| 摘要 |
PURPOSE:To expands the address space of a central processor and to utilize a bus effectively by providing an address conversion part which converts addresses of part of the address space of the central processor and makes them to correspond to the address space of the central processor. CONSTITUTION:When the central processor 1 accesses some address, a bus selection part 2 selects a system bus 3 or local bus 4. When the local bus 4 is selected, nothing changes as before, but when the system bus 3 is selected, the address conversion part 11 replaces address data that the central processor 1 accesses including the three high-order bits with the contents of the address conversion register 12 of an address conversion part 11 which is written by the central processor 1 previously. Thus, the contents of this register 12 are rewritten to access an optional area obtained by dividing the address space L of the 1st memory by 2<3>. When the unit of access is made minute, the number of the replaced bits is only increased.
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