presents a notification recommending the use of such other communication apparatus by lighting an LED or producing a screen display. Alternatively, when the communication application is started, the information terminal apparatus calculates the communication charge for the communication based on the transmission speeds of all available communication apparatuses and the communication tariff information stored in the storage section for the communication apparatuses and on information such as the communication procedure to be used and the amount of data and the number of packets predicted to be transmitted and received during the time from the start to the end of the communication, detects some other communication apparatus that can accomplish the communication with a lower communication charge than the currently connected communication apparatus, and audibly presents a notification recommending the use of such other communication apparatus by using a buzzer, synthesized voice, etc. 
     In a twenty-sixth aspect of the invention the information terminal apparatus of the twenty-first aspect is characterized in that, when the communication application is started after the communication apparatus is connected, the control section judges whether any other communication apparatus is available that can perform communication with a higher signal level than the signal level on a communication line of the currently connected communication apparatus, and that the information terminal apparatus includes a reporting means for visually or audibly reporting the result of the judgement made by the control section. 
     According to the information terminal apparatus of the twenty-sixth aspect, when the communication application is started, the information terminal apparatus detects communication line conditions such as radio wave conditions for the currently connected communication apparatus and, when it is determined that the communication line conditions have worsened, detects some other communication apparatus having a wider communication area from the communication area information stored in the storage section for all communication apparatuses, and visually presents a notification recommending the use of such other communication apparatus by lighting an LED or producing a screen display. Alternatively, when the communication application is started, the information terminal apparatus detects communication line conditions such as radio wave conditions for the currently connected communication apparatus and, when it is determined that the communication line conditions have worsened, detects some other communication apparatus having a wider communication area from the communication area information stored in the storage section for all communication apparatuses, and audibly presents a notification recommending the use of such other communication apparatus by using a buzzer, synthesized voice, etc. 
     In a twenty-seventh aspect of the invention the information terminal apparatus of the twenty-first aspect is characterized in that the control section suspends communication when the communication becomes impossible, and resumes the communication when the communication becomes possible, and while the communication is being suspended, the control section judges whether any other communication apparatus is available that has a wider communication area than the communication area of the currently connected communication apparatus, and that the information terminal apparatus includes a reporting means for visually or audibly reporting the result of the judgement-made by the control section. 
     According to the information terminal apparatus of the twenty-seventh aspect, the information terminal apparatus detects communication line conditions such as radio wave conditions for the communication apparatus currently performing the communication and, when it is determined that the communication apparatus is put in a communication cutoff state in the middle of data communication, temporarily suspends the ongoing communication, saves the communication data state in the storage section, detects some other communication apparatus having a wider communication area from the communication area information stored in the storage section for all communication apparatuses, and visually presents a notification recommending the use of such other communication apparatus by lighting an LED or producing a screen display. Then, when the connection of new communication apparatus is detected, the call origination and communication setup procedures are again performed automatically and the communication is resumed from the point at which it was temporarily suspended. Alternatively, the information terminal apparatus detects communication line conditions such as radio wave conditions for the communication apparatus currently performing the communication and, when it is determined that the communication apparatus is put in a communication cutoff state in the middle of data communication, temporarily suspends the ongoing communication, saves the communication data state in the storage section, detects some other communication apparatus having a wider communication area from the communication area information stored in the storage section for all communication apparatuses, and audibly presents a notification recommending the use of such other communication apparatus by using a buzzer, synthesized voice, etc. Then, when the connection of a new communication apparatus is detected, the call origination and communication setup procedures are again performed automatically and the communication is resumed from the point at which it was temporarily suspended. 
     In a twenty-eighth aspect of the invention the information terminal apparatus of the twenty-first aspect is characterized in that, when the communication apparatus is disconnected from the information terminal apparatus during communication, the control section suspends the communication, and resumes the communication upon detecting the connection of the communication apparatus being restored. 
     According to the information terminal apparatus of the twenty-eighth aspect, when it is detected that the communication apparatus is disconnected from the information terminal apparatus in the middle of data communication, the ongoing communication is temporarily suspended and the communication data state is saved in the storage section. Then, when the connection of the new communication apparatus is detected, call origination and communication setup procedures appropriate to the connected communication apparatus are automatically performed to resume the communication from the point at which it was temporarily suspended. 
     According to the first to sixth and the ninth to seventeenth aspects, to enable a communication apparatus, such as a modem, portable telephone, car telephone, second generation cordless telephone, CDMA wireless telephone or like apparatus equipped with communication means, to be connected to the information terminal apparatus equipped with means for processing data from the connected communication apparatus, the communication apparatus is provided with means for sending a connection notification and an attribute of the communication apparatus, and the information terminal apparatus is provided with means for judging the attribute of the connected communication apparatus by analyzing the connection notification and attribute information sent from the communication apparatus when the communication apparatus is connected to the information terminal apparatus, and for automatically switching between an input buffer and an output buffer for transfer of control signals and data to and from the communication apparatus. This configuration provides the effect of being able to connect different kinds of communication apparatuses having interfaces of different input/output methods and different signal voltages to the same interface of the information terminal apparatus. 
     There is the further effect of being able to construct circuitry only from relatively inexpensive devices such as passive devices and gate-level active devices, achieving cost reductions in the information terminal apparatus and communication apparatus. 
     Furthermore, the provision of the overcurrent protection circuit serves to prevent an overcurrent from flowing into the information terminal apparatus if the information terminal apparatus erroneously judges the attribute of the communication apparatus and erroneously switches the interface in the event of a failure of the attribute notification circuit in the communication apparatus. 
     According to the seventh and eighth aspects, since the judging circuit used to judge the attribute of the communication apparatus is provided with a hysteresis characteristic, chattering is eliminated, enhancing the accuracy in the judgement of the communication apparatus attribute. 
     Furthermore, the attribute notifying circuit in the communication apparatus is provided with a hysteresis characteristic, the communication apparatus is provided with a means for processing an inquiry signal sent from the information terminal apparatus into a pattern unique to the communication apparatus and for sending it as a response signal to the information terminal apparatus, the length of a notification terminal pin and the length of other terminal pins on the communication apparatus are varied for each communication apparatus, or the number of contact faces on the notification terminal on the communication apparatus is varied for each communication terminal. With these arrangements, an increased variety of communication apparatuses can be automatically recognized. 
     According to the eighteenth to twentieth aspects, since the information terminal apparatus is provided with functions for judging the signal line control function of a communication apparatus and the transmission speed of the communication apparatus and for implementing a communication-apparatus initialization procedure and various communication-protocol control procedures such as call origination procedures and call termination procedures, an increased variety of communication apparatuses can be automatically recognized by utilizing characteristics different between different kinds of communication apparatuses, such as the presence or absence of the signal line control function, different transmission speeds, and different communication protocols. 
     According to the twenty-first to twenty-third and the twenty-eighth inventions, to enable a communication apparatus, such as a modem, portable telephone, car telephone, second generation cordless telephone, CDMA wireless telephone or like apparatus equipped with communication means, to be connected to the information terminal apparatus equipped with means for processing data from the connected communication apparatus, the communication apparatus is provided with means for sending a connection notification and an attribute of the communication apparatus, and the information terminal apparatus is provided with means for judging the attribute of the connected communication apparatus by analyzing the connection notification and attribute information sent from the communication apparatus when the communication apparatus is connected to the information terminal apparatus, and for automatically switching between an input buffer and an output buffer for transfer of control signals and data to and from the communication apparatus. This configuration provides the effect of being able to connect different kinds of communication apparatuses having interfaces of different input/output methods and different signal voltages to the same interface of the information terminal apparatus. 
     Further, the provision of the means for automatically judging the attribute of the communication apparatus and the means for storing connection destination information for each communication apparatus offers the effect of being able to automatically accomplish call origination and communication setup to a destination appropriate to the communication apparatus. 
     Moreover, since the information terminal apparatus is provided with means for activating only the circuit for monitoring a connection notification from the communication apparatus when the information terminal apparatus is in an inactive state such as a sleep mode, and for switching the information terminal apparatus to the active state when the communication apparatus is connected, there is offered the effect of being able to automatically initiate the process from the activation of the information terminal apparatus to the completion of the communication by just connecting the communication apparatus. 
     According to the twenty-fourth, twenty-sixth, and twenty-seventh aspects, with the provision of means for analyzing the communication time required to complete the communication based on the transmission speeds of all available communication apparatuses and on information such as the communication procedure to be used and the amount of data predicted to be transmitted and received during the time from the start to the end of the communication, there is offered the effect of being able to indicate an optimum communication apparatus, other than the currently connected communication apparatus, using a display device or an audio output device; furthermore, not only can the currently connected communication apparatus be disconnected during data communication and be replaced with another communication apparatus, but the communication can also be initiated using a desired communication apparatus without having to make new settings at all. 
     According to the twenty-fifth aspects, with the provision of means for analyzing the communication charge for the communication based on the transmission speeds of all available communication apparatuses and communication tariff information and on information such as the communication procedure to be used and the amount of data and the number of packets predicted to be transmitted and received during the time from the start to the end of the communication, there is offered the effect of being able to indicate an optimum communication apparatus, other than the currently connected communication apparatus, using a display device or an audio output device; furthermore, not only can the currently connected communication apparatus be disconnected during data communication and be replaced with another communication apparatus, but the communication can also be initiated using a desired communication apparatus without having to make new settings at all. 
     The further effect is that when communication environmental conditions such as radio wave conditions for the currently connected communication apparatus have worsened, other communication apparatus having a wider communication area can be indicated using a display device or an audio output device. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Other and further objects, features, and advantages of the invention will be more explicit from the following detailed description taken with reference to the drawings wherein: 
     FIG. 1 is a block diagram showing the configuration for implementing an automatic signal switching operation according to a first embodiment of the present invention. 
     FIG. 2 is a diagram showing the configuration of a judging section  3  and notifying section  32  for implementing the automatic signal switching operation according to the first embodiment of the invention. 
     FIG. 3 is a diagram showing the configuration of the judging section  3  and notifying section  32  for implementing the automatic signal switching operation according to the first embodiment of the invention. 
     FIG. 4 is a flow chart illustrating the automatic signal switching operation according to the first embodiment of the invention. 
     FIG. 5 is a diagram showing the configuration of the judging section  3  and notifying section  32  for implementing the automatic signal switching operation according to the first embodiment of the invention. 
     FIG. 6 is a diagram showing the configuration of the judging section  3  and notifying section  32  for implementing the automatic signal switching operation according to the first embodiment of the invention. 
     FIG. 7 is a flow chart illustrating the automatic signal switching operation according to the first embodiment of the invention. 
     FIG. 8 is a block diagram showing the configuration for implementing an automatic signal switching operation according to a second embodiment of the invention. 
     FIG. 9 is a block diagram showing the configuration for implementing an automatic signal switching operation according to a third embodiment of the invention. 
     FIG. 10 is a block diagram showing the configuration for implementing an automatic signal switching operation according to a fourth embodiment of the invention. 
     FIG. 11 is a diagram showing the configuration of the judging section  3  and notifying section  32  for implementing the automatic signal switching operation according to the fourth embodiment of the invention. 
     FIG. 12 is a diagram showing the configuration of the judging section  3  and notifying section  32  for implementing the automatic signal switching operation according to the fourth embodiment of the invention. 
     FIG. 13 is a flow chart illustrating the automatic signal switching operation according to the fourth embodiment of the invention. 
     FIG. 14 is a diagram showing the configuration of the judging section  3  and notifying section  32  for implementing the automatic signal switching operation according to the fourth embodiment of the invention. 
     FIG. 15 is a diagram showing the configuration of the judging section  3  and notifying section  32  for implementing the automatic signal switching operation according to the fourth embodiment of the invention. 
     FIG. 16 is a flow chart illustrating the automatic signal switching operation according to the fourth embodiment of the invention. 
     FIG. 17 is a block diagram showing the configuration for implementing an automatic signal switching operation according to a fifth embodiment of the invention. 
     FIG. 18 is a block diagram showing the configuration for implementing an automatic signal switching operation according to a sixth embodiment of the invention. 
     FIG. 19 is a diagram showing the configuration of the judging section  3  and notifying section  32  for implementing an automatic signal switching operation according to a seventh embodiment of the invention. 
     FIG. 20 is a diagram showing the configuration of the judging section  3  and notifying section  32  for implementing the automatic signal switching operation according to the seventh embodiment of the invention. 
     FIG. 21 is a diagram showing the configuration of the judging section  3  and notifying section  32  for implementing an automatic signal switching operation according to an eighth embodiment of the invention. 
     FIG. 22 is a diagram showing the configuration of the judging section  3  and notifying section  32  for implementing the automatic signal switching operation according to the eighth embodiment of the invention. 
     FIG. 23 is a flow chart illustrating the automatic signal switching operation according to the eighth embodiment of the invention. 
     FIG. 24 is a block diagram showing the configuration for implementing an automatic signal switching operation according to a ninth embodiment of the invention. 
     FIG. 25 is a flow chart illustrating the automatic signal switching operation according to the ninth embodiment of the invention. 
     FIG. 26 is a block diagram showing the configuration for implementing an automatic signal switching operation according to a 10th embodiment of the invention. 
     FIG. 27 is a diagram showing the configuration of a responding section along with an analyzing signal for the automatic signal switching operation according to the 10th embodiment of the invention. 
     FIG. 28 is a diagram showing the configuration of the responding section along with the analyzing signal for the automatic signal switching operation according to the 10th embodiment of the invention. 
     FIG. 29 is a flow chart illustrating the automatic signal switching operation according to the 10th embodiment of the invention. 
     FIG. 30 is a block diagram showing the configuration for implementing an automatic signal switching operation according to 11th and 12th embodiments of the invention. 
