an embodiment of a tape recorder of the present invention can accommodate a plurality of cassette tapes coaxially in a pile and drive all or at least one of the cassette tapes simultaneously through one capstan . in the following description of the invention , it is assumed that the tape recorder can accommodate two cassette tapes ( a first and a second cassette tapes ) and that the first cassette tape is equipped for a reproducing function alone while the second cassette tape for recording , reproducing , fast - forwarding and rewinding functions . it is also assumed that a mode selection mechanism is used for selecting the first cassette tape mode , the second cassette tape mode , the dubbing mode in which information reproduced from the first cassette tape is simultaneously recorded in the second cassette tape , or the serial reproduction mode in which reproduction is conducted serially from one after the other cassette tapes . fig3 shows the relationship between the two cassette tapes and the magnetic heads and pinch rollers of the present invention . the first cassette tape 1 and the second cassette tape 2 are vertically and coaxially loaded in a pile . the magnetic heads 3 and 4 and the pinch rollers 5 and 6 are arranged at positions facing the magnetic surfaces of the first and second cassette tapes , respectively . a capstan 7 is mounted adjacent the pinch rollers 5 and 6 . 8 is a sub - chassis , 9 is a main chassis and 10 is a pinch roller shaft . fig4 shows an example of the layout of operation buttons . the operation buttons on the lower row t 1 relate to the first cassette tape 1 and those on the upper low t 2 relate to the second cassette tape 2 . p through p 6 are record , play , fast - forward , rewind , stop / eject and pause buttons , respectively . on the right is a mode selector switch . dubbing , cassette tape 1 , cassette tape 2 or serial reproduction mode is selected by moving the operation knob m of the switch . in this embodiment of the present invention , as understood from the above , the first cassette tape has reproduction and stop / eject functions alone while the second cassette tape has recording , reproducing , fast - forwarding , rewinding , stop / eject and pause functions , namely all the functions which should be provided in a typical tape recorder . the reproduction and stop / eject functions common to both cassette tapes 1 and 2 are effected by operating the common buttons p 2 and p 5 , respectively . the mode selecting operation knob m is set at a desired position for the first cassette tape mode , second cassette tape mode , dubbing mode in which information reproduced from the first cassette tape 1 is recorded in the second cassette tape 2 , or serial reproduction mode in which reproduction from the first cassette tape 1 and the second cassette tape 2 is performed sequentially . fig1 and 2 are plan views showing the essential part of the mode selection mechanism and the recording operation preventive mechanism . a mode selector member 16 comprises a first arm 16a , a second arm 16b , a third arm 16c and a fourth arm 16d , the first arm 16a including pins 16a and 16b to be engaged with a lock release member ( not shown ), the second arm 16b including grooves 16c , 16d , 16e and 16f for defining the mode selector position , the third arm 16c including grooves 16g and 16i and projections 16h and 16j for pinch roller operation , the fourth arm 16d including projections 16k and 16m and grooves 16l and 16n for the blocking member operation . the mode selector member 16 is vertically movable in four steps according to the position of the operation knob m shown in fig4 . 18 is a reproducing operation member and 19 is a recording operation member . the reproducing operation member 18 and the recording operation member 19 move in the upward direction of fig1 and 2 when play button p 2 and rec button p 1 are depressed , respectively . the reproducing operation member 18 is provided with a projection 18a for engagement with the recording operation member 19 , a pin 18b for engagement with a hook 17a of a lock plate 17 , and a pin 18c for pushing the sub - chassis 8 . the recording operation member 19 is provided with a projection 19a for engagement with the projection 18a , a pin 19b for engagement with a hook 17b of the lock plate 17 , an inverted - l - shaped hole 19d with a recording operation preventive step 19c , and a fool - proof groove 19e . the sub - chassis 8 is pulled by a spring 30 in the downward direction of fig1 and 2 . it moves upwardly being pressed by the pin 18c when the reproducing operation member 18 is pushed up . springs 31 and 32 , which are provided between the sub - chassis 8 and levers 5a and 6a of the pinch rollers 5 and 6 , respectively , energize the levers 5a and 6a to rotate clockwise . the levers 5a and 6a rotate around the pinch roller shafts 10 1 and 10 2 as the sub - chassis 8 moves in the upward direction . then the pinch rollers 5 and 6 are pressed against the capstans 7 and 7 2 , respectively . the respective ends 5b and 6b of the levers 5a and 6a extend to the area adjacent the projections and grooves 16g through 16j of the third arm 16c . for simplicity of the drawings , the capstan 7 is indicated by 7 1 and 7 2 and the pinch roller shaft 10 by 10 1 and 10 . sub . 2 as if there were two capstans and two pinch roller shafts . actually , however , there is only one capstan 7 and one pinch roller shaft 10 as shown in fig3 . 25 is a recording operation preventive member which is movable in the lateral directions of fig1 and pulled to the right by a spring 34 . the preventive member 25 includes a pin 25a at a position adjacent the projections and grooves 16k through 16n of the fourth arm 16d of the mode selector member 16 , and a pin 25b located within the hole 19d of the recording operation member 19 . 26 is a fool - proof member which is movable in the lateral directions of fig1 and pulled toward the right by a spring 35 so that the projection 26a of the fool - proof member 26 comes in contact with the erroneous erasion preventive claw , if present , of the second cassette tape 2 and that the end 26b of the fool - proof member 26 is engaged with the groove 19e of the recording operation member 19 as shown by broken line if there is no erroneous erasion preventive claw . 