| 摘要 |
PURPOSE:To secure easily the continuance of addresses despite mixture of boards having different memory sizes by using a memory board selector which forms automatically the address space of a memory allocated to a board. CONSTITUTION:For the upper and lower limit values of a board 11, the reference data are obtained as shown in the figures owing to a fact that the memory 11 has a size of 256kB and also serves as the first memory board. The upper limit value of the memory board 11 (the value of a comparator 3) is given to the input (i) of a comparator 14 of a board selector 16 and serves as the lower limit value of a memory board 12. Then the upper limit value of the board 12 is equal to the value obtained by adding its lower limit value to a memory size 512kB of its own. This upper limit value is delivered as the lower limit value of a memory board 13. In such a way, both upper and lower limit values are decided up to a memory board 14.
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