     FIG. 31 is a diagram showing the configuration of a responding section along with an analyzing signal for the automatic signal switching operation according to the 11th embodiment of the invention. 
     FIG. 32 is a diagram showing the configuration of the responding section along with the analyzing signal for the automatic signal switching operation according to the 11th embodiment of the invention. 
     FIG. 33 is a flow chart illustrating the automatic signal switching operation according to the 11th embodiment of the invention. 
     FIG. 34 is a diagram showing the configuration of a responding section along with an analyzing signal for the automatic signal switching operation according to the 12th embodiment of the invention. 
     FIG. 35 is a diagram showing the configuration of the responding section along with the analyzing signal for the automatic signal switching operation according to the 12th embodiment of the invention. 
     FIG. 36 is a flow chart illustrating the automatic signal switching operation according to the 12th embodiment of the invention. 
     FIG. 37 is an explanatory diagram showing a communication apparatus detection process sequence for an automatic signal switching operation according to 13th and 14th embodiments of the invention. 
     FIG. 38 is an explanatory diagram showing a communication apparatus detection process sequence for an automatic signal switching operation according to a 15th embodiment of the invention. 
     FIG. 39 is an explanatory diagram showing a communication apparatus detection process sequence for an automatic signal switching operation according to a 16th embodiment of the invention. 
     FIG. 40 is an explanatory diagram showing a communication apparatus detection process sequence for an automatic signal switching operation according to a 17th embodiment of the invention. 
     FIG. 41 is an explanatory diagram showing a communication apparatus detection process sequence for an automatic signal switching operation according to an 18th embodiment of the invention. 
     FIG. 42 is an explanatory diagram showing a communication apparatus detection process sequence for an automatic signal switching operation according to a 19th embodiment of the invention. 
     FIG. 43 is a block diagram showing the configuration for implementing the automatic signal switching operation according to the 13th to 19th embodiments of the invention. 
     FIG. 44 is a block diagram showing the configuration for implementing an automatic signal switching operation according to 20th to 28th embodiments of the invention. 
     FIG. 45 is a diagram showing an example of a connection destination information table  10   a  stored in a storage section  10 . 
     FIG. 46 is a diagram showing an example of a characteristic information table  10   b  for a communication apparatus  30 , stored in the storage section  10 . 
     FIG. 47 is a diagram showing an example of a tariff information table  10   c  stored in the storage section  10 . 
     FIG. 48 is a diagram showing an example of a communication area information table  10   d  stored in the storage section  10 . 
     FIG. 49 is a flow chart illustrating the automatic signal switching operation according to the 20th embodiment of the invention. 
     FIG. 50 is a flow chart illustrating the automatic signal switching operation according to the 21st embodiment of the invention. 
     FIG. 51 is a flow chart illustrating the automatic signal switching operation according to the 22nd embodiment of the invention. 
     FIG. 52 is a flow chart illustrating the automatic signal switching operation according to the 23rd embodiment of the invention. 
     FIG. 53 is a flow chart illustrating the automatic signal switching operation according to the 24th embodiment of the invention. 
     FIG. 54 is a flow chart illustrating the automatic signal switching operation according to the 25th embodiment of the invention. 
     FIG. 55 is a flow chart illustrating the automatic signal switching operation according to the 26th embodiment of the invention. 
     FIG. 56 is a flow chart illustrating the automatic signal switching operation according to the 27th embodiment of the invention. 
     FIG. 57 is a flow chart illustrating the automatic signal switching operation according to the 27th and 28th embodiments of the invention. 
     FIG. 58 is a flow chart illustrating the automatic signal switching operation according to the 28th embodiment of the invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Now referring to the drawings, preferred embodiments of the invention are described below. 
     Embodiment 1 
     As shown in FIG. 1, an information terminal apparatus  1  comprises: a control section  2  for controlling an interface connecting between the information terminal apparatus  1  and communication apparatus  30 ; a judging section  3  for automatically judging an attribute of the connected communication apparatus  30 ; a signal line  52  for receiving a connection notification  102  from the communication apparatus  30 ; a switching section  7  for automatically switching between an input buffer  5  and an output buffer  6  in response to a switching control  108  from the judging section  3 ; a signal line  58  for transferring input/output signals  107 , such as control signals and data, between the communication apparatus  30  and the switching section  7 ; a signal line  56  for transferring control signals and data from the switching section  7  to the control section  2  via the input buffer  5 ; a signal line  57  for transferring control signals and data from the control section  2  to the switching section  7  via the output buffer  6  of an open collector type; a connector  8  accommodating terminals for connecting the signal lines to the communication apparatus  30 ; and pull up resistors  521  and  561  for providing a high level state when nothing is connected to the respective input sections and for providing an input signal of a prescribed level to an output section of the communication apparatus  30  when in a connected condition. 
     The communication apparatus  30  comprises: a notifying section  32  for sending the attribute and the connected state of the communication apparatus  30  when connected to the information terminal apparatus  1 ; a signal line  71  for sending the connection notification  102  from the notifying section  32  to the information terminal apparatus  1 ; and a signal output section  34  and a signal input section (not shown) for transferring input/output signals  107 , such as control signals and data, to and from the information terminal apparatus  1 . When the communication apparatus  30  is not connected to the information terminal apparatus  1 , the connection notification  102  is not yet sent to the judging section  3 , and the signal line  52  connected to the judging section  3  continually provides a high level state by the action of the pull up resistor  521 . Further, since the polarity of signal input/output lines on the communication apparatus  30  is unknown, the judging section  3  controls the switching section  7  by the switching control  108  so that the signal line  57  connected to the open collector type output buffer  6  is connected to the signal line  58  connected to a terminal  804  on the connector  8 . 
     When the communication apparatus  30  is connected to the information terminal apparatus  1 , the connection notification  102  from the notifying section  32  arrives at the judging section  3  at the instant that a terminal  801  on the connector  8  is connected to a terminal  311  on a connector  31 , and the judging section  3  thus judges the connected state and the attribute of the communication apparatus  30 . By configuring the notifying section  32  to generate a pattern unique to the type of the communication apparatus, the judging section  3  can judge the type of the connected communication apparatus as well as the connected state of the communication apparatus. 
     FIGS. 2 and 3 show configuration examples of the judging section  3  and notifying section  32 . FIG. 2 shows an example in which when a communication apparatus A is connected to the information terminal apparatus  1 , the judging section  3  judges the state of the signal line  52  after the connection notification  102  as being low. FIG. 3 shows an example in which when a communication apparatus B is connected to the information terminal apparatus  1 , the judging section  3  judges the state of the signal line  52  after the connection notification  102  as being high. 
     FIG. 4 shows a flow chart for judging the attribute of the connected communication apparatus. The judging process is carried out by evaluating the state of the connection notification after waiting for time T 1  necessary for connector connection from the time the connection notification is made to the time the connection is completed. When the communication apparatus is connected to the information terminal apparatus  1 , the connection notification arrives whereupon the processing sequence is started ( 1001 ). When the judging process is started, first a decision is made as to whether the time T 1  required to complete the connector connection has elapsed or not ( 1002 ). When the time T 1  has elapsed, the process exits the loop and proceeds to the next step of evaluating the state of the connection notification ( 1003 ), which is followed by the step of judging the result of the evaluation ( 1004 ). 
     In the example of FIG. 2, since the state of the connection notification after the time T 1  is low, in the next step ( 1005 ) it is determined that the communication apparatus A has been connected ( 1007 ). In the example of FIG. 3, on the other hand, since the state of the connection notification after the time T 1  is high, the result of the evaluation is judged ( 1004 ) and it is determined in the next step ( 1006 ) that the communication apparatus B has been connected, and thereafter I/F matching is performed ( 1007 ). 
     FIGS. 5 and 6 show an alternative configuration in which the judging section  3  has an attribute notification table for judging the attribute of the connected communication apparatus based on the number of pulses generated at the time of the connection notification; in this configuration, the contact on the notifying section  32  that generates the connection notification is formed with a different number of stages for different communication apparatus so that the attribute of the connected communication apparatus can be judged based on the number of pulses generated at the time of the connection notification. 
     FIG. 5 concerns an example in which when a communication apparatus C is connected to the information terminal apparatus  1 , the judging section  3  detects c- 1  clock-like pulses that follow the connection notification. FIG. 6 concerns an example in which when a communication apparatus D is connected to the information terminal apparatus  1 , the judging section  3  detects d- 1  clock-like pulses that follow the connection notification. 
     FIG. 7 shows a flow chart for judging the attribute of the connected communication apparatus. The judging process is carried out by making use of a count value which indicates the number of pulses generated during the time T 1  necessary for connector connection from the time the connection notification is made to the time the connection is completed. When the communication apparatus is connected to the information terminal apparatus  1 , the connection notification arrives, whereupon the processing sequence is started ( 2001 ). First, the count value n is initialized ( 2002 ). When the judging process is started, the step of incrementing the count by the rising edge of each pulse is carried out ( 2003 ). This step is carried out repeatedly during the time T 1 , with the process looping back from the next step of judging the elapsed time ( 2004 ). When the time T 1  has elapsed, the process exits the loop and proceeds to the next step ( 2005 ) where the count value at the end of the time T 1  is evaluated. In the example of FIG. 5, since the judging section  3  detects c- 1  pulse rise edges that follow the connection notification, the count value n shows c- 1 ; therefore, it is determined in the next step that the communication apparatus C has been connected ( 2006 ) and I/F matching based on the determination is performed ( 2010 ). In the example of FIG. 6, on the other hand, since the judging section  3  counts d- 1  pulse rise edges that follow the connection notification, in the evaluation step ( 2005 ) n is not c- 1 , so that the process proceeds to the next evaluation step ( 2007 ) where the count value n is d- 1 ; then, the process proceeds to the next step to determine that the communication apparatus D has been connected ( 2008 ) and I/F matching is performed ( 2010 ). In either example, I/F matching can be achieved by judging an arbitrary kind of attribute based on the number of terminal stages that generate the connection notification indicating the connection of the communication apparatus. 
     In FIG. 1, matching to the characteristics of the input/output sections of the communication apparatus  30  is done by judging the attribute of the communication apparatus  30 ; to achieve this, the judging section  3  sends the switching control  108  to the switching section  7  so that control signals and data can be transferred between the information terminal apparatus  1  and the communication apparatus  30 . 
     In FIG. 1, the circuit block for transferring the control signals and data between the information terminal apparatus  1  and the communication apparatus  30  is shown as having only one control path, but by providing a plurality of switching controls, an interface for transferring control signals and data using multiple paths can be achieved. 
     Embodiment 2 
     The configuration shown in FIG. 8 is the same as that of the first embodiment, except that an overcurrent protection  562  is inserted in the signal line  56  leading to the input buffer in the information terminal apparatus  1  in order to prevent an overcurrent from flowing due to a potential difference between V 1  and V 2  in case the attribute of the communication apparatus  30  is erroneously judged at the time of the connection of the communication apparatus  30  with the information terminal apparatus  1 , accidentally performing such switching control  108  that the signal input/output line  58 , which leads to the terminal  804  on the information terminal apparatus  1  connected to the signal input section  35  pulled up by V 2  (V) in the communication apparatus  30 , is connected to the signal line  56  pulled up by V 1  (V) 
     Embodiment 3 
     As shown in FIG. 9, in a third embodiment, an information terminal apparatus  1  comprises: a control section  2  for controlling an interface connecting between the information terminal apparatus  1  and communication apparatus  30 ; a judging section  3  for automatically judging an attribute of the connected communication apparatus  30 ; a signal line  52  for receiving a connection notification  102  from the communication apparatus  30 ; a switching section  7  for automatically switching between an input buffer  5  and an output buffer  6  in response to a switching control  108  from the judging section  3 ; an interrupt line  51  for reporting a judgement result  101  from the judging section  3  to the control section  2 ; a signal line  58  for transferring input/output signals  107 , such as control signals and data, between the communication apparatus  30  and the switching section  7 ; a signal line  56  for transferring control signals and data from the switching section  7  to the control section  2  via the input buffer  5 ; a signal line  57  for transferring control signals and data from the control section  2  to the switching section  7  via the output buffer  6  of an open collector type; a connector  8  accommodating terminals for connecting the signal lines to the communication apparatus  30 ; and pull up resistors  521  and  561  for providing a high level state when nothing is connected to the respective input sections and for providing an input signal of a prescribed level to an output section of the communication apparatus  30  when in a connected condition. 
     The communication apparatus  30  comprises: a notifying section  32  for sending the attribute and the connected state of the communication apparatus  30  when connected to the information terminal apparatus  1 ; a signal line  71  for sending the connection notification  102  from the notifying section  32  to the information terminal apparatus  1 ; and a signal output section  34  and a signal input section (not shown) for transferring input/output signals  107 , such as control signals and data, to and from the information terminal apparatus  1 . 
     When the communication apparatus  30  is not connected to the information terminal apparatus  1 , the connection notification  102  is not yet sent to the judging section  3 , and the signal line  52  connected to the judging section  3  continually provides a high level state by the action of the pull up resistor  521 . Further, since the polarity of signal input/output lines on the communication apparatus  30  is unknown, the judging section  3  controls the switching section  7  by the switching control  108  so that the signal line  57  connected to the open collector type output buffer  6  is connected to the signal line  58  connected to a terminal  804  on the connector  8 . 
     When the communication apparatus  30  is connected to the information terminal apparatus  1 , the connection notification  102  from the notifying section  32  arrives at the judging section  3  at the instant that a terminal  801  on the connector  8  is connected to a terminal  311  on a connector  31 , and the judging section  3  thus judges the connected state and the attribute of the communication apparatus  30 . By configuring the notifying section  32  to generate a pattern unique to the type of the communication apparatus, the judging section  3  can judge the type of the connected communication apparatus as well as the connected state of the communication apparatus. This method is the same as that employed in the first embodiment. Matching to the characteristics of the input/output sections of the communication apparatus  30  is done by judging the attribute of the communication apparatus  30 ; to achieve this, the judging section  3  sends the switching control  108  to the switching section  7  so that control signals and data can be transferred between the information terminal apparatus  1  and the communication apparatus  30 . At the same time, the judging section  3  generates a signal for reporting the judgement result  101  to the control section  2 , and outputs the signal on the interrupt line  51 . 
