| 摘要 |
PURPOSE:To shorten considerably a time needed for partial rewriting of data by executing simultaneously the reading of old data by shift action, the partial change of the old data and the writing of new data by the shift action, respectively. CONSTITUTION:A controller 2 of a diagnosing device 20 holds only the part to be changed out of the contents of a shift register 11-1 at the corresponding bit position in a data register 21 and sets '1' at the bit position in a mask register 22 corresponding to data and '0' at another bit position. Then the contents of registers 11-1, 21 and 22 are shifted simultaneously and delivered to serial transfer paths SP1, SP3 and SP4 respectively. Here a selector 23 selects the SP3 and SP1 when the value of the SP4 is equal to '1' and '0' respectively. Then data are transferred to the register 11-1 via a serial transfer path SP2. Thus the contents of the register 11-1 are rewritten. |
