| 摘要 |
<p>PURPOSE:To arbitrarily switch the arrangement of address space in the case of peforming operations as a microcomputer and in the case of performing the operations as a system connected with an external memory and to optimally arrange an internal ROM area in the address space. CONSTITUTION:By the operation of an address space switching circuit 8, when the address signals of the range of addresses from '000087H' to '00DFFFH' are outputted from a CPU 21 for instance, an OR gate 7a selects the area inside a bank 0 of the addresses from '000037H' to '00FFFH' as an external extension area. Also, when the address signals of the range of the addresses from '00E000H' to '01DFFFH' are outputted from the CPU 21, the OR gate 7b selects the area inside the banks 0 and 1 of the addresses from '00E000H' to '01DFFFH' as the internal ROM area. Thus, the internal ROM area is optimally arranged in the address space.</p> |