     In FIG. 9, the circuit block for transferring the control signals and data between the information terminal apparatus  1  and the communication apparatus  30  is shown as having only one control path, but by providing a plurality of switching controls, an interface for transferring control signals and data using multiple paths can be achieved. 
     Embodiment 4 
     As shown in FIG. 10, in a fourth embodiment, an information terminal apparatus  1  comprises: a control section  2  for controlling an interface connecting between the information terminal apparatus  1  and communication apparatus  30 ; a judging section  3 , connected to the control section  2 , for producing a report corresponding to a connection notification  102  received from the communication apparatus  30 ; a signal line  52  for the judging section  3  to receive the connection notification  102  from the communication apparatus  30 ; an interrupt line  51  for reporting a judgement result  101  from the judging section  3  to the control section  2 ; a switching section  7  for automatically switching between an input buffer  5  and an output buffer  6  in response to a switching control  108  from the control section  2 ; a signal line  58  for transferring input/output signals  107 , such as control signals and data, between the communication apparatus  30  and the switching section  7 ; a signal line  56  for transferring control signals and data from the switching section  7  to the control section  2  via the input buffer  5 ; a signal line  57  for transferring control signals and data from the control section  2  to the switching section  7  via the output buffer  6  of an open collector type; a connector  8  accommodating terminals for connecting the signal lines to the communication apparatus  30 ; and pull up resistors  521  and  561  for providing a high level state when nothing is connected to the respective input sections and for providing an input signal of a prescribed level to an output section of the communication apparatus  30  when in a connected condition. 
     The communication apparatus  30  comprises: a notifying section  32  for sending the attribute and the connected state of the communication apparatus  30  when connected to the information terminal apparatus  1 ; a signal line  71  for sending the connection notification  102  from the notifying section  32  to the information terminal apparatus  1 ; and a signal output section  34  and a signal input section (not shown) for transferring input/output signals  107 , such as control signals and data, to and from the information terminal apparatus  1 . 
     When the communication apparatus  30  is not connected to the information terminal apparatus  1 , the connection notification  102  is not yet sent to the judging section  3 , and the signal line  52  connected to the judging section  3  continually provides a high level state by the action of the pull up resistor  521 . Further, since the polarity of signal input/output lines on the communication apparatus  30  is unknown, the control section  2  controls the switching section  7  by the switching control  108  so that the signal line  57  connected to the open collector type output buffer  6  is connected to the signal line  58  connected to a terminal  804  on the connector  8 . 
     When the communication apparatus  30  is connected to the information terminal apparatus  1 , the connection notification  102  from the notifying section  32  arrives at the judging section  3  at the instant that a terminal  801  on the connector  8  is connected to a terminal  311  on a connector  31 , and the judging section  3  thus generates an interrupt signal corresponding to the pattern of the connection notification  102 , and outputs the interrupt signal on the interrupt line  51  for transfer to the control section  2 . The control section  2  judges the connected state and the attribute of the communication apparatus  30  based on the interrupt signal. By configuring the notifying section  32  to generate a pattern unique to the type of the communication apparatus, the control section  2  can judge the type of the connected communication apparatus as well as the connected state of the communication apparatus. 
     FIGS. 11 and 12 show configuration examples of the judging section  3  and notifying section  32 . FIG. 11 shows an example in which when a communication apparatus A is connected to the information terminal apparatus  1 , the judging section  3  sends the connection notification interrupt signal to the control section  2  which then judges the state of the connection notification as being low. FIG. 12 shows an example in which when a communication apparatus B is connected to the information terminal apparatus  1 , the judging section  3  sends the connection notification interrupt signal to the control section  2  which then judges the state of the connection notification as being high. 
     FIG. 13 shows a flow chart for judging the attribute of the connected communication apparatus. The judging process is carried out by evaluating the state of the connection notification after waiting for time T 1  necessary for connector connection from the time the connection notification interrupt is caused to the time the connection is completed. When the communication apparatus is connected to the information terminal apparatus  1 , the connection notification interrupt occurs to initiate the processing sequence ( 3001 ). When the judging process is started, a connection notification interrupt disable step ( 3002 ) is carried out to prevent multiple occurrences of the connection notification interrupt during the time T 1 . Next, the process proceeds to a decision step ( 3003 ) where a decision is made as to whether the time T 1  necessary for the connector connection has elapsed or not. When the time T 1  has elapsed, the process exits the loop and proceeds to the next step of evaluating the state of the connection notification ( 3004 ), which is followed by the step of judging the result of the evaluation ( 3005 ). 
     In the example of FIG. 11, since the state of the connection notification passed from the judging section  3  to the control section  2  is low at the end of the time T 1 , it is determined in the next step ( 3006 ) that the communication apparatus A has been connected, and then the judging process is terminated. 
     In the example of FIG. 12, on the other hand, since the state of the connection notification passed from the judging section  3  to the control section  2  is high at the end of the time T 1 , the result of the evaluation is judged ( 3005 ) and the process proceeds to the next step ( 3007 ) where it is determined the communication apparatus B has been connected, and then the judging process is terminated. When the judging process is terminated, a connection notification interrupt enable step ( 3008 ) is carried out to enable the automatic judgement for the next communication apparatus to be connected. The whole process for judging the attribute of the communication apparatus is thus terminated, and I/F matching ( 3009 ) is performed. 
     FIGS. 14 and 15 show an alternative configuration in which the control section  2  has an attribute notification table for judging the attribute of the connected communication apparatus based on the number of attribute notification interrupts generated at the time of the connection notification; in this configuration, the contact on the notifying section  32  that generates the connection notification is formed with a different number of stages for different communication apparatus so that the attribute of the connected communication apparatus can be judged based on the number of attribute notification interrupts generated at the time of the connection notification. FIG. 14 concerns an example in which when a communication apparatus C is connected to the information terminal apparatus  1 , the control section  2  detects c- 1  times attribute notification interrupts being sent from the judging section  3 . FIG. 15 concerns an example in which when a communication apparatus D is connected to the information terminal apparatus  1 , the control section  2  detects d- 1  times attribute notification interrupts being sent from the judging section  3 . 
     FIG. 16 shows a flow chart for judging the attribute of the connected communication apparatus. The judging process is carried out by making use of a count value which indicates the number of occurrences of an attribute interrupt caused by the rising edge of a pulse during time T 1  necessary for connector connection from the time the connection notification interrupt is caused to the time the connection is completed. When the communication apparatus is connected to the information terminal apparatus  1 , the connection notification interrupt occurs to initiate the processing sequence ( 4001 ). When the judging process is started, a connection notification interrupt disable step ( 4002 ) is carried out to prevent multiple occurrences of the connection notification interrupt during the time T 1 . Next, the count value counting the number of occurrences of the attribute interrupt arising during the time T 1  is initialized ( 4003 ). 
     After carrying out an attribute interrupt enable step ( 4004 ), the process proceeds to a decision step ( 4005 ) where it is decided whether the time T 1  necessary for the connector connection has elapsed or not. When the attribute interrupt enable step ( 4004 ) is carried out in the connection interrupt process, an attribute interrupt process ( 4101 ) is initiated and carries out a step ( 4102 ) where a count of the number of attribute interrupts is incremented at each occurrence of an attribute interrupt, and thereafter the process is terminated ( 4103 ). When the waiting time T 1  necessary for the connector connection has elapsed in the connection interrupt process, an attribute interrupt disable step ( 4006 ) is carried out to prevent an illegal attribute interrupt from occurring after the time T 1  necessary for the connector connection has elapsed. Next, the process proceeds to the step ( 4007 ) of judging the attribute of the communication apparatus based on the count value obtained by counting the number of attribute interrupts. 
     In the example of FIG. 14, since the control section  2  receives the attribute interrupt c- 1  times following the occurrence of the connection notification interrupt, the count value n in the evaluation step ( 4007 ) is c- 1 , and in the next step ( 4008 ) it is determined that the communication apparatus C has been connected, whereupon the judging process is terminated. In the example of FIG. 15, on the other hand, since the control section  2  receives the attribute interrupt d- 1  times following the occurrence of the connection notification interrupt, the count value n in the evaluation step ( 4007 ) is not c- 1 , but as it is evaluated in the next step ( 4009 ), n is d- 1 ; as a result, it is determined in the next step ( 4010 ) that the communication apparatus D has been connected, whereupon the judging process is terminated. In either example, any arbitrary kind of attribute can be judged based on the number of terminal stages that generate the connection notification indicating the connection of the communication apparatus. 
     When the judging process is terminated, a connection notification interrupt enable step ( 4012 ) is carried out to enable the automatic judgement for the next communication apparatus to be connected. The whole process for judging the attribute of the connected communication apparatus is thus terminated, and I/F matching ( 4013 ) is performed. 
     In FIG. 10, matching to the characteristics of the input/output sections of the communication apparatus  30  is done by judging the attribute of the communication apparatus  30 ; to achieve this, the control section  2  sends the switching control  108  to the switching section  7  so that control signals and data can be transferred between the information terminal apparatus  1  and the communication apparatus  30 . 
     In FIG. 10, the circuit block for transferring the control signals and data between the information terminal apparatus  1  and the communication apparatus is shown as having only one control path, but by providing a plurality of switching controls, an interface for transferring control signals and data using multiple paths can be achieved. 
     Embodiment 5 
     As shown in FIG. 17, in a fifth embodiment, an information terminal apparatus  1  comprises: a control section  2  for controlling an interface connecting between the information terminal apparatus  1  and communication apparatus  30 ; a judging section  3 , connected to the control section  2 , for producing a report corresponding to a connection notification  102  received from the communication apparatus  30 ; a signal line  52  for the judging section  3  to receive the connection notification  102  from the communication apparatus  30 ; an interrupt line  51  for reporting a judgement result  101  from the judging section  3  to the control section  2 ; activation control lines  109  for automatically activating and deactivating the judging section  3  and the connecting interface respectively in reversing manner from the control section  2 ; a switching section  7  for automatically switching between an input buffer  5  and an output buffer  6  in response to a switching control  108  from the control section  2 ; a signal line  58  for transferring input/output signals  107 , such as control signals and data, between the communication apparatus  30  and the switching section  7 ; a signal line  56  for transferring control signals and data from the switching section  7  to the control section  2  via the input buffer  5 ; a signal line  57  for transferring control signals and data from the control section  2  to the switching section  7  via the output buffer  6  of an open collector type; a connector  8  accommodating terminals for connecting the signal lines to the communication apparatus  30 ; and pull up resistors  521  and  561  for providing a high level state when nothing is connected to the respective input sections and for providing an input signal of a prescribed level to an output section of the communication apparatus  30  when in a connected condition. 
     The communication apparatus  30  comprises: a notifying section  32  for sending the attribute and the connected state of the communication apparatus  30  when connected to the information terminal apparatus  1 ; a signal line  71  for sending the connection notification  102  from the notifying section  32  to the information terminal apparatus  1 ; and a signal output section  34  and a signal input section (not shown) for transferring input/output signals  107 , such as control signals and data, to and from the information terminal apparatus  1 . 
     When the communication apparatus  30  is not connected to the information terminal apparatus  1 , the connection notification  102  is not yet sent to the judging section  3 , and the signal line  52  connected to the judging section  3  continually provides a high level state by the action of the pull up resistor  521 . The control section  2  outputs control signals on the activation control lines  109  to activate only the judging section  3 , while putting the connecting interface in a deactivated state that does not consume current. 
     The judging process performed when the communication apparatus  30  is connected to the information terminal apparatus  1  is the same as that described in the fourth embodiment. Matching to the characteristics of the signal input/output sections of the communication apparatus  30  is done by judging the attribute of the communication apparatus  30 ; to achieve this, the control section  2  deactivates the judging section  3  and activates the connecting interface by activation control signals, and at the same time, sends the switching control  108  to the switching section  7  so that control signals and data can be transferred between the information terminal apparatus  1  and the communication apparatus  30 . 
     In FIG. 17, the circuit block for transferring the control signals and data between the information terminal apparatus  1  and the communication apparatus is shown as having only one control path, but by providing a plurality of switching controls, an interface for transferring control signals and data using multiple paths can be achieved. 
     Embodiment 6 
     As shown in FIG. 18, in a sixth embodiment, an information terminal apparatus  1  comprises: a control section  2  for controlling an interface connecting between the information terminal apparatus  1  and communication apparatus  30 ; a judging section  3 , connected to the control section  2 , for producing a report corresponding to a connection notification  102  received from the communication apparatus  30 ; a signal line  52  for the judging section  3  to receive the connection notification  102  from the communication apparatus  30 ; an interrupt line  51  for reporting a judgement result  101  from the judging section  3  to the control section  2 ; a switching section  7  for automatically switching between an input buffer  5  and an output buffer  6  in response to a switching control  108  from the control section  2 ; a signal line  58  for transferring input/output signals  107 , such as control signals and data, between the communication apparatus  30  and the switching section  7 ; a signal line  56  for transferring control signals and data from the switching section  7  to the control section  2  via the input buffer  5 ; a signal line  57  for transferring control signals and data from the control section  2  to the switching section  7  via the output buffer  6  of an open collector type; a connector  8  accommodating terminals for connecting the signal lines to the communication apparatus  30 ; and pull up resistors  521  and  561  for providing a high level state when nothing is connected to the respective input sections and for providing an input signal of a prescribed level to an output section of the communication apparatus  30  when in a connected condition. 
