| 摘要 |
PURPOSE:To easily jump to any address by constituting a bank change over circuit of a bank information register circuit, a jump instruction analyzing circuit, an operation code fetch detecting circuit, and a bank designating circuit. CONSTITUTION:A bank information register circuit 1 is assigned to an X address of an I/O address of a CPU. In order to change this content, a bank information is inputted into an accumulator, and Out(X), A is to be performed. The contents of the bank information register circuit 1 are changed over from a bank information indicating a ROM7(1) hitherto to a bank information indicating a ROM7(2), and the bank information is held at an output 8. The CPU performs a next JPAAA. A jump instruction analyzing circuit 2 detects it to output an output signal 9 and holds it. An operating code fetch detecting circuit 3 detects this change point and outputs a signal 10 to a bank designating circuit 4. According to the bank of the ROM7(2), the bank is changed over. The output 9 of the jump instruction analyzing circuit 2 is reset by the output 10 of the operating code fetch detecting circuit 3 at the same time.
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