| 摘要 |
PROBLEM TO BE SOLVED: To always access a mounted memory by continuous addresses regardless of the mounted state of the memory. SOLUTION: When a second standard memory 2 is mounted, a jumper is interposed between jumper terminals 9a and 9b, and the control terminal of a selector 7 is turned into an 'L' level. At this time, the selector 7 respectively applies chip enable CE0-CE4 to a first standard memory 1, a second standard memory 2, and each first - third extended slot 3-5. When the second standard memory 2 is not mounted, any jumper is not interposed between the jumper terminals 9a and 9b, and the control terminal of the selector 7 is turned into an 'H' level by a pull-up resistance 8. At that time, the selector 7 applies 5 chip enable CEO generated by an address decoder 6 to the first standard memory 1, and respectively applies chip enable CE1-CE3 to each first - third extended slot 3-5.
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