     The communication apparatus  30  comprises: a notifying section  32  for sending the attribute and the connected state of the communication apparatus  30  when connected to the information terminal apparatus  1 ; a signal line  71  for sending the connection notification  102  from the notifying section  32  to the information terminal apparatus  1 ; and a signal input section (not shown) and a signal output section  35  for transferring input/output signals  107 , such as control signals and data, to and from the information terminal apparatus  1 . 
     When the communication apparatus  30  is not connected to the information terminal apparatus  1 , the connection notification  102  is not yet sent to the judging section  3 , and the signal line  52  connected to the judging section  3  continually provides a high level state by the action of the pull up resistor  521 . Further, since the polarity of signal input/output lines on the communication apparatus  30  is unknown, the control section  2  controls the switching section  7  by the switching control  108  so that the signal line  56  connected to the input buffer  5  is connected to the signal line  58  connected to a terminal  804  on the connector  8 . 
     An overcurrent protection  562  is inserted in the signal line  56  leading to the input buffer  5  in the information terminal apparatus  1  in order to prevent an overcurrent from flowing due to a potential difference between V 1  and V 2  when a terminal on the information terminal apparatus  1  connected to a terminal on the communication apparatus, with the input polarity of the latter terminal pulled up by V 2  (V), is taken as an input pulled up by V 1  (V) during the time from the moment the communication apparatus  30  is connected to the information terminal apparatus  1  until the characteristics of the signal input/output sections of the connecting interface on the information terminal apparatus  1  are matched by judging the attribute of the communication apparatus  30 . 
     The judging process performed when the communication apparatus  30  is connected to the information terminal apparatus  1  is the same as that described in the fourth embodiment. Matching to the characteristics of the signal input/output sections of the communication apparatus  30  is done by judging the attribute of the communication apparatus  30 ; to achieve this, the control section  2  sends the switching control  108  to the switching section  7  so that control signals and data can be transferred between the information terminal apparatus  1  and the communication apparatus  30 . 
     In FIG. 18, the circuit block for transferring the control signals and data between the information terminal apparatus  1  and the communication apparatus is shown as having only one control path, but by providing a plurality of switching controls, an interface for transferring control signals and data using multiple paths can be achieved. 
     Embodiment 7 
     As shown in FIGS. 19 and 20, in a seventh embodiment, the judging section  3  for automatically judging the attribute of the connected communication apparatus has an input buffer which is provided with a hysteresis characteristic in order to prevent erroneous recognition of the connected communication apparatus due to chattering that occurs because of the mechanical action associated with connector terminal characteristics when the communication apparatus is connected to the information terminal apparatus  1 . 
     Embodiment 8 
     In an eighth embodiment, the judging section  3  in the information terminal apparatus  1  judges the attribute of the connected communication apparatus based on the number of occurrences of a connection notification during the time T 1  necessary for the connector connection from the time the connection notification is first issued to the time the connection is completed. This is accomplished by utilizing the characteristic that the number of connection notifications generated differs between the case of FIG. 21, where the notifying section  32  for reporting the attribute of the connected communication apparatus is not provided with means for suppressing the occurrence of chattering due to the mechanical action associated with connector terminal characteristics when the communication apparatus is connected to the information terminal apparatus  1 , and the case of FIG. 22, where the notifying section  32  for reporting the attribute of the connected communication apparatus is provided with means for suppressing the occurrence of chattering due to the mechanical action associated with connector terminal characteristics when the communication apparatus is connected to the information terminal apparatus  1 . 
     In the case of FIG. 21, when a communication apparatus A is connected to the information terminal apparatus  1 , chattering occurs due to the mechanical action associated with the characteristics of the connector terminals  801  and  311 , as a result of which the connection notification is sent to the judging section  3  a plurality of times during the time T 1  required to complete the connector connection. On the other hand, in the case of FIG. 22, since the chattering is suppressed by the charge/discharge time constant of a capacitive load, the connection notification is sent to the judging section  3  only once during the time T 1  required to complete the connector connection. 
     FIG. 23 shows a flow chart for judging the attribute of the connected communication apparatus. The judging process is performed by making use of a count value which indicates the number of occurrences of the connection notification during the time T 1  necessary for the connector connection from the time the connection notification is first reported to the time the connection is completed. When the communication apparatus is connected to the information terminal apparatus  1 , a connection notification arrives, whereupon the processing sequence is started ( 5001 ). When the judging process is started, first the count value n is initialized ( 5002 ). Next, the step of incrementing the count by the falling edge of each connection notification pulse is carried out ( 5003 ). This step is carried out repeatedly during the time T 1 , with the process looping back from the next step ( 5004 ) of judging the elapsed time. When the time T 1  has elapsed, the process exits the loop and proceeds to the next step ( 5005 ) where the count value at the end of the time T 1  is evaluated. In the example of FIG. 21, since the judging section  3  detects a plurality of connection notifications after the first connection notification, the count value n is sufficiently larger than  1 ; therefore, it is determined in the next step ( 5006 ) that the communication apparatus A has been connected, and the judging process is terminated, followed by I/F matching ( 5008 ). In the example of FIG. 22, on the other hand, since the judging section  3  counts only one connection notification pulse, in the evaluation step ( 5005 ) n is not sufficiently larger than  1 ; therefore, it is determined in the next step ( 5007 ) that the communication apparatus B has been connected, and the judging process is terminated, followed by I/F matching ( 5008 ). 
     Embodiment 9 
     As shown in FIG. 24, in a ninth embodiment, an information terminal apparatus  1  comprises: a control section  2  for controlling an interface connecting between the information terminal apparatus  1  and communication apparatus  30 ; an analyzing section  4  for judging the type of the connected communication apparatus  30 ; a signal line  54  for sending a type inquiry  104  from the analyzing section  4  to the communication apparatus  30 ; a signal line  55  for the analyzing section  4  to receive a type-identifying response  106  from the communication apparatus  30  in response to the type inquiry; a handling bus  53  for transferring an analysis instruction  103  and a state verification instruction  105  from the control section  2  to the analyzing section  4 ; an input buffer  5  and an output buffer  6  for transferring control signals and data to and from the communication apparatus  30 ; a switching section  7  for automatically switching between the input buffer  5  and the output buffer  6  in response to a switching control  108  that the control section  2  issues by judging the connection characteristics based on the result of the analysis of the communication apparatus  30 ; a signal line  58  for transferring input/output signals  107 , such as control signals and data, between the communication apparatus  30  and the switching section  7 ; a signal line  56  for transferring control signals and data from the switching section  7  to the control section  2  via the input buffer  5 ; a signal line  57  for transferring control signals and data from the control section  2  to the switching section  7  via the output buffer  6  of an open collector type; a connector  8  accommodating terminals for connecting the signal lines to the communication apparatus  30 ; and pull up resistors  551  and  561  for providing a high level state when nothing is connected to the respective input sections and for providing an input signal of a prescribed level to an output section of the communication apparatus  30  when in a connected condition. 
     The communication apparatus  30  comprises: a responding section  33  for generating the type-identifying response  106  identifying the type of the communication apparatus  30  in response to the type inquiry  104  from the information terminal apparatus  1 ; a signal line  72  for delivering the type inquiry from the information terminal apparatus  1  to the responding section  33 ; a signal line  73  for sending the type-identifying response  106  from the responding section  33  to the information terminal apparatus  1 ; and a signal input section (not shown) and a signal output section  34  for transferring input/output signals  107 , such as control signals and data, to and from the information terminal apparatus  1 . 
     When the communication apparatus  30  is not connected to the information terminal apparatus  1 , the type-identifying response  106  to the analyzing section  4  is not generated, and the signal line  55  connected to the analyzing section  4  continually provides a high level state by the action of the pull up resistor  551 . Further, since the polarity of signal input/output lines on the communication apparatus  30  is unknown, the control section  2  controls the switching section  7  by the switching control  108  so that the signal line  57  connected to the open collector type output buffer is connected to the signal line  58  connected to a terminal  804  on the connector. 
     The control section  2  periodically polls the analyzing section  4  by sending the analysis instruction  103  via the handling bus  53  to check the connection or non-connection of the communication apparatus  30 , and in response to the analysis instruction  103 , the analyzing section  4  outputs the type inquiry  104  onto the signal line  54 . When the communication apparatus  30  is not connected, the analyzing section  4  cannot obtain the type-identifying response  106  and, therefore, cannot report the state verification  105  within waiting time T 2 . The control section  2  thus automatically recognizes that the communication apparatus  30  is not connected. 
     When the communication apparatus  30  is connected, a terminal  802  on the connector  8  of the information terminal apparatus  1  is connected to a terminal  312  on the connector  31  of the communication apparatus  30 , and a terminal  803  on the connector  8  of the information terminal apparatus  1  is connected to a terminal  313  on the connector  31  of the communication apparatus  30 , so that the type inquiry  104  from the analyzing section  4  is delivered to the responding section  33  via the signal line  72  in the communication apparatus  30 . In response to the type inquiry  104 , the responding section  33  in the communication apparatus  30  sends out the type-identifying response  106  unique to the communication apparatus  30  onto the signal line  73  for transmission to the information terminal apparatus  1 . In the information terminal apparatus  1 , the received type-identifying response  106  is delivered to the analyzing section  4  via the signal line  55 . Upon receiving the type-identifying response  106 , the analyzing section  4  reports the result by sending the state verification  105  via the handling bus  53 . 
     FIG. 25 shows a flow chart for judging the type of the connected communication apparatus. In a communication apparatus verification process ( 6102 ) which is initiated by a periodic timer interrupt ( 6101 ), the control section performs processing to recognize the connection or non-connection of a communication apparatus and the type of the connected communication apparatus. When the communication apparatus verification ( 6001 ) is started, the control section issues an analysis instruction to the analyzing section ( 6002 ), and thereupon starts a timer to count the waiting time T 2  necessary for state verification ( 6003 ). In the next step ( 6004 ) it is determined whether the waiting time T 2  has elapsed or not. When the time T 2  has elapsed, the process exits the loop, and the T 2  timer is stopped ( 6005 ). Next, the analyzing section is instructed to verify the state ( 6006 ), and waits for a type-identifying response from the communication apparatus. When the communication apparatus is not connected, no report is made from the analyzing section; therefore, in the decision step ( 6007 ) it is decided that no state verification report is available, and the process proceeds to the next step ( 6008 ) where it is determined that no communication apparatus is connected, whereupon the process is terminated ( 6012 ). 
     If a communication apparatus A is connected which returns a type-identifying response A in response to the type inquiry, the analyzing section sends a report A in response to the state verification instruction from the control section. The process then follows the NO branch of the decision step ( 6007 ), and proceeds to the step ( 6009 ) where the YES branch is followed since the report verification report indicates A. In the next step ( 6010 ), it is determined that the communication apparatus A has been connected. In this way, the type of the connected communication apparatus can be identified from the type of the received response. 
     In FIG. 24, matching to the characteristics of the signal input/output sections of the communication apparatus  30  is done by recognizing the type of the connected communication apparatus  30  from the report obtained in response to the state verification  105 ; to achieve this, the control section  2  sends the switching control  108  to the switching section  7  so that control signals and data can be transferred between the information terminal apparatus  1  and the communication apparatus  30 . 
     In FIG. 24, the circuit block for transferring the control signals and data between the information terminal apparatus  1  and the communication apparatus is shown as having only one control path, but by providing a plurality of switching controls, an interface for transferring control signals and data using multiple paths can be achieved. When the communication apparatus is provided with a notifying section that sends the connected state and the attribute of the communication apparatus when the communication apparatus is connected to the information terminal apparatus  1 , as in the first embodiment, if the judging section of the first embodiment is provided in the information terminal apparatus  1 , polling by the analyzing section is not needed and the control section can immediately issue an inquiry about the type of the connected communication apparatus, since the connecting of the communication apparatus to the information terminal apparatus  1  and the attribute of the connected communication apparatus can be detected through the notifying section. 
     Embodiment 10 
     As shown in FIG. 26, in a 10th embodiment, an information terminal apparatus  1  comprises: a control section  2  for controlling an interface connecting between the information terminal apparatus  1  and communication apparatus  30 ; a test section  9  for producing a test output  111  to assist in identifying the type of the connected communication apparatus  30 ; a signal line  59  for sending a test instruction  110  from the control section  2  to the test section  9 ; a signal line  60  for sending the test output  111  from the test section  9  to the communication apparatus  30 ; an analyzing section  4  for judging the type of the connected communication apparatus  30 ; a signal line  54  for sending a type inquiry  104  from the analyzing section  4  to the communication apparatus  30 ; a signal line  55  for the analyzing section  4  to receive a type-identifying response  106  from the communication apparatus  30  in response to the type inquiry; a handling bus  53  for transferring an analysis instruction  103  and a state verification instruction  105  from the control section  2  to the analyzing section  4 ; an input buffer  5  and an output buffer  6  for transferring control signals and data to and from the communication apparatus  30 ; a switching section  7  for automatically switching between the input buffer  5  and the output buffer  6  in response to a switching control  108  that the control section  2  issues by judging the connection characteristics based on the result of the analysis of the communication apparatus  30 ; a signal line  58  for transferring input/output signals  107 , such as control signals and data, between the communication apparatus  30  and the switching section  7 ; a signal line  56  for transferring control signals and data from the switching section  7  to the control section  2  via the input buffer  5 ; a signal line  57  for transferring control signals and data from the control section  2  to the switching section  7  via the output buffer  6  of an open collector type; a connector  8  accommodating terminals for connecting the signal lines to the communication apparatus  30 ; and pull up resistors  551  and  561  for providing a high level state when nothing is connected to the respective input sections and for providing an input signal of a prescribed level to an output section of the communication apparatus  30  when in a connected condition. 
