| 摘要 |
PURPOSE:To transfer the contents of a system ROM to a debugging RAM without passing them through a system RAM by switching the system ROM and the debugging RAM by means of a software. CONSTITUTION:A CPU9 generates a memory switching signal 10 based upon the software to find out OR between an output signal of a memory changeover switch 5 and the memory switching signal 10. An OR gate 11 is connected so as to generate an output to an AND gate 7 and an inverter 6. In case of debugging the contents of the system ROM2, memory switching based upon the software can be made effective by selecting the debugging RAM3 through the switch 5. Consequently, the switch 5 executes memory switching based upon the signal 10 while being kept at a RAM3 selecting state. Thereby, debugging can be executed by means of the same address as that of the ROM2 by executing the debugging in the RAM3 after transferring the contents of the ROM2 to the RAM3 through a register in the CPU9.
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