signals for erasing the contents of the rms 39 s the reading operation is illustrated below in detail with reference to the timing chart of fig1 during a period of horizontal scanning as represented by a signal hsync of fig1 address signals adr are applied to the ram 39 s 211 to 214 and 221 to 224 in the reading mode to simultaneously read the data of the address 0 of ram 39 s the data of ram 39 s 211 to 214 are loaded to the shift register 231 via data bus 32 responsive to load signals ld1 and ld3 and the data of ram 39 s 221 to 224 are loaded to the shift register 241 via data bus 33 as the signals loaded to the shift registers 231 and 241 are successively shifted by shift signals ck1 and ck3 of a period of 50 ns there are obtained the data corresponding to the 0th picture element u2192 second picture element u2192 fourth picture element u2192 sixth picture element on the horizontal scanning line in the form of outputs do1 of the shift register 231 as well as the data corresponding to the first picture element u2192 third picture element u2192 fifth picture element u2192 seventh picture element on.