| 摘要 |
PURPOSE:To omit the rewriting of a register that indicates the address of an externally extended memory by providing plural address pointers to designate the addresses of the extended memory and attaining the independent replacement of addresses of each address pointer. CONSTITUTION:The 1st and 2nd address pointers 12 and 13 transfer data with an internal data bus 1 and also serve as registers to designate the address of an external RAM 19. An input register 14 stores temporarily the data supplied through a data input/output terminal 18. While an output register 15 stores data temporarily when data are sent to outside via the terminal 18. A selector 16 selects the outputs of the 1st and 2nd address pointers 12 and 13. An address output terminal 17 delivers an address to the RAm 19 and the terminal 18 performs input and output of data with the RAM 19 respectively.
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