| 摘要 |
PURPOSE:To prevent constitution of the titled circuit from going to complication even when the circuit is assembled into an IC internal part by selecting a chip selecting signal with software. CONSTITUTION:Address decoders 18-20 respectively outputs chip selecting signals CS00-CS03, CS10-CS13 and CS20-CS23 by address data from a CPU 11. An I/O port 24 outputs signals bit0 and bit1 for selecting the signal by an I/O output from the CPU 11, respective selectors 21-23 select and process the chip selecting signal inputted from the address decoders 18-20 and supplies it to respective RAM 15-17 as final chip selecting signals CS0-CS2, respectively. The chip selecting signals CS0-CS2 corresponding to the address map of the RAM 15-17 can be determined by the software.
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