| 摘要 |
PURPOSE:To execute addressing of a software-hardware interface with software by providing a selector for switching between a chip selecting output and a data input bus. CONSTITUTION:A chip selecting output 8 is disconnected from a decoder 12 by switching a selector 13 on a program by a CPU port 15. Simultaneously, chip selection is fixed and held by a feedback circuit of a chip selection fixing buffer circuit 14. Software is executed with only internal registers on the program of a ROM3 while selecting the ROM3, where the current executing program is stored, as it is. Next, address allocation of the software-hardware interface is written on the decoder 12 by a data bus 7 switched from the chip selecting output, thereby changing the interface with software.
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