| 摘要 |
PURPOSE:To extend both a program address space and a data address space up to their maximum values respectively and at the same time to increase the processing speed with a data access system by duplicating said spaces and switching them by a hardware. CONSTITUTION:For example, an instruction is executed for writing the address data on a DSP 8 forming a microprocessor. In this case, an instruction code is fetched from a program memory 2 in a 1st cycle and decided by an instruction decoder 5. In the case of a write instruction, the output of the decoder 5 is set at a high level. In a 2nd cycle the DS 8 prepares an address and the data to be written. In this case, the output of an FF 61 of an address switch 4 is set at a high level, In a 3rd cycle the DSP 8 writes data into the prepared address and at the same time the output of an FF 62 of the switch 4 is set at a high level. Then the chip of a data memory 3 an be selected and therefore the DSP 8 gives an access to the memory 3. As a result, an address can be extended in a circuit using a DSP.
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