now referring to the drawings , preferred embodiments of the invention are described below . fig1 is a block diagram that shows the electrical construction of a communication apparatus 20 , in which one example of the invention , the receiver 11 , is used . the transmitter 1 , which is carried by someone such as the driver , includes and is composed of an antenna 2 , a transmitting circuit 3 , a push button switch 4 , and a read only memory ( abbreviated below as rom ) 5 . on the other side , the receiver 11 which is carried in a car body 10 , includes and is composed of an antenna 12 , a receiving circuit 13 , a waveform shaping circuit 14 , a rom 15 , a processing circuit 16 which is realized by a microcomputer or the like , and a level conversion circuit 17 . the same identification data is mutually stored in rom &# 39 ; s 5 and 15 , and this identification data is set individually for each car body 10 . when the push button switch 4 of the transmitter 1 is operated by the operator , the data stored in rom 5 , which includes the identification data , undergoes amplitude modulation and is transmitted from the antenna 2 of the transmitter 1 . in the receiving standby mode for times such as when the automobile is stopped , the data signal from transmitter 1 is received by the antenna 12 , goes through the receiving circuit 13 , is shaped into a data pulse in the waveform shaping circuit 14 , and is input to the processing circuit 16 . in the processing circuit 16 , when the identification data of the inputted data pulse matches the identification data stored in the rom 15 , the operation mode , of an electromagnetic solenoid 21 as locking / unlocking means for the doors and trunk or the like of the car body 10 , is switched . namely , when the doors and trunk or the like are in an unlocked condition , they will be put into a locked condition by the operation of the push button switch 4 . also at this time , the change to the locked condition is reported to the operator by performing the response operations of sounding a horn 22 one time , together with the lighting of a stop indicator lamp 23 one time . as opposed to this , when they are in a locked condition , they will be put into an unlocked condition by the operation of the push button switch 4 . also , the change to the unlocked condition is reported to the operator by performing the response operations of sounding the horn 22 two times , together with the lighting of the stop indicator lamp 23 two times . the so called keyless entry is realized in this way . moreover , auto theft sensors , such as a hood switch 24 that turns on when a hood is opened , and a courtesy switch 25 that turns on when the door is opened , are connected to the processing circuit 16 . when a setting status of a security switch 26 is turned on , and then the hood switch 24 or courtesy switch 25 or the like are turned on , the processing circuit 16 activates a theft alarm sounding the horn 22 . further , the output from all of the switches 24 through 26 is read into the processing circuit 16 , after being converted by a level conversion circuit 17 to correspond to the input level of the processing circuit 16 . the data d of the data signal transmitted from the transmitter 1 to the receiver 11 , as shown for example in fig2 is composed of a bit synchronization data d1 , a frame synchronization data d2 , and an identification data d3 . when all of the data match , the door locking / unlocking operations are carried out . further , when the data receiving state as described above continues and lasts for longer than the preset time period w , then in response to the operation in the transmitter 1 , it is determined that the car body 10 is being exposed to theft and the security operation is performed . in other words with this operation , when the car is about to be stolen , or when a rider is about to get into the car and is assaulted by a thug , the person carrying the transmitter 1 activates the security operation and frightens the thug by operating the push button switch 4 for longer than the time period w . the security operation is , for example , the sounding of the horn 22 and the flashing of the stop indicator lamp 23 during a preset time period wa . fig3 is a flow chart that explains the data receiving operation of the receiver 11 , which is one example of the invention . at step s1 , it is determined whether or not the data d has been received , and when data d has been received flow moves to step s2 . it is determined that data d has been received when the bit synchronization data d1 and the frame synchronization data d2 are correct . at step s2 , it is determined whether or not the identification data d3 is in agreement with data in the receiver . when it is not in agreement flow returns to the step s1 , and when the data is in agreement flow moves to step s3 . at step s3 , setting or resetting of the security operation is performed . that is to say , if the present status is the &# 34 ; set &# 34 ; status , then resetting will be performed upon operation , and if it is the &# 34 ; reset &# 34 ; status , then setting will be performed upon operation . next at step s4 , the door locking / unlocking operation is performed . that is to say , if the present condition is the