     The communication apparatus  30  comprises: a responding section  33  for generating the type-identifying response  106  identifying the type of the communication apparatus  30  in response to the type inquiry  104  and test output  111  from the information terminal apparatus  1 ; a signal line  72  for delivering the type inquiry from the information terminal apparatus  1  to the responding section  33 ; a signal line  74  for delivering the test output  111  from the information terminal apparatus  1  to the responding section  33 ; a signal line  73  for sending the type-identifying response  106  from the responding section  33  to the information terminal apparatus  1 ; and a signal input section (not shown) and a signal output section  34  for transferring input/output signals  107 , such as control signals and data, to and from the information terminal apparatus  1 . 
     When the communication apparatus  30  is not connected to the information terminal apparatus  1 , the type-identifying response  106  to the analyzing section  4  is not generated, and the signal line  55  connected to the analyzing section  4  continually provides a high level state by the action of the pull up resistor  551 . Further, since the polarity of signal input/output lines on the communication apparatus  30  is unknown, the control section  2  controls the switching section  7  by the switching control  108  so that the signal line  57  connected to the open collector type output buffer is connected to the signal line  58  connected to a terminal  804  on the connector. 
     To verify the connection of the communication apparatus  30 , the control section  2  issues the test instruction  110  to the test section  9  via the signal line  59 , and the test section  9  outputs a low state as the test output onto the signal line  60 . On the other hand, the control section  2  periodically polls the analyzing section  4  by sending the analysis instruction  103  via the handling bus  53  to check the connection or non-connection of the communication apparatus  30 , and in response to the analysis instruction  103 , the analyzing section  4  outputs the type inquiry  104  onto the signal line  54 . When the communication apparatus  30  is not connected, the analyzing section  4  receives a high state as the type-identifying response  106 , and the control section  2  thus automatically recognizes that the communication apparatus  30  is not connected. 
     When the communication apparatus  30  is connected, a terminal  802  on the connector  8  of the information terminal apparatus  1  is connected to a terminal  312  on the connector  31  of the communication apparatus  30 , a terminal  803  on the connector  8  of the information terminal apparatus  1  is connected to a terminal  313  on the connector  31  of the communication apparatus  30 , and a terminal  805  on the connector  8  of the information terminal apparatus  1  is connected to a terminal  315  on the connector  31  of the communication apparatus  30 , so that the type inquiry  104  from the analyzing section  4  and the test output  111  from the test section  9  are delivered to the responding section  33 , the former via the signal line  72  and the latter via the signal line  74  in the communication apparatus  30 . The responding section  33  provided in the communication apparatus  30  differs depending on the type of the communication apparatus, and returns the type-identifying response  106  unique to the type in response to the type inquiry from the analyzing section  4  when the test output  111  from the test section  9  is at a low level. 
     FIG. 27 shows a communication apparatus E, and FIG. 28 shows a communication apparatus F. In the case of the communication apparatus E, when the test output  111  is fixed at the low level, the type inquiry  104  sent from the analyzing section  4  to the responding section  33  is returned unchanged as the type-identifying response  106  to the analyzing section  4  in the information terminal apparatus  1 . In the case of the communication apparatus F, on the other hand, when the test output  111  is fixed at the low level, the responding section  4  returns a low level signal as the type-identifying response  106  to the analyzing section  4  in the information terminal apparatus  1 , regardless of the type inquiry  104  from the analyzing section  4 . 
     In FIG. 26, in the information terminal apparatus  1 , the returned type-identifying response  106  is delivered to the analyzing section  4  via the signal line  55 . Upon receiving the type-identifying response  106 , the analyzing section  4  reports the result in response to the state verification instruction  105  sent from the control section  2  via the handling bus  53 . 
     FIG. 29 shows a flow chart for judging the type of the connected communication apparatus. In a communication apparatus verification process ( 7102 ) which is initiated by a periodic timer interrupt ( 7101 ), the control section  2  performs processing to recognize the connection or non-connection of a communication apparatus and the type of the connected communication apparatus. When the communication apparatus verification ( 7001 ) is started, the control section  2  first issues an instruction to the test section  9  to output a test output L ( 7002 ), and then issues an analysis instruction to the analyzing section  4  ( 7003 ), which is followed by a state verification instruction ( 7004 ) to the analyzing section  4  to wait for a report of the type-identifying response from the communication apparatus  30 . When the communication apparatus  30  is not connected, since a high level H is returned as a state verification report from the analyzing section  4 , the state verification is H in the next evaluation step ( 7005 ), and it is determined in the next step ( 7006 ) that no communication apparatus is connected. 
     When the communication apparatus F shown in FIG. 28 is connected, the responding section  33  of the communication apparatus F, when the test output  111  is fixed at the low level, returns a type-identifying response by outputting a low level L in response to the type inquiry  104  from the analyzing section  4 ; as a consequence, the analyzing section  4  returns a report L in response to the state verification instruction from the control section  2 , so that the NO branch of the evaluation step ( 7005 ) is followed to proceed to the next evaluation step ( 7007 ). Since the state verification report is L in the evaluation step ( 7007 ), the process proceeds to the next step ( 7008 ) to determine that the communication apparatus F has been connected. On the other hand, when the communication apparatus E is connected, the responding section  33  of the communication apparatus E, when the test output  111  is fixed at the low level, returns the type inquiry  104 , received from the analyzing section  4 , unchanged as the type-identifying response  106  to the analyzing section  4  in the information terminal apparatus  1 ; as a consequence, the analyzing section  4  returns a report “type inquiry” in response to the state verification instruction from the control section  2 , so that the NO branch of the evaluation step ( 7005 ) is followed and also the NO branch of the evaluation step ( 7007 ) is followed to proceed to the next evaluation step ( 7009 ). Since the state verification is the type inquiry in the evaluation step ( 7009 ), it is determined that the communication apparatus E has been connected. In this example, any arbitrary type of communication apparatus can be identified by the type-identifying response returned from the communication apparatus. 
     In FIG. 26, matching to the characteristics of the signal input/output sections of the communication apparatus  30  is done by recognizing the type of the connected communication apparatus  30  from the report obtained in response to the state verification  105 ; to achieve this, the control section  2  sends the switching control  108  to the switching section  7  so that control signals and data can be transferred between the information terminal apparatus  1  and the communication apparatus  30 . 
     In FIG. 26, the circuit block for transferring the control signals and data between the information terminal apparatus  1  and the communication apparatus is shown as having only one control path, but by providing a plurality of switching controls, an interface for transferring control signals and data using multiple paths can be achieved. When the communication apparatus is provided with a notifying section that sends the connected state and the attribute of the communication apparatus when the communication apparatus is connected to the information terminal apparatus  1 , if the judging section of the first embodiment is provided in the information terminal apparatus  1 , polling by the analyzing section  4  is not needed and the control section  2  can immediately issue an inquiry about the type of the connected communication apparatus, since the connecting of the communication apparatus to the information terminal apparatus  1  and the attribute of the connected communication apparatus can be detected through the notifying section  4 . 
     Embodiment 11 
     As shown in FIG. 30, in an 11th embodiment, an information terminal apparatus  1  comprises: a control section  2  for controlling an interface connecting between the information terminal apparatus  1  and communication apparatus  30 ; a judging section  3 , connected to the control section  2 , for producing a report corresponding to a connection notification  102  received from the communication apparatus  30 ; a signal line  52  for the judging section  3  to receive the connection notification  102  from the communication apparatus  30 ; an interrupt line  51  for reporting a judgement result  101  from the judging section  3  to the control section  2 ; a test section  9  for producing a test output  111  to assist in identifying the type of the connected communication apparatus  30 ; a signal line  59  for sending a test instruction  110  from the control section  2  to the test section  9 ; a signal line  60  for sending the test output  111  from the test section  9  to the communication apparatus  30 ; a signal line  62  for the test section  9  to receive a test input  113  from the communication apparatus  30 ; a test report interrupt line  61  for sending a test report  112  from the test section  9  to the control section  2 ; an input buffer  5  and an output buffer  6  for the control section  2  to transfer control signals and data to and from the communication apparatus  30 ; a switching section  7  for automatically switching between the input buffer  5  and the output buffer  6  in response to a switching control  108  that the control section  2  issues by judging the connection characteristics based on the result of the test of the communication apparatus  30 ; a signal line  58  for transferring input/output signals  107 , such as control signals and data, between the communication apparatus  30  and the switching section  7 ; a signal line  56  for transferring control signals and data from the switching section  7  to the control section  2  via the input buffer  5 ; a signal line  57  for transferring control signals and data from the control section  2  to the switching section  7  via the output buffer  6  of an open collector type; a connector  8  accommodating terminals for connecting the signal lines to the communication apparatus  30 ; and pull up resistors  521 ,  561 , and  621  for providing a high level state when nothing is connected to the respective input sections and for providing an input signal of a prescribed level to an output section of the communication apparatus  30  when in a connected condition. 
     The communication apparatus  30  comprises: a responding section  33  for generating the test input  113  as a response of the communication apparatus  30  by receiving the test output  111  from the information terminal apparatus  1 ; a signal line  74  for delivering the test output  111  from the information terminal apparatus  1  to the responding section  33 ; a signal line  75  for sending the test input  113  from the responding section  33  to the information terminal apparatus  1 ; and a signal input section (not shown) and a signal output section  34  for transferring input/output signals  107 , such as control signals and data, to and from the information terminal apparatus  1 . 
     When the communication apparatus  30  is not connected to the information terminal apparatus  1 , since the polarity of signal input/output lines on the communication apparatus  30  is unknown, the control section  2  controls the switching section  7  by the switching control  108  so that the signal line  57  connected to the open collector type output buffer is connected to the signal line  58  connected to a terminal  804  on the connector. 
     Upon verifying the connection of the communication apparatus  30  through the judging section  3  in the same manner as the fourth embodiment, the control section  2  sends the test instruction  110  to the test section  9  via the signal line  59 , whereupon the test section  9  outputs a low level L as the test output  111  onto the signal line  60 . The responding section  33  provided in the communication apparatus  30  differs depending on the type of the communication apparatus, and returns the test input  113  unique to the type in response to the test output  111  from the test section  9 . 
     FIG. 31 shows a communication apparatus E, and FIG. 32 shows a communication apparatus F. In the responding section  33  of the communication apparatus E, if the test output  111  changes to L, there occurs no change in the test input  113  returned as a response; as a result, the test section  9  determines that there is no state change in response to the test output  111 , and sends the test report  112  to the control section  2  which then recognizes the connection of the communication apparatus E. On the other hand, in the responding section  33  of the communication apparatus F, when the test output  111  changes to L, a pulse occurs in the test input  113  due to capacitive coupling. This pulse is interpreted by the test section  9  as being a state change associated with the test output  111 , and the test section  9  sends the test report  112  to the control section  2  which then recognizes the connection of the communication apparatus F. 
     FIG. 33 shows a flow chart for judging the type of the connected communication apparatus. When the connection of the communication apparatus  30  is verified through the judging section  3 , the control section  2  initiates a communication apparatus verification process  8001 . First, the control section  2  issues a test instruction to the test section  9  ( 8002 ). In response, the test section  9  outputs a test output L. Next, the process proceeds to the test report checking step ( 8003 ) to receive a report of the test input from the communication apparatus  30 . 
     When the communication apparatus E shown in FIG. 31 is connected, since there occurs no change in the test input returned from the communication apparatus E as a response to the test output, it is determined that there is no state change ( 8004 ), and the process proceeds to the next step ( 8005 ) where it is determined that the communication apparatus E has been connected. On the other hand, when the communication apparatus F shown in FIG. 32 is connected, since the communication apparatus F responds to the test output by a pulse-like test input, the NO branch of the decision step ( 8004 ) is followed to proceed to the next step ( 8006 ) where it is determined that the communication apparatus F has been connected. In either case, the test output is returned to H ( 8007 ) to terminate the process, and I/F matching is performed ( 8008 ). 
     In FIG. 30, matching to the characteristics of the signal input/output sections of the communication apparatus  30  is done by recognizing the type of the connected communication apparatus  30  from the report obtained in response to the state verification  105 ; to achieve-this, the control section  2  sends the switching control  108  to the switching section  7  so that control signals and data can be transferred between the information terminal apparatus  1  and the communication apparatus  30 . 
     In FIG. 30, the circuit block for transferring the control signals and data between the information terminal apparatus  1  and the communication apparatus is shown as having only one control path, but by providing a plurality of switching controls, an interface for transferring control signals and data using multiple paths can be achieved. 
     Embodiment 12 
     As shown in FIG. 30, in a 12th embodiment, an information terminal apparatus  1  comprises: a control section  2  for controlling an interface connecting between the information terminal apparatus  1  and communication apparatus  30 ; a judging section  3 , connected to the control section  2 , for producing a report corresponding to a connection notification  102  received from the communication apparatus  30 ; a signal line  52  for the judging section  3  to receive the connection notification  102  from the communication apparatus  30 ; an interrupt line  51  for reporting a judgement result  101  from the judging section  3  to the control section  2 ; a test section  9  for producing a test output  111  to assist in identifying the type of the connected communication apparatus  30 ; a signal line  59  for sending a test instruction  110  from the control section  2  to the test section  9 ; a signal line  60  for sending the test output  111  from the test section  9  to the communication apparatus  30 ; a signal line  62  for the test section  9  to receive a test input  113  from the communication apparatus  30 ; a test report interrupt line  61  for sending a test report  112  from the test section  9  to the control section  2 ; an input buffer  5  and an output buffer  6  for the control section  2  to transfer control signals and data to and from the communication apparatus  30 ; a switching section  7  for automatically switching between the input buffer  5  and the output buffer  6  in response to a switching control  108  that the control section  2  issues by judging the connection characteristics based on the result of the test of the communication apparatus  30 ; a signal line  58  for transferring input/output signals  107 , such as control signals and data, between the communication apparatus  30  and the switching section  7 ; a signal line  56  for transferring control signals and data from the switching section  7  to the control section  2  via the input buffer  5 ; a signal line  57  for transferring control signals and data from the control section  2  to the switching section  7  via the output buffer  6  of an open collector type; a connector  8  accommodating terminals for connecting the signal lines to the communication apparatus  30 ; and pull up resistors  521 ,  561 , and  621  for providing a high level state when nothing is connected to the respective input sections and for providing an input signal of a prescribed level to an output section of the communication apparatus  30  when in a connected condition. 
     The communication apparatus  30  comprises: a responding section  33  for generating the test input  113  as a response of the communication apparatus  30  by receiving the test output  111  from the information terminal apparatus  1 ; a signal line  74  for delivering the test output  111  from the information terminal apparatus  1  to the responding section  33 ; a signal line  75  for sending the test input  113  from the responding section  33  to the information terminal apparatus  1 ; and a signal input section (not shown) and a signal output section  34  for transferring input/output signals  107 , such as control signals and data, to and from the information terminal apparatus  1 . 
     When the communication apparatus  30  is not connected to the information terminal apparatus  1 , since the polarity of signal input/output lines on the communication apparatus  30  is unknown, the control section  2  controls the switching section  7  by the switching control  108  so that the signal line  57  connected to the open collector type output buffer is connected to the signal line  58  connected to a terminal  804  on the connector. 
     When the beginning of the connection of the communication apparatus  30  is detected by receiving a connection notifying interrupt at the judging section  3 , the control section  2  sends the test instruction  110  to the test section  9  via the signal line  59 , whereupon the test section  9  outputs a low level L as the test output  111  onto the signal line  60 . In the communication apparatus  30 , since the test output  111  is looped back as the test input  113 , when the test output  111  of a low level L is delivered, a low level L is returned as the test input  113 . Here, the connector configuration is such that a time lag occurs between the time a type-identifying terminal, which differs according to the type of the communication apparatus  30 , is connected and the time a terminal  316  to which the test input  113  is coupled is connected to the corresponding terminal on the connector of the information terminal apparatus  1 , and the time lag can be varied according to the type of the communication apparatus. 
     FIG. 34 shows a communication apparatus G, and FIG. 35 shows a communication apparatus H. In the responding section  33  of the communication apparatus G, when the beginning of the connection of the communication apparatus G is detected by the judging section  3  of the information terminal apparatus  1 , and the low level L is output on the test output  111 , the low level L appears at the test input  113  with a delay of time Tg from the beginning of the connector connection. This gives rise to a test report interrupt which causes the test section  9  to send a test report to the control section  2 . In the responding section  33  of the communication apparatus H, on the other hand, when the beginning of the connection of the communication apparatus H is detected by the judging section  3  of the information terminal apparatus  1 , and the low level L is output on the test output  111 , the low level L appears at the test input  113  with a delay of time Th from the beginning of the connector connection. This gives rise to a test report interrupt which causes the test section  9  to send a test report to the control section  2 . 
     FIG. 36 shows a flow chart for judging the type of the connected communication apparatus. The judging process is carried out by making use of the value of time Tn necessary for connector connection from the time the connection notification interrupt is caused to the time the connection of the test input is completed. When the communication apparatus  30  is connected to the information terminal apparatus  1 , the connection notification interrupt occurs to initiate the processing sequence ( 9001 ). When the judging process is started, a connection notification interrupt disable step ( 9002 ) is carried out in order to prevent multiple occurrences of the connection notification interrupt during time T 1 . Next, the step of initializing the timer value Tn is carried out ( 9003 ). Then, after carrying out a test report interrupt enable step ( 9004 ), the process proceeds to the step ( 9005 ) to determine whether the time T 1  necessary for the connector connection has elapsed or not. When the test report interrupt enable step ( 9004 ) is carried out in the connection interrupt process, a test report interrupt process ( 9101 ) is initiated, and stops the timer Tn ( 9102 ) when the test report interrupt occurs; after that, the process is terminated ( 9103 ). When the waiting time T 1  necessary for the connector connection has elapsed in the connection interrupt process, a test report interrupt disable process ( 9006 ) is carried out to prevent an illegal test report interrupt from occurring after the time T 1  necessary for the connector connection has elapsed. Next, the process proceeds to the step ( 9007 ) of judging the attribute of the communication apparatus from the timer value obtained by the test report interrupt. 
     When the communication apparatus G of FIG. 34 is connected, since the control section  2  issues a test report interrupt after the time Tg following the connection notification interrupt, Tn=Tg in the evaluation step ( 9007 ) and it is determined in the next step ( 9008 ) that the communication apparatus G has been connected, after which the judging process is terminated. On the other hand, when the communication apparatus H of FIG. 35 is connected, since the judging section  3  issues a test report interrupt after the time Th following the connection notification interrupt, Tn is not Tg in the evaluation step ( 9007 ) and Tn=Th in the next evaluation step ( 9009 ); then, it is determined in the next step ( 9010 ) that the communication apparatus H has been connected, after which the judging process is terminated. In this embodiment, any arbitrary kind of attribute can be judged by suitably setting the time lag required to complete the connection of the test input terminal on the communication apparatus. 
     When the judging process is terminated, a connection notification interrupt enable step ( 9012 ) is carried out to enable the automatic judgement for the next communication apparatus to be connected. The whole process for judging the attribute of the connected communication apparatus is thus terminated, and I/F matching ( 9013 ) is performed. 
     In FIG. 30, matching to the characteristics of the signal input/output sections of the communication apparatus  30  is done by recognizing the type of the connected communication apparatus  30  from the report obtained in response to the state verification  105 ; to achieve this, the control section  2  sends the switching control  108  to the switching section  7  so that control signals and data can be transferred between the information terminal apparatus  1  and the communication apparatus  30 . 
     In FIG. 30, the circuit block for transferring the control signals and data between the information terminal apparatus  1  and the communication apparatus is shown as having only one control path, but by providing a plurality of switching controls, an interface for transferring control signals and data using multiple paths can be achieved. 
     Embodiment 13 
     FIG. 43 is a conceptual diagram showing the configuration for implementing the automatic signal switching operation of the invention, and FIG. 37 is a diagram illustrating one embodiment of a communication apparatus detection process. 
     With no communication apparatus  30  connected to the interface of the information terminal apparatus  1  ( 10001 ), when the communication apparatus  30  is connected to the connector of the information terminal apparatus  1 , an interrupt occurs from the judging section  3  by a signal change on the notification signal line, and the control section  2  notifies the test section  9  to activate the test output signal line ( 10002 ). After that, the control section  2  starts a timer T 1  and waits for an interrupt notification to occur from the test section  9  by a signal change on the test input signal line. 
     Suppose here that a communication apparatus A of speed A is connected. Since the communication apparatus A has a signal line control function by which the responding section  33  activates the test input signal line in response to the activation of the test output signal line from the information terminal apparatus  1 , the test section  9  detects the signal change on the test input signal line, and notifies the control section  2  by causing an interrupt. The control section  2  thus detects the connection of the communication apparatus A, stops the timer T 1 , and initializes the communication apparatus A ( 10004 ). 
     On the other hand, when a communication apparatus B of speed B is connected, the signal on the test input signal line does not change because the communication apparatus B does not have a signal line control function by which the responding section  33  activates the test input signal line in response to the activation of the test output signal line from the information terminal apparatus  1 . When the communication apparatus A in a power OFF state is connected, the signal on the test input signal line also remains unchanged. If an interrupt due to a signal change on the test input signal line does not occur from the test section  9  within the predetermined time T 1 , the control section  2  decides that the timer T 1  has timed out, and determines that the communication apparatus connected to the connector is either the communication apparatus B or the communication apparatus A in a power OFF state ( 10003 ). 
     By performing the above process sequence, the communication apparatus detection process for the automatic signal switching operation according to the 14th invention is accomplished. 
     Embodiment 14 
     FIG. 43 is a conceptual diagram showing the configuration for implementing the automatic signal switching operation according to the invention, and FIG. 37 is a diagram illustrating one embodiment of the communication apparatus detection process. 
     In the communication apparatus undetermined state ( 10003 ) in which the connected communication apparatus  30  is judged to be either the communication apparatus B or the communication apparatus A in a power OFF state, the control section  2  monitors an interrupt notification to occur by a signal change on the test input signal line while the timer T 1  used to wait for an interrupt notification to occur by a signal change on the test input signal line is held in the stopped condition. 
     Here, when the communication apparatus A changes from the power OFF to the power ON state, the responding section  33  of the communication apparatus activates the test input signal line; as a result, the control section  2  detects the connection of the communication apparatus A by the interrupt notification caused by the signal change on the test input signal line, and initializes the communication apparatus A ( 10004 ). If the initialization procedure failed, a communication apparatus recognition failure notification is issued, and the process is terminated ( 10005 ). 
     When the initialization procedure is successfully accomplished, the control section  2  switches to communication apparatus A operation mode, and notifies the switching section  7  to switch the input/output lines to the communication apparatus A mode ( 10007 ). Thereafter, when a call request is received from an application, a call origination procedure is performed to connect the call with speed A ( 10010 ). 
     On the other hand, in the communication apparatus undetermined state ( 10003 ), when a call request is received from an application, the control section  2  switches to communication apparatus B operation mode, and notifies the switching section  7  to switch the input/output lines to the communication apparatus B mode ( 10006 ). Then, a call origination procedure is tried with speed B, and if the procedure is successfully accomplished, a normal call is originated ( 10008 ). 
     If the procedure failed, on the other hand, it can be determined that the communication apparatus  30  is in the power OFF state, and a communication apparatus recognition failure is notified ( 10009 ). 
     By performing the above process sequence, the communication apparatus detection process for the automatic signal switching operation according to the 15th invention is accomplished. 
     Embodiment 15 
     FIG. 43 is a conceptual diagram showing the configuration for implementing the automatic signal switching operation according to the invention, and FIG. 38 is a diagram illustrating one embodiment of the communication apparatus detection process. 
     With no communication apparatus  30  connected to the interface of the information terminal apparatus  1  ( 10101 ), when the communication apparatus  30  is connected to the connector of the information terminal apparatus  1 , an interrupt occurs from the judging section  3  by a signal change on the notification signal line, and the control section  2  makes a transition to the communication apparatus undetermined state in which the communication apparatus  30  is not yet recognized ( 10102 ). When a call request is received from an application, the control section  2  notifies the test section  9  to active the test output signal line ( 10103 ). After that, the control section  2  starts the timer T 1  and waits for an interrupt notification to occur from the test section  9  by a signal change on the test input signal line. 
     Suppose here that a communication apparatus A of speed A is connected. Since the communication apparatus A has a signal line control function by which the responding section  33  activates the test input signal line in response to the activation of the test output signal line from the information terminal apparatus  1 , the test section  9  detects the signal change on the test input signal line, and notifies the control section  2  by causing an interrupt. The control section  2  thus detects the connection of the communication apparatus A, stops the timer T 1 , and initializes the communication apparatus A ( 10104 ). If the initialization procedure failed, a communication apparatus recognition failure notification is issued, and the process is terminated ( 10105 ). 
     When the initialization procedure is successfully accomplished, the control section  2  switches to communication apparatus A operation mode, and notifies the switching section  7  to switch the input/output lines to the communication apparatus A mode ( 10107 ). Thereafter, when a call request is received from the application, a call origination procedure is performed to accomplish the call origination with speed A ( 10110 ). 
     On the other hand, when a communication apparatus B of speed B is connected, the signal on the test input signal line does not change because the communication apparatus B does not have a signal line control function by which the responding section  33  activates the test input signal line in response to the activation of the test output signal line from the information terminal apparatus  1 . When the communication apparatus A in a power OFF state is connected, the signal on the test input signal line also remains unchanged. If an interrupt due to a signal change on the test input signal line does not occur from the test section  9  within the predetermined time T 1 , the control section  2  decides that the timer T 1  has timed out, and determines that the communication apparatus  30  connected to the connector is either the communication apparatus B or the communication apparatus A in a power OFF state. The control section  2  then switches to communication apparatus B operation mode, and notifies the switching section  7  to switch the input/output lines to the communication apparatus B mode ( 10106 ). Then, a call origination procedure is tried with speed B, and if the procedure is successfully accomplished, a normal call is established ( 10108 ). If the procedure failed, on the other hand, it can be determined that the communication apparatus is in the power OFF state, and a communication apparatus recognition failure notification is issued ( 10109 ). By performing the above process sequence, the communication apparatus detection process for the automatic signal switching operation according to the 16th invention is accomplished. 
     Embodiment 16 
     FIG. 43 is a conceptual diagram showing the configuration for implementing the automatic signal switching operation according to the invention, and FIG. 39 is a diagram illustrating one embodiment of the communication apparatus detection process. 
     With no communication apparatus  30  connected to the interface of the information terminal apparatus  1  ( 10201 ), when the communication apparatus  30  is connected to the connector of the information terminal apparatus  1 , an interrupt occurs from the judging section  3  by a signal change on the notification signal line, and the control section  2  makes a transition to the communication apparatus undetermined state in which the communication apparatus  30  is not yet recognized ( 10202 ). When a call request is received from an application, the control section  2  instructs the test section  9  to try a call origination procedure with communication speed A ( 10203 ). If the call origination procedure succeeds, the control section  2  switches to communication apparatus A operation mode, notifies the switching section  7  to switch the input/output lines to the communication apparatus A mode ( 10205 ), and accomplishes the call origination with speed A ( 10212 ). If the call origination with communication speed A failed, then the control section  2  instructs the test section  9  to try the call origination procedure with a different communication speed B ( 10204 ). If the call origination procedure succeeds, the control section  2  switches to communication apparatus B operation mode, notifies the switching section  7  to switch the input/output lines to the communication apparatus B mode ( 10207 ), and accomplishes the call origination with speed B ( 10211 ). If failed, the call origination procedure is tried with different communication speeds N one after another ( 10206 ). 
     If the call origination procedure succeeds, the control section  2  switches to communication apparatus N operation mode, notifies the switching section  7  to switch the input/output lines to the communication apparatus N mode ( 10208 ), and accomplishes the call origination with speed N ( 10210 ). If the call origination procedure failed after trying with all communication speeds, a communication apparatus recognition failure is notified ( 10209 ). By performing the above process sequence, the communication apparatus detection process for the automatic signal switching operation according to the 17th invention is accomplished. 
     Embodiment 17 
     FIG. 43 is a conceptual diagram showing the configuration for implementing the automatic signal switching operation according to the invention, and FIG. 40 is a diagram illustrating one embodiment of the communication apparatus detection process. 
     With no communication apparatus  30  connected to the interface of the information terminal apparatus  1  ( 10301 ), when the communication apparatus  30  is connected to the connector of the information terminal apparatus  1 , an interrupt occurs from the judging section  3  by a signal change on the notification signal line, and the control section  2  notifies the test section  9  to activate the test output signal line ( 10302 ). Thereafter, the control section  2  makes a transition to the communication apparatus undetermined state ( 10303 ) to wait for an interrupt notification to occur from the test section  9  by a signal change on the test input signal line or for an interrupt notification to occur by the reception of data on the response signal line from the communication apparatus  30  of speed B. Here, if a call arrives at a communication apparatus A of speed A, the responding section  33  of the communication apparatus A activates the test input signal line; the test section  9  then detects the signal change on the test input signal line and notifies the control section  2  by causing an interrupt. The control section  2  thus detects the connection of the communication apparatus A, and performs a call termination procedure of the communication apparatus A ( 10305 ). 
     If the call termination procedure failed, the control section  2  makes a transition back to the communication apparatus undetermined state ( 10303 ); on the other hand, when the call termination procedure is successfully accomplished, the control section  2  switches to the communication apparatus A operation mode, notifies the switching section  7  to switch the input/output lines to the communication apparatus A mode ( 10307 ), and accomplishes the call termination with speed A ( 10309 ). If a call arrives at a communication apparatus B of speed B, the responding section  33  of the communication apparatus B sends data onto the response signal line indicating the arrival of a call with speed B; when any data is received on the response signal line, the test section  9  notifies the control section  2  of an interrupt, and the control section  2  thus detects the connection of the communication apparatus B and performs a call termination procedure of the communication apparatus B ( 10304 ). When the call arrival indicating data received from the response signal line is recognized by the control section  2 , if the call termination procedure failed, the control section  2  makes a transition back to the communication apparatus undetermined state ( 10303 ); on the other hand, if the call termination procedure is successfully accomplished, the control section  2  switches to the communication apparatus B operation mode, notifies the switching section  7  to switch the input/output lines to the communication apparatus B mode ( 10306 ), and accomplishes the call termination with speed B ( 10308 ). By performing the above process sequence, the communication apparatus detection process for the automatic signal switching operation according to the 18th invention is accomplished. 
     Embodiment 18 
     FIG. 43 is a conceptual diagram showing the configuration for implementing the automatic signal switching operation according to the invention, and FIG. 41 is a diagram illustrating one embodiment of the communication apparatus detection process. 
     With no communication apparatus  30  connected to the interface of the information terminal apparatus  1  ( 10401 ), when the communication apparatus  30  is connected to the connector of the information terminal apparatus  1 , an interrupt occurs from the judging section  3  by a signal change on the notification signal line, and the control section  2  notifies the test section  9  to activate the test output signal line ( 10402 ). Thereafter, the control section  2  makes a transition to the communication apparatus undetermined state ( 10403 ) to wait for an interrupt notification to occur from the test section  9  by a signal change on the test input signal line or for an interrupt notification to occur by the reception of data on the response signal line from the communication apparatus  30  of speed B. 
     Here, if a call arrives at a communication apparatus A of speed A, the responding section  33  of the communication apparatus A activates the test input signal line; the test section  9  then detects the signal change on the test input signal line and notifies the control section  2  by causing an interrupt. The control section  2  thus detects the connection of the communication apparatus A, and performs a call termination procedure of the communication apparatus A ( 10405 ). If the call termination procedure failed, the control section  2  makes a transition back to the communication apparatus undetermined state ( 10403 ); on the other hand, when the call termination procedure is successfully accomplished, the control section  2  switches to the communication apparatus A operation mode, notifies the switching section  7  to switch the input/output lines to the communication apparatus A mode ( 10408 ), and accomplishes the call termination with speed A ( 10410 ). If a call arrives at a communication apparatus B of speed B, the responding section  33  of the communication apparatus B outputs data indicating the arrival of a call with speed B onto the response signal line; therefore, only when predetermined specific data is received on the response signal line, the test section  9  notifies the control section  2  of an interrupt, and the control section  2  thus detects the connection of the communication apparatus B and performs a call termination procedure of the communication apparatus B ( 10404 ). 
     If the call termination procedure failed, the control section  2  clears the received data on the response signal line and resets the state ( 1406 ), and makes a transition back to the communication apparatus undetermined state ( 10403 ); on the other hand, when the call termination procedure is successfully accomplished, the control section  2  switches to the communication apparatus B operation mode, notifies the switching section  7  to switch the input/output lines to the communication apparatus B mode ( 10406 ), and accomplishes the call termination with speed B ( 10408 ). 
     By performing the above process sequence, the communication apparatus detection process for the automatic signal switching operation according to the 19th invention is accomplished. 
     Embodiment 19 
     FIG. 43 is a conceptual diagram showing the configuration for implementing the automatic signal switching operation according to the invention, and FIG. 42 is a diagram illustrating one embodiment of the communication apparatus detection process. 
     With no communication apparatus  30  connected to the interface of the information terminal apparatus  1  ( 10501 ), when the communication apparatus  30  is connected to the connector of the information terminal apparatus  1 , an interrupt occurs from the judging section  3  by a signal change on the notification signal line, and the control section  2  sets in the test section  9  a pattern used to detect the reception of data of a specific pattern from a response terminal ( 10502 ), and notifies the test section  9  to activate the test output signal line ( 10503 ). Thereafter, the control section  2  makes a transition to the communication apparatus undetermined state ( 10504 ) to wait for an interrupt notification to occur from the test section  9  by a signal change on the test input signal line or for an interrupt notification to occur by the reception of data on the response signal line from the communication apparatus  30  of speed B. 
     Here, if a call arrives at a communication apparatus A of speed A, the responding section  33  of the communication apparatus A activates the test input signal line; the test section  9  then detects the signal change on the test input signal line and notifies the control section  2  by causing an interrupt. The control section  2  thus detects the connection of the communication apparatus A, and performs a call termination procedure of the communication apparatus A ( 10506 ). If the call termination procedure failed, the control section  2  makes a transition back to the communication apparatus undetermined state ( 10504 ); on the other hand, when the call termination procedure is successfully accomplished, the control section  2  switches to the communication apparatus A operation mode, notifies the switching section  7  to switch the input/output lines to the communication apparatus A mode ( 10509 ), and accomplishes the call termination with speed A ( 10511 ). 
     If a call arrives at a communication apparatus B of speed B, the responding section  33  of the communication apparatus B outputs data indicating the arrival of a call with speed B onto the response signal line; therefore, only when the data that matches the pattern preset by the control section  2  is received on the response signal line, the test section  9  notifies the control section  2  of an interrupt, and the control section  2  thus detects the connection of the communication apparatus B and performs a call termination procedure of the communication apparatus B ( 10505 ). If the call termination procedure failed, the control section  2  resets the response signal line receive data pattern in the test section  9  ( 10507 ), and makes a transition back to the communication apparatus undetermined state ( 10504 ); on the other hand, when the call termination procedure is successfully accomplished, the control section  2  switches to the communication apparatus B operation mode, notifies the switching section  7  to switch the input/output lines to the communication apparatus B mode ( 10508 ), and accomplishes the call termination with speed B ( 10510 ). By performing the above process sequence, the communication apparatus detection process for the automatic signal switching operation according to the 20th invention is accomplished. 
     Embodiment 20 
     The automatic signal switching operation for automatically switching signal potentials, the input/output method of the interface, etc. by automatically detecting the connection of communication apparatus  30  and the attribute of the connected communication apparatus  30 , according to a 20th embodiment, is implemented in the same manner as in any one of the first to 19th embodiments, and the description of the operation will not be repeated here. 
     Referring to FIGS. 44,  45 , and  49 , a description will be given of an automatic signal switching operation in which when a communication application is started after automatically identifying the connected communication apparatus  30 , a call is automatically originated and the connection is set up in accordance with a communication procedure appropriate to the connected communication apparatus  30 . 
     FIG. 44 is a diagram showing the configuration of the information terminal apparatus  1  and communication apparatus  30  for implementing the 20th embodiment, and FIG. 45 is a connection destination information table  10   a  stored in a storage section  10  for various communication apparatuses  30  connectable to the information terminal apparatus  1 . 
     In FIG. 49, after a notification is provided from the judging section  3  identifying the communication apparatus  30  as a communication apparatus A, when a connection request for communication is received from the application ( 12001 ) the control section  2  retrieves connection destination telephone number A, connection ID A, and connection setup information A as the connection destination information for the communication apparatus  30  shown in FIG. 45 from the storage section  10  ( 12002 ), and using the retrieved information, a communication section  14  performs a call origination procedure ( 12003 ). The call is made to the destination via a communication section  36  in the communication apparatus  30 , and if the communication section  14  does not receive an answer from the destination within a predetermined time ( 12004 ), a destination no answer error is reported to the application ( 12008 ). 
     If there is an answer from the destination, the communication section  14  performs a communication connection procedure ( 12005 ); when the connection is successfully set up, the application is notified of connection completion ( 12007 ), but when the connection failed, the application is notified of a connection failed error ( 12008 ). 
     By performing the above process sequence, the automatic connection process of the 21st invention is accomplished. 
     Embodiment 21 
     Referring to FIGS. 44,  45 , and  50 , a description will be given of an automatic signal switching operation in which after a communication apparatus  30  is connected, and the connected communication apparatus  30  is automatically recognized, a call is automatically originated and the connection is set up in accordance with a communication procedure appropriate to the connected communication apparatus  30 . 
     FIG. 44 is a diagram showing the configuration of the information terminal apparatus  1  and communication apparatus  30  for implementing the 21st embodiment, and FIG. 45 shows the connection destination information table  10   a  stored in the storage section  10  for various communication apparatuses  30  connectable to the information terminal apparatus  1 . 
     In FIG. 50, after the communication apparatus  30  is connected to the information terminal apparatus  1 , and a notification is provided from the judging section  3  identifying the communication apparatus  30  as a communication apparatus A ( 13001 ), the control section  2  retrieves connection destination telephone number A, connection ID A, and connection setup information A as the connection destination information for the communication apparatus  30  shown in FIG. 45 from the storage section  10  ( 13002 ), and using the retrieved information, the communication section  14  performs a call origination procedure ( 13003 ). The call is made to the destination via the communication section  36  of the communication apparatus  30 , and if the communication section  14  does not receive an answer from the destination within a predetermined time ( 13004 ), a destination no answer error is reported to the application ( 13008 ). 
     If there is an answer from the destination, the communication section  14  performs a communication connection procedure ( 13005 ); when the connection is successfully set up, the application is notified of connection completion ( 13007 ), but when the connection failed, the application is notified of a connection failed error ( 13008 ). 
     Thereafter, the communication application is activated by the connection completion notification, thus starting data communication. 
     By performing the above process sequence, the automatic connection process of the 22nd invention is accomplished. 
     Embodiment 22 
     Referring to FIGS. 44,  45 , and  51 , a description will be given of an automatic signal switching operation in which when a communication apparatus  30  is connected to the information terminal apparatus  1  placed in an inactive state such as a sleep mode, the information terminal apparatus  1  enters an active state and automatically recognizes the connected communication apparatus  30 , and then a call is automatically originated and the connection is set up in accordance with a communication procedure appropriate to the connected communication apparatus  30 . 
     FIG. 44 is a diagram showing the configuration of the information terminal apparatus  1  and communication apparatus  30  for implementing the 22nd embodiment, and FIG. 45 shows the connection destination information table  10   a  stored in the storage section  10  for various communication apparatuses  30  connectable to the information terminal apparatus  1 . 
     In FIG. 51, the information terminal apparatus  1  is placed in an inactive state in which all processing sections, except the judging section  3  for detecting the attribute of the communication apparatus  30 , are deactivated; in this state, when the communication apparatus  30  is connected, the judging section  3  judges the attribute of the communication apparatus  30  and notifies the control section  2  ( 14001 ), thereby activating the information terminal apparatus  1  ( 14009 ). Recognizing the connection of the communication apparatus A, the control section  2  retrieves connection destination telephone number A, connection ID A, and connection setup information A as the connection destination information for the communication apparatus  30  shown in FIG. 45 from the storage section  10  ( 14002 ), and using the retrieved information, the communication section  14  performs a call origination procedure ( 14003 ). The call is made to the destination via the communication section  36  of the communication apparatus  30 , and if the communication section  14  does not receive an answer from the destination within a predetermined time ( 14004 ), a destination no answer error is reported to the application ( 14008 ). 
     If there is an answer from the destination, the communication section  14  performs a communication connection procedure ( 14005 ); when the connection is successfully set up, the application is notified of connection completion ( 14007 ), but when the connection failed, the application is notified of a connection failed error ( 14008 ). 
     Thereafter, the communication application is activated by the connection completion notification, thus starting data communication. 
     By performing the above process sequence, the automatic connection process of the 23rd invention is accomplished. 
