u2266 k i e y i y i u2266 k as mentioned before this signal 34 1 34 is inverted by the nor gate 29 to reset the memory of the shift register 26 accordingly upon termination of the interpolation the selector 30 is switched to select the a input to select and produce the output y sub i of the waveshape memory 10 the output of the selector 30 is supplied to a multiplier 42 and multiplied by an envelope signal provided from an envelope generator 44 through or gate group 43 the envelope generator 44 is controlled by the output of a shift register 45 and enabled while the second waveshape repetitive waveshape is being generated when the start pulse sp is generated the output of an inverter 46 is turned to 34 0 34 so that an and gate 47 which is provided to hold the shift register 45 is disabled and the stored signal in the shift register 45 of the corresponding channel is reset to 34 0 34 in the meantime as mentioned above the waveshape memory 10 starts readout of the first waveshape the waveshape of the rise portion based on the start pulse sp a comparator 48 compares the output of the address counter shift register 17 and the repeat address and when they coincide produces the signal 34 1 34 which is applied to the shift register 45 through an or gate 49 therefore when the first waveshape has been read throughout and the read address becomes the first address of the second waveshape i e the repeat address 34 1 34 is set in the corresponding channel of the shift register 45 and held through the and gate 47 the output of the shift register.