locked condition , then it will be unlocked upon operation , and if it is the unlocked condition , then it will be locked upon operation . further , when setting is performed at step s3 the door will be locked at step s4 , and when resetting is performed at step s3 the door will be unlocked at step s4 . also at this step s4 , the response operation is performed which indicates that the operation in question has been performed . at step s5 , from the point at which in this way the receiving of data d begins , the timer in the processing circuit 16 begins a counting operation . at step s6 , in the same way as step s1 , it is determined whether or not the receiving of the data d is being continued ; when it is not , this step s6 is repeated , and when the receiving of the data d is being continued , flow moves to step s7 . at step s7 , collation of the identification data d3 is performed again ; when there is agreement flow moves to step s8 , and when there is not agreement flow returns to step s1 . at step s8 , it is determined whether or not a timer &# 39 ; s counting time w1 is more than the preset time w , for example , about 2 seconds ; when flow is not , it returns to the step s6 , and when the time w has elapsed , flow moves to step s9 . at step s9 , flow returns to the step s1 after the security operation is performed . in this way with steps s6 through s9 , the security operation is realized by means of operation in the transmitter 1 . when data d is not received at the step s1 , flow moves to step s10a where it is determined whether or not security is set , and if set , it is then determined whether or not theft is occurring at step s10b . if theft is occurring flow then moves to the step s9 and the security operation is performed . in this way with steps s10a , s10b , and s9 , the security operation is realized by means of the car &# 39 ; s theft sensors . further , when security is not set at step s10a , and when it is determined at step s10b that theft is not occurring , flow returns to step s1 , and when in this way data d is not received and theft is not detected , these steps s1 , s10a , and s10b are repeated . fig4 is a flow chart that explains the security operation . at step s41 , the timer &# 39 ; s counting operation is started . at step s42 the horn 22 is blown , and at step s43 flashing of the stop indicator lamp 23 is performed . at step s44 , it is determined whether or not the timer &# 39 ; s counting time w1a has elapsed only as far as the preset time wa , for example about 60 seconds ; when flow has not , it returns to the step s42 continuing the security operation , and when it has , the operation is finished . in this way with the receiver 11 which conforms to the invention , simplification of construction together with a marked improvement in functionality are made possible , because two operations , the door locking / unlocking operation and the security operation , have been realized in accordance with the operational state of the push button switch 4 , without using a special construction such as a squelch circuit , as in the prior art . fig5 is a flow chart that explains the data receiving operation of another example of the invention , and as this example is similar to the previously discussed example , the same reference numbers will be given for the corresponding parts . in this example , when the data d is in agreement at step s7 , flow moves to step s8 after performing the counting operation for the count value n1 of the counter in the processing circuit 16 at step s1 . further , when the receiving of data d is not detected at step s6 , and when the data d is not in agreement at step s7 , flow moves directly to step s8 . at step s8 , when the timer &# 39 ; s counting time w1 passes the preset time w , flow moves to step s12 where it is determined whether or not the count value n1 is greater than the preset value n ; when it is greater , flow moves to the step s9 and the security operation is performed , and when it is not greater , the counter &# 39 ; s count value is reset at step s13 and flow then returns to the step s1 . further , for example , data d is transmitted from the transmitter 1 about 20 times during the time period w of 2 seconds , and for this reason the value of n is set to about 16 . therefore , even in cases where some receiving errors are generated due to noise or other factors , it is possible to determine the continuous receiving condition and to realize a greater degree of accuracy in the security operation . fig6 is a flow chart that explains the data receiving operation of yet another example of the invention , and as this example is similar to the previously discussed example , the same reference numbers will be given for the corresponding parts . in this example , at step s19 , it is determined that the continuous receiving is taking place if the bit synchronization data d1 is in agreement , and at that time it is determined at steps s20 and s21 respectively , up to what point the data contained in the data d has been received error free , and based upon the results of that determination , the counting operation is performed at steps 22 through 24 respectively . in other words , when all of the data d up to the identification data d3 is received error free , flow moves from step s20 to step s22 , and all of the count values , the count value na of the bit synchronization data d1 , the count value nb of the frame synchronization data d2 , and the count value nc of the identification data d3 , are added together . further , when the reception up to the frame synchronization data d2 is error free , flow moves from step s21 to step s23 , and the count value na of the bit synchronization data d1 and the count value nb of the frame synchronization data d2 are added together . still further , when only the bit synchronization data d1 is received , flow moves from step s21 to step s24 , and the count value na of the bit synchronization data d1 is added . from the steps s22 through s24 flow moves to step s25 , and after the count value w11 , which indicates the fact that data d has not been received , has been reset , flow moves to the step s8 . further , when continuous receiving of data d is not detected at the step s19 , and after adding the count value w11 at step s26 , flow moves to step s27 . at step s27 , it is determined whether or not the count value w11 is greater than the preset value w10 , and when it is , that is to say when the nonreceiving condition continues , for example , for longer than the count value w10 of about 0 . 4 seconds , all of the count values are reset at step s28 and flow returns to the step s1 . moreover , when the count value w11 at step s27 is less than the value w10 , flow moves to step s8 . at step s8 , it is determined whether or not the timer &# 39 ; s counting time w1 has become greater than the preset time w , and when it has not , flow returns to the step s19 , and when it has , flow moves to step s31 . at steps s31 through s33 , conditions are determined as to whether or not all of the count values n1a , n1b , and n1c are respectively greater than the preset values na , nb , and nc , and only when all of those conditions are satisfied , flow moves to the step s9 and the security operation is performed ; when any one of those conditions is not satisfied , flow returns to step s1 after all of the count values are reset at the step s28 . further , for example , the value na is set to 16 , the value nb is set to 10 , and the value nc is set to 6 . according to this example , with the continuation of a favorable receiving state , all of the conditions indicated in the steps s31 through s33 are satisfied , and moreover , since the security operation is performed only when the count value w11 of the nonreceiving condition at step s27 is less than the preset value w10 , it is possible to improve accuracy still further based upon this . fig7 is a block diagram that shows the electrical construction of the communication apparatus 30 , in which another example of the invention , the receiver 31 , is used , and as this example is similar to the previously discussed example , the same reference numbers will be given for the corresponding parts . in this example , when the push button switch 4 is operated , a transmission circuit 33 of a transmitter 32 performs fsk ( frequency shift keying ) modulation on , for instance , a 30 mhz carrier wave and then transmits it from the antenna 2 in accordance with the data stored in rom 5 , which includes the identification data . the receiver 31 which is carried in a car body 40 receives the data from the transmitter 32 with the antenna 12 , and reads the data into the processing circuit 36 after it is demodulated in a receiving circuit 34 and formed into a data pulse in a waveform shaping circuit 35 . when the identification data of the read in data matches the identification data stored in an eeprom ( electrically erasable programmable rom ) 37 , a processing circuit 36 changes the operating state of the electromagnetic solenoid 21 , in response to the output from a switch group 38 which will be discussed later . switch group 38 is a group of switches for establishing which door &# 39 ; s locking / unlocking is to be controlled , and for example , is composed of switches such as a door switch 38a for setting the door control , a hood switch 38b for setting the engine hood control , and a trunk switch 38c for setting the trunk control . the output of this switch group 38 is read into the processing circuit 36 after being converted to correspond with the input level of the processing circuit 36 , in a level conversion circuit 39 . further , a status setting switch 41 is provided in conjunction with the processing circuit 36 . when this status setting switch 41 is turned on , the eeprom 37 is set to a writable status , and it is possible to register the identification data d3 of the received data d , which is input by way of the receiving circuit 34 from the antenna 12 . as opposed to this , when the status setting switch 41 is turned off , the eeprom 37 is set to a readable status , and each time a data signal is received from the transmitter 32 , the identification data is read out from the eeprom 37 and compared with the identification data d3 from the transmitter 32 . as a result of the comparison , in the case where the two sets of identification data are the same , the regular keyless entry control is performed , which controls the locking / unlocking of the doors . moreover , switches 24 through 26 for the security may also be connected to the processing circuit 36 . further , a reporting means 42 is connected to the processing circuit 36 . means such as a led ( light emitting diode ) 43 and a horn 44 are given as examples of the reporting means 42 . further for this horn 44 , the horn 22 which generates the alarm sound may be used in common , or a buzzer or the like may be used . the reporting means 42 , reports on such conditions as whether or not the eeprom 37 is in a writable status , and further , whether or not the writing of the identification data has been completed . for example , the led 43 may light up or flash while set to the writable status , and the horn 44 may blow when the writing of the identification data into the eeprom 37 is completed . fig8 is a flow chart that explains the operation of receiver 31 . at step l1 , it is determined whether or not the status setting switch 41 is turned on . in other words , it is determined whether or not the eeprom 37 is set to the status in which the identification data can be written , and when it is not , flow proceeds to step l6 and performs regular keyless entry control is performed . that is to say , the identification data d3 which is transmitted from the transmitter 32 is compared with the identification data stored in the eeprom 37 , and as a result , if the door is in a locked condition , the unlocking control is performed , and if the door is in an unlocked condition , the locking control is performed . in this way the door &# 39 ; s locking / unlocking control is performed in response to the data signal from the transmitter 32 . when the status setting switch 41 is turned on at the step l1 , the led 43 of the reporting means 42 lights up at step l2 . at step l3 , it is determined whether or not the identification data d3 which is to be registered has been received by the receiving circuit 34 , and when it has not been received , flow proceeds to step l4 and it is determined whether or not the status setting switch 41 has been turned off , or in other words , whether or not the writable status of the eeprom 37 has been released . in the case that the status setting switch 41 has not been turned off , the processing returns to step l3 and the determination is repeated . in this way , when the status setting switch 41 is turned off , flow proceeds from step l4 to step l5 , and with the release of the writable status the led 43 turns off , and the regular keyless entry control is returned to . on the other hand , while the eeprom 37 is set to the writable status , when the identification data d3 which is to be registered is received at the step l3 , flow proceeds to step l7 , the processing circuit 36 is set to the write mode , the identification data d3 is written into the eeprom 37 at step l8 , after the writing is completed the horn 44 of the reporting means 42 is blown one time , and then after determining the conclusion of the writable status at step l4 , the regular keyless entry control is returned to . therefore , according to the example described above , the writable status of the eeprom 37 , which is connected to the processing circuit 36 , is set by changing the status setting switch 41 , and when in the writable status , reading and registering can be easily accomplished by receiving the identification data d3 which is to be registered from the transmitter 32 . consequently , for example , even when the transmitter 32 is lost and it is necessary to register the identification data for a new transmitter 32 , registering into the eeprom 37 of the receiver 31 can be accomplished easily . in other words , there is no need for troublesome operations such as the replacement of memory parts in order to register new identification data , as has been the case up until now , and it is possible to hold down the cost of maintenance part management . still further , because the reporting means 42 is provided , it is possible for the operator to easily confirm factors such as the writable status and the completion of writing , which makes for excellent operability . further , since the status setting switch 41 is constructed with two stable positions , the operator can operate it while fully confirming the status , and malfunction can be prevented . fig9 is a block diagram that shows the electrical construction of the communication apparatus 50 , in which yet another example of the invention , the receiver 51 , is used , and the same reference numbers are used for parts which correspond to the previous example . in this receiver 51 , timer 53 is provided in a processing circuit 52 which controls the locking / unlocking of the doors , and further , a status setting switch 54 is composed of two switches 54a and 54b . the status setting switch 54 does not have two stable positions like the previously mentioned status setting switch 41 , but is constructed so that , as with a so called push switch , a single pressing operation outputs a one pulse signal . in this example , once switch 54a is operated , the eeprom 37 is set to the writable status and the timer 53 begins to count , from that point of operation . when the count value t of the timer 53 reaches the preset value t , for example 5 seconds , the writable status of the eeprom 37 is automatically released . further , the processing circuit 52 has a function for clearing the stored contents within the eeprom 37 . in other words , it is constructed so as to clear the stored contents of the eeprom 37 after the switch 54a is operated , and when the switch 54b is operated before the count value t of timer 24 passes the preset value t . the time for determining that the switch 54b has been operated is selected , for example , to be about 2 seconds . fig1 is a flow chart that explains the operation of receiver 51 . at step m1 , it is determined whether or not the operation of switch 54a , for the registering of the identification data , has been performed , and when it has not , flow proceeds to step m7 and the kind of regular keyless entry control previously mentioned is performed . further , when switch 54a has been operated at step m1 , flow proceeds to step m2 , sets the eeprom 37 is set to the writable status , and together with the lighting or flashing of led 43 , counting with the timer 53 begins . after that , it is determined at step m3 whether or not switch 54b has been operated . in case the determination is negative , the identification data d3 which is to be registered at step m4 is transmitted from the transmitter 32 , and it is determined in the receiving circuit 51 whether or not the data has been received . in case the determination at the step m4 is negative , the processing proceeds to step m5 and it is determined whether or not the count value t of the timer 53 has exceeded the preset value t . in case the determination at the step m5 is negative , the processing returns again to step m3 , and the processing of the above mentioned steps m3 through m5 is repeated . when the count value t exceeds the preset value t , the processing proceeds to step m6 , it is determined that the write registration of new identification data was not performed within the preset time period , the writable status of the eeprom 37 is released , together with the turning off the led 43 , the count value t of timer 53 is cleared , and at step m7 regular keyless entry control is performed similar to that mentioned above . on the other hand , when it is determined that the switch 54b has been operated before the count value t of the timer 53 has reached the preset value t at the step m3 , the eeprom 37 is set to the clear mode at step m8 , all of the stored contents are cleared at step m9 , the horn 44 is blown once at step m10 , and the processing proceeds to the above mentioned step m6 . further , when the identification data d3 which is to be registered at the step m4 is received before the count value t of the timer 53 reaches the preset value t , the processing moves to step m11 , the eeprom 37 is set to the write mode , the received identification data d3 is written at step m12 , the horn 44 is blown twice at step m13 , and the processing proceeds to the above mentioned step m6 . the reason that the horn 44 is blown a different number of times at the steps m10 and m13 is that the respective objectives of blowing the horn 44 are , to clearly report to the operator the difference between the clearing of the eeprom 37 , and the completion of writing to the eeprom 37 . therefore the number of times the horn 44 is blown , is not limited in this example . in this way based upon the above example , it is possible to easily register the identification data d3 of the transmitter 32 into the receiver 51 , with a simple operation similar to the examples shown in fig7 and 8 above . further , forgetting to change the switch , such as when the operator leaves the eeprom 37 set to the writable status through carelessness or the like , can be prevented , because when the identification data d3 to be registered is not received within the time period clocked in advance using the clocking means , timer 53 , the writable status of the eeprom 37 is released automatically . moreover , the selection of the write mode and clear mode for the eeprom 37 can be implemented with a simple operation of the status setting switch 54 , making for very high operability . furthermore , because a clear mode is provided for the eeprom 37 , when for example , the operator leaves the automobile for a long period of time , by clearing the stored contents of the eeprom 37 it becomes impossible to release the door locks with a transmitter having any kind of identification data , and security is improved greatly . fig1 is a block diagram that shows the electrical construction of a communication apparatus 60 , in which another example of the invention , the receiver 61 , is used , and the same reference numbers are used for parts which correspond to the previous example . in this receiver 61 , a status setting switch 63 , which is connected to a processing circuit 62 that controls the locking / unlocking of the doors , is composed of one push switch . in other words , the example shown in fig9 above is constructed so that the switch 54a is operated when the eeprom 37 is set to the writable status , and furthermore the switch 54b is operated when the eeprom 37 is set to the clear mode during the preset period t , however , one common status setting switch 63 can be used for these switches 54a and 54b . that is to say , it should be constructed so that when the eeprom 37 is set to the writable status , and once the status setting switch 63 is operated , at that time the counting of timer 53 is started , and by a second operation of the status setting switch 63 during the preset period t , the eeprom is set to the clear mode . further , it is constructed so that in case the second operation of the status setting switch 63 is not performed by the time the count value t of timer 53 exceeds the preset value t , the writable status of the eeprom 37 is released automatically . fig1 is a flow chart that explains the operation of receiver 61 , and the same reference numbers are used for parts that correspond to the previous fig1 . since as before , the two switches 54a and 54b are replaced with a single status setting switch 63 , step m1 which is indicated in fig1 is replaced with step m1a of fig1 , and becomes the determination of whether or not the status setting switch 63 has been operated once . further , the determination of the operation for switch 54b at step m3 of the fig1 , is replaced with the determination of whether or not the second operation of the status setting switch 63 has been performed at step m3a in fig1 . the other processing operations are the same as the processing shown in fig1 , and are omitted here . based on the above receiver 61 , since the two operation switches 54a and 54b used in receiver 51 are combined in the common status setting switch 63 , the space occupied by the status setting switch 63 in the apparatus is reduced together with a curtailment of the number of parts . further , for all of the switches 54a , 54b , and 63 , momentary switches may be used . fig1 is a block diagram that shows the construction of a receiver apparatus 70 , which is yet another example of the invention , and the same reference numbers are used for parts which correspond to the previous example . in this example , a number of transmitters ( indicated as &# 34 ; n &# 34 ; in the example ) are provided , and it is supposed in this case that mutually different identification data r1 through rn ( indicated by the reference number &# 34 ; r &# 34 ; when generalized below ) are stored in the rom &# 39 ; s m1 through mn of the receivers u1 through un ( indicated by the reference number &# 34 ; u &# 34 ; when generalized below ). in a case such as this where a number of transmitters u is provided , it is necessary for all of the identification data r1 through rn , which are assigned to the transmitters u , to be registered in an eeprom 72 of a receiver 71 , so that any of the transmitters u can perform the keyless entry control . the interior of the eeprom 72 is divided into a number of storage areas . in this example , as one illustration it is supposed that the eeprom has been divided into &# 34 ; k &# 34 ; areas , and it is possible to write and register &# 34 ; k &# 34 ; sets of identification data r . in this example the registration order is established so that in the case of registering identification data r which exceeds the number of areas k , priority is given to the most recently registered identification data . fig1 is a drawing that explains the storing status of the eeprom 72 . there are k storage areas for which the reference numbers m1 through mk are given . fig1 a shows the condition of the first identification data r1 registered in the storage area m1 . continuing , when the status setting switch 63 etc . is operated so that the identification data r2 will be registered , as is shown in fig1 b , the identification data r1 which was registered in the storage area m1 is shifted to the adjacent storage area m2 , and then the new identification data r2 which is to be registered , is written and registered into the storage area m1 that has been cleared . thereafter in the same way , with each new registration , the previously registered identification data r is shifted consecutively to the adjacent storage area . in this way , when k sets of identification data are registered , as is shown in fig1 c , identification data r is registered respectively in all of the k number of storage areas m1 through mk . furthermore , in the case when new identification data r ( k + 1 ) is registered , the identification data r1 , which was registered the earliest , is cleared from the last storage area mk , as is shown in fig1 d . after that , the data are shifted in sequence as stated above , and the newest identification data r ( k + 1 ) is written and registered into the storage area m1 . in this way , the eeprom is constructed so that identification data can be registered into eeprom 72 while giving priority to the newest data . fig1 is a flow chart that explains the replacement operation for registered contents as mentioned above . when the replacement processing begins , the stored contents in the last storage area mk are cleared at step a1 . that is to say , the identification data which was entered the earliest and which has been shifted to the last storage area mk , is cleared . at step a2 , the stored contents of the storage area m ( k - 1 ) is shifted to the adjacent storage area mk which has been cleared , and thereafter the shifting process is sequentially repeated . after that at step ak , the stored contents of the first