36 is a spring which pulls the lock plate 17 in the rightward direction . operation of the invention is described now with reference to the drawings . fig1 shows the position of each part of the mechanisms when the tape recorder stops its operation in the t 2 mode in which the second cassette tape 2 is selected . in this state , the pin 25a of the preventive member 25 is in contact with the projection 16 m of the mode selector member 16 , so that the preventive member 25 is pushed toward the left . as a result , the pin 25b is located in the left portion of the hole 19d and not engaged with the step 19c of the hole 19d of the recording operation member 19 . when the second cassette tape 2 loaded has an erroneous erasion preventive claw , i . e . is recordable , the fool - proof member 26 is positioned as shown by the solid line with the end 26b not being engaged with the groove 19e . therefore , it is possible to push up the recording operation member 19 . when the recording operation member 19 is pushed up , the reproducing operation member 18 also moves up due to engagement between the projections 18a and 19a . the sub - chassis 8 is then pushed up by the pin 18c , causing the respective levers 5a and 6a of the pinch rollers 5 and 6 to rotate clockwise . however , since the rotation of the lever 5a is restricted by its end 5b being in contact with the projection 16h of the mode selector member 16 , only the lever 6a rotates , pressing the pinch roller 6 alone against the capstan 7 2 ( capstan 7 ). consequently , the second cassette tape 2 alone is driven for recording . at this time , the pins 18b and 19b are engaged with the hooks 17a and 17b , respectively , of the lock plate 17 , so that the recording operation member 18 and the reproducing operation member 19 are locked in the depressed positions . depression of stop / eject button p 5 causes the lock plate 17 to shift leftwardly , whereby the engagement of the pins 18b and 19b with the hooks 17a and 17b is released . the recording operation member 19 and the reproducing operation member 18 then move downwardly , resuming the original state shown in fig1 so that operation of the tape recorder is stopped . a mode detector switch ( not shown ) electrically detects the mode selected by the mode selector member 16 and switches over the control circuit accordingly . fig2 shows the position of each part of the mechanisms when the tape recorder stops its operation in the t 1 mode in which the first cassette tape 1 is selected . in this state , the pin 25a of the preventive member 25 is located in the groove 161 of the mode selector member 16 . therefore , the preventive member 25 is shifted toward the right , causing the pin 25b to be engaged with the step 19c of the hole 19d . as a result , the recording operation member 19 cannot be depressed regardless of whether the second cassette tape 2 is loaded or not and whether the erroneous erasion preventive claw is present or not . in this state , therefore , only the reproducing operation member 18 can be depressed . the end 5b of the pinch roller lever 5a is positioned in the groove 16g of the mode selector member 16 while the end 6b of the lever 6a contacts with the projection 16h . accordingly , when the reproducing operation member 18 is depressed , the lever 5a alone rotates , causing the pinch roller 5 to be pressed against the capstan 7 1 ( the capstan 7 ) so that the first cassette tape 1 is driven . in the serial mode , the pin 25a of the preventive member 25 is positioned in the groove 16n of the mode selector member 16 , so that the preventive member 25 is shifted to the right . consequently , the pin 25b is engaged with the step 19c , hampering the recording operation member 19 from being depressed . in the dubbing mode , as the pin 25a of the preventive member 25 contacts with the projection 16k of the mode selector member 16 , the preventive member 25 is shifted to the left , releasing the engagement between the pin 25b and the step 19c . therefore , it is possible to depress the recording operation member 19 if the second cassette tape 2 loaded is recordable . in the embodiment of the present invention , as described above , the projections and grooves of the mode selector member 16 serve to control the position of the preventive member 25 as well as allow the pinch rollers 5 and 6 to be selectively pressed against the capstan 7 . accordingly , in relation to the function of the foolproof member 26 , recording operation is possible only when the mode with recording function is selected and when the second cassette tape 2 is recordable . thus , according to the present invention , a tape recorder whose operation is natural and therefore with higher value of commodity can be attained by a simple construction . in the above embodiment , the invention is applied to the recording operation preventive mechanism . the invention may be applied to the prevention of other operations such as fast - for - warding and rewinding of cassette tapes when all of the cassette tapes loaded are not equipped for such functions . as obvious from the above , in the tape recorder of the present invention in which at least a first and a second cassette tapes are loadable , the recording operation preventive device releases the recording operation member only when the mode selector member is positioned for the second cassette tape recording mode and when the loaded second cassette tape is recordable . accordingly , the tape recorder of the present invention has no such conventional unnaturalness that recording operation button can be operated when the mode not related to recording function has been selected . operationability and value of commodity of the tape recorder are therefore enhanced . in the above description , the tape recorder can accommodate two cassette tapes . the invention is also applicable to a tape recorder in which three or more cassette tapes can be loaded . while only certain embodiments of the present invention have been described , it will be apparent to those skilled in the art that various changes and modifications may be made therein without departing from the spirit and scope of the present invention as claimed .