     Embodiment 23 
     Referring to FIGS. 44,  46 , and  52 , a description will be given of an automatic signal switching operation in which when a communication application is started after automatically recognizing the connected communication apparatus  30 , a notification is issued recommending switching to a communication apparatus  30  that provides shorter communication time. 
     FIG. 44 is a diagram showing the configuration of the information terminal apparatus  1  and communication apparatus  30  for implementing the 23rd embodiment, and FIG. 46 shows a characteristic information table  10   b  stored in the storage section  10  for various communication apparatuses  30  connectable to the information terminal apparatus  1 . 
     In FIG. 52, after a notification is provided from the judging section  3  identifying the communication apparatus  30  as a communication apparatus A, when a connection request for communication is received from the application ( 15001 ) the control section  2  retrieves, from the storage section  10 , transmission speeds A to N and communication protocols A to N as the characteristic information for the communication apparatus  30  shown in FIG. 46 ( 15002 ), and using the retrieved information, the amount of data predicted to occur from the start to the end of the communication, and the communication procedure to be used, an arithmetic section  13  calculates communication times A to N for the respective communication apparatuses ( 15003 ). When comparisons are made between the predicted communication times A to N calculated by the arithmetic section  13  for the communication apparatuses A to N ( 15004 ), if there is no communication apparatus that provides a shorter communication time than the communication time A of the currently connected communication apparatus A ( 15005 ), the communication section  14  originates a call using the currently connected communication apparatus ( 15009 ). 
     On the other hand, if a communication apparatus B is detected as having a shorter communication time B than the communication time A of the currently connected communication apparatus A, a notification is sent to a display section  11  to display a notification recommending replacing the communication apparatus ( 15006 ), and the display section  11  displays on an LED or liquid crystal panel the communication time A of the currently connected communication apparatus A and the communication time B of the communication apparatus B recommended as a replacement along with a notification recommending removing the communication apparatus A and instead connecting the communication apparatus B ( 15007 ). Thereafter, the control section  2  of the information terminal apparatus  1  makes a transition to a state ( 15008 ) ready for detecting the replacement of the communication apparatus and the issuance of a call origination request from the application. 
     By performing the above process sequence, the notification process for recommending an optimum communication apparatus according to the 24th invention is accomplished. 
     Embodiment 24 
     Referring to FIGS. 44,  46 , and  53 , a description will be given of an automatic signal switching operation in which when a communication application is started after automatically recognizing the connected communication apparatus  30 , a notification is issued recommending switching to a communication apparatus  30  that provides shorter communication time. 
     FIG. 44 is a diagram showing the configuration of the information terminal apparatus  1  and communication apparatus  30  for implementing the 24th embodiment, and FIG. 46 shows the characteristic information table  10   b  stored in the storage section  10  for various communication apparatuses  30  connectable to the information terminal apparatus  1 . 
     The difference from the 23rd embodiment is that in FIG. 53, when a communication apparatus B is detected as having a shorter communication time B than the communication time A of the currently connected communication apparatus A ( 15005 ), a notification is sent to an audio output section  12  to produce an indication recommending replacing the communication apparatus ( 15006 ); using a buzzer or synthesized voice, the audio output section  12  audibly outputs information relating to the communication time A of the currently connected communication apparatus A and to the communication apparatus B recommended as a replacement and its communication time B along with information recommending removing the communication apparatus A and instead connecting the communication apparatus B ( 15010 ). Thereafter, the control section  2  of the information terminal apparatus  1  makes a transition to a state ( 15008 ) ready for detecting the replacement of the communication apparatus and the issuance of a call origination request from the application. 
     By performing the above process sequence, the notification process for recommending an optimum communication apparatus according to the 24th invention is accomplished. 
     Embodiment 25 
     Referring to FIGS. 44,  46 ,  47 , and  54 , a description will be given of an automatic signal switching operation in which when a communication application is started after automatically recognizing the connected communication apparatus  30 , a notification is issued recommending switching to a communication apparatus  30  with a lower communication charge. 
     FIG. 44 is a diagram showing the configuration of the information terminal apparatus  1  and communication apparatus  30  for implementing the 25th embodiment, FIG. 46 shows the characteristic information table  10   b  stored in the storage section  10  for various communication apparatuses  30  connectable to the information terminal apparatus  1 , and FIG. 47 is a tariff information table  10   c  stored in the storage section  10  for the various communication apparatuses  30 . 
     In FIG. 54, after a notification is provided from the judging section  3  identifying the communication apparatus  30  as a communication apparatus A, when a connection request for communication is received from the application ( 16001 ) the control section  2  retrieves, from the storage section  10 , transmission speeds A to N and communication protocols A to N shown in FIG. 46 as the characteristic information for the respective communication apparatuses  30  along with the tariff information shown in FIG. 47 for the respective communication apparatuses  30  ( 16002 ), and using the retrieved information, the amount of data and the number of packets predicted to occur from the start to the end of the communication, and the communication procedure to be used, the arithmetic section  13  calculates communication times A to N and communication charges A to N for the respective communication apparatuses ( 16003 ). When comparisons are made between the communication charges A to N calculated by the arithmetic section  13  for the communication apparatuses A to N ( 16004 ), if there is no communication apparatus with a lower communication charge than the communication charge A of the currently connected communication apparatus A ( 16005 ), the communication section  14  originates a call using the currently connected communication apparatus ( 16009 ). 
     On the other hand, if a communication apparatus B is detected as having a lower communication charge B than the communication charge A of the currently connected communication apparatus A, a notification is sent to the display section  11  or the audio output section  12  to output a notification recommending replacing the communication apparatus ( 16006 ), and the display section  11  or the audio output section  12  outputs the communication time A and communication charge A of the currently connected communication apparatus A and the communication time B and communication charge B of the communication apparatus B recommended as a replacement along with a notification recommending removing the communication apparatus A and instead connecting the communication apparatus B ( 16007 ). Thereafter, the control section  2  of the information terminal apparatus  1  makes a transition to a state ( 16008 ) ready for detecting the replacement of the communication apparatus and the issuance of a call origination request from the application. 
     By performing the above process sequence, the notification process for recommending an optimum communication apparatus according to the 25th invention is accomplished. 
     Embodiment 26 
     Referring to FIGS. 44,  48 , and  55 , a description will be given of an automatic signal switching operation in which when a communication application is started after automatically recognizing the connected communication apparatus  30 , the communication line condition is detected and a notification is issued recommending switching to a communication apparatus  30  having a wider communication area. 
     FIG. 44 is a diagram showing the configuration of the information terminal apparatus  1  and communication apparatus  30  for implementing the 26th embodiment, and FIG. 48 shows a supported communication area information table  10   d  stored in the storage section  10  for various communication apparatuses  30  connectable to the information terminal apparatus  1 . 
     In FIG. 55, after a notification is provided from the judging section  3  identifying the communication apparatus  30  as a communication apparatus A, when a connection request for communication is received from the application ( 17001 ) the communication section  14  collects communication line condition information such as current radio wave conditions, etc. from the communication section  36  of the communication apparatus  30  ( 17002 ), and if the control section  2  judges that the line condition is good from the communication line condition information obtained from the communication section  14  ( 17003 ), the communication section  14  originates a call using the currently connected communication apparatus ( 17006 ). 
     On the other hand, if the line condition is judged to be bad ( 17003 ), the control section  2  retrieves from the storage section  10  the supported communication area information for the respective communication apparatuses  30  shown in FIG. 48 ( 17004 ) and compares the supported area information between the respective communication apparatuses A to N ( 17005 ); if a communication apparatus B and a communication apparatus N are detected as having wider areas than area  1  and area  2  supported by the communication apparatus A ( 17007 ), a notification is sent to the display section  11  or the audio output section  12  to output a notification recommending replacing the communication apparatus ( 17008 ), and the display section  11  or the audio output section  12  outputs information relating to the currently connected communication apparatus A as well as the communication apparatus B and communication apparatus N recommended as a replacement along with a notification recommending removing the communication apparatus A and instead connecting the communication apparatus B or communication apparatus N ( 17009 ). Thereafter, the control section  2  of the information terminal apparatus  1  makes a transition to a state ( 17010 ) ready for detecting the replacement of the communication apparatus and the issuance of a call origination request from the application. 
     If there is no communication apparatus having a wider communication area than the communication area supported by the currently connected communication apparatus A ( 17007 ), the application is notified of a communication line condition deteriorated error ( 17011 ). 
     By performing the above process,sequence, the notification process for recommending an optimum communication apparatus according to the 26th invention is accomplished. 
     Embodiment 27 
     Referring to FIGS. 44,  45 ,  48 ,  56  and  57 , a description will be given of an automatic signal switching operation in which when communication is interrupted because of the deterioration of the communication line condition during data communication, a notification is issued recommending switching to a communication apparatus  30  having a wider communication area, while allowing the communication to be temporarily suspended during the replacement of communication apparatus  30  and to be resumed upon the completion of the replacement. 
     FIG. 44 is a diagram showing the configuration of the information terminal apparatus  1  and communication apparatus  30  for implementing the 27th embodiment, FIG. 45 shows the connection destination information table  10   a  stored in the storage section  10  for various communication apparatuses  30  connectable to the information terminal apparatus  1 , and FIG. 48 shows the supported communication area information table  10   d  stored in the storage section  10  for the various communication apparatuses  30 . 
     In FIG. 56, during data communication ( 18001 ) the communication section  14  continually monitors the line condition by collecting communication line condition information such as current radio wave conditions, etc. from the communication section  36  of the communication apparatus  30  ( 18002 ), and if the control section  2  judges that the line condition is good from the communication line condition information obtained from the communication section  14  ( 18003 ), the data communication is continued ( 18001 ); on the other hand, if the line condition is judged to be bad ( 18003 ), the control section  2  retrieves from the storage section  10  the supported communication area information for the respective communication apparatuses  30  shown in FIG. 48 ( 18004 ) and compares the supported area information between the respective communication apparatuses A to N ( 18005 ); if a communication apparatus B and a communication apparatus N are detected as having wider areas than area  1  and area  2  supported by the communication apparatus A ( 18006 ), the data communication is temporarily suspended and the suspended communication state is stored in the storage section  10  ( 18007 ). Thereafter, a notification is sent to the display section  11  or the audio output section  12  to output a notification recommending replacing the communication apparatus ( 18008 ), and the display section  11  or the audio output section  12  outputs information relating to the communication apparatus B and communication apparatus N recommended as a replacement along with a notification recommending removing the communication apparatus A and instead connecting the communication apparatus B or communication apparatus N ( 18009 ). Thereafter, the control section  2  of the information terminal apparatus  1  makes a transition to a state ( 18010 ) ready for detecting the replacement of the communication apparatus. 
     If there is no communication apparatus having a wider communication area than the communication area supported by the currently connected communication apparatus A ( 18006 ), the application is notified of a communication line condition deteriorated error ( 18011 ). 
     Further, in FIG. 57, when a transition is made to the state ready for detecting the replacement of the communication apparatus  30 , a timer for connection detection is started, and if the connection of a new communication apparatus  30  is not detected ( 18020 ), it is checked whether connection detection timeout has occurred or not ( 18023 ); if the timeout has not occurred, the state remains waiting for the detection of the replacement of the communication apparatus  30  ( 18010 ). 
     If the connection detection timeout has occurred ( 18023 ), a timeout error is reported to the application ( 18027 ). 
     When the connection of a new communication apparatus B is detected ( 18020 ), the control section  2  retrieves from the storage section  10  the destination telephone number B, connection ID B, and connection setup information B as the connection destination information for the communication apparatus  30  shown in FIG. 45 ( 18021 ), and using the retrieved information, the communication section  14  performs a call origination procedure ( 18022 ). The call is made to the destination via the communication section  36  of the communication apparatus  30 , and when the connection is set up successfully ( 18024 ), the suspended communication state is retrieved from the storage section  10  ( 18025 ), and the data communication is resumed from the point at which it was suspended ( 18025 ). 
     If the connection failed, the application is notified of a connection failed error ( 18027 ). 
     By performing the above process sequence, the notification process for recommending an optimum communication apparatus and the process for temporarily suspending and then resuming communications at the time of the replacement of communication apparatus, according to the 27th invention, are accomplished. 
     Embodiment 28 
     Referring to FIGS. 44,  48 ,  57  and  58 , a description will be given of an automatic signal switching operation for accomplishing temporary suspension and resumption of communication at the time of the replacement of communication apparatus  30  during data communication. 
     FIG. 44 is a diagram showing the configuration of the information terminal apparatus  1  and communication apparatus  30  for implementing the 28th embodiment, and FIG. 45 shows the connection destination information table  10   a  stored in the storage section  10  for various communication apparatuses.  30  connectable to the information terminal apparatus  1 . 
     In FIG. 58, during data communication ( 19001 ) the judging section  3  continually monitors the connected state of the communication apparatus  30 ; if the judging section  3  detects that the currently connected communication apparatus  30  is disconnected ( 19002 ), the data communication is temporarily suspended and the suspended communication state is stored in the storage section  10  ( 19003 ). Thereafter, the display section  11  or the audio output section  12  is notified of the disconnection of the communication apparatus ( 19004 ), and the display section  11  or the audio output section  12  outputs a notification recommending reconnecting the communication apparatus  30  ( 19005 ). Thereafter, the control section  2  of the information terminal apparatus  1  makes a transition to a state ( 19006 ) ready for detecting the replacement of the communication apparatus. 
     The remainder of the process is the same as that described in the 27th embodiment with reference to FIG.  57 . 
     By performing the above process sequence, the process for temporarily suspending and then resuming communications at the time of the replacement of communication apparatus, according to the 28th invention, is accomplished. 
     The invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. The present embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description and all changes which come within the meaning and the range of equivalency of the claims are therefore intended to be embraced therein.