storage area m1 is shifted , and in this way the identification data to be newly registered secures the storage area m1 in which it should be registered , and the replacement processing of the stored contents is completed . fig1 is a flow chart that explains the operation of receiver 71 . at step b1 , it is determined whether or not the operation of the status setting switch 63 has been performed for the first time , and when it has not been operated , processing proceeds to step b17 , the above mentioned regular keyless entry control is performed , and step b1 is executed again . on the other hand , if the determination is affirmative , the processing proceeds to step b2 , the eeprom 72 is set to the writable status , and together with the lighting or flashing of the led 43 , the counting of timer 53 starts , and at step b3 it is determined whether or not the count value t has exceeded the preset value t . in case the determination is negative , processing proceeds to step b4 and it is determined whether or not the second operation of the status setting switch 63 has been performed . in case the determination at the step b4 is negative , the processing proceeds further to step b5 and it is determined whether or not the identification data r to be registered has been received . in case the determination is negative , the processing returns again to step b3 where the determination of the count value t and the preset value t is performed , and the processing of steps b3 through b5 is repeated . when the identification data r to be registered is received at the step b5 , it is preset into the processing circuit 62 at step b6 , + 1 is added to replace &# 34 ; 0 &# 34 ; as the count value c of a receiving counter , and at step b7 it is determined whether or not the count value c is &# 34 ; 1 &# 34 ;. in case the count value c is &# 34 ; 1 &# 34 ;, processing proceeds to step b8 where the processing circuit 62 is set to the write mode , the received identification data r is written to the eeprom 72 at step b9 , and the processing returns again to step b3 . in general , the identification data r which is sent from a transmitter u is sent a number of times at the same level , and the construction is such that at the receiver 71 , the identification data r can be evaluated and registered with certainty . therefore , in case the count value c is not &# 34 ; 1 &# 34 ; at the step b7 while the processing of the steps b3 through b7 is being repeated , the processing proceeds to step b10 . at step b10 , it is determined whether or not the identification data r received at a current time is the same as the identification data r received the previous time , and when it is , the count value c at step b11 is newly set to &# 34 ; 1 &# 34 ;, the processing returns to step b3 , and the processing of the above steps b3 through b7 , b10 and b11 is repeated . when it is determined at the step b10 , that the identification data r received at a current time is different than the identification data r registered in the eeprom 72 the previous time , processing proceeds to step b12 where the replacement processing shown in the above mentioned fig1 is performed , and secures the first storage area m1 in a writable status . at step b13 , the eeprom 72 is set to the write mode , and the new identification code data r is written to the storage area m1 at step b14 . after that , the horn 44 is blown once at step b15 , and at step b16 the writable status of the eeprom 72 is released , and together with the turning off of the led 43 , the count value t of timer 53 is cleared . as a result , the processing circuit 62 performs regular keyless entry control at step b17 , and the processing returns again to step b1 . on the other hand , when at the step b3 , the count value t of timer 53 , from the point of the first operation of the status setting switch 63 , exceeds the preset value t , the processing proceeds to step b16 and the writable status of the eeprom 72 is automatically released . furthermore , at the step b4 , when the second operation of the status setting switch 63 is performed before the count value t of the timer 53 reaches the value t , processing moves to step b18 where the processing circuit 62 is set to the clear mode , all of the stored contents of the eeprom 72 are cleared at step b19 , reporting is performed by blowing the horn 44 twice at step b20 , and then processing proceeds to step b16 . therefore according to the above example , operability is markedly improved , because the apparatus is constructed so that in registering to the eeprom 72 , greater priority is given to the most recently registered identification data , than to the earliest registered identification data , which can be considered to be less in demand . therefore based upon the above example , it is possible to greatly simplify the control and registering of the identification data r from the transmitters u to the receiver 71 at the manufacturing stage . also for example , even in the case where a transmitter is lost and a transmitter with new identification data is procured , maintenance is simple because write registration of the new identification data to the receiver can be carried out easily . 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 .