| 摘要 |
PURPOSE:To locate a memory easