| 摘要 |
PURPOSE:To improve the processing speed without increasing the load on a CPU in an electronic appliance such as printer by a method wherein the operation of an overlapped writing means is started and performed by an instruction by a CPU while the CPU executes other instructions. CONSTITUTION:A data 101 and address information 109 from a CPU are latched into registers 102 and 110 by a writing pulse 114, a data 121 is outputted from a RAM106 according to information 109 via an adder 111, output 123 via a register 107 and output 116 of a ROM105 are passed through an OR108 to write the data 116 overlapping the data already written into the RAM106. Then, after performing a shift processing of the data 117 with a ROM, a main controller 112 writes an exessive portion into the RAM106 by a signal 118 to add 1 to the address with the adder 111. This permits the CPU to execute other instructions aside from the operation of writing into the RAM thereby reducing the load on the CPU.
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