on a piece of paper p paper conveyance is alternately carried out by the paper conveying units 4a and 4b fig1 is a block diagram of an embodiment of a specific cassette selection apparatus in accordance with the present invention an identification unit 60 which identifies the size of paper held in a mounted paper feeding cassette which unit is constituted for example by a magnet and a read switch the relative positions of which are set according to the types of paper feeding cassettes an automatic both side copying mode selection key 61 a print key 62 and a cassette selection key 63 are connected to a microcomputer 65 through an input port 64 a control signal from the microcomputer 65 is supplied through an output port 66 to clutch drive units 67 for controlling the drive of the respective paper feeding rollers 41 and display drive units 68 69 70 output signals from the display drive units 68 69 70 are respectively supplied to a paper size display 71 a paper feeding stage display 72 and a copy ready state display 73 fig2 is a flowchart illustrating the operation of the specific cassette selection apparatus at the step 1 it is judged whether or not the automatic two side or both side copying mode has been selected that is whether or not the automatic both side copying mode selection key 61 has been operated when it is judged at the step 1 that the automatic both side copying mode has not been selected the judgment at the step 1 is repeated until it is judged at the step 2 that the print key 62 has been operated when it is judged at the step 2 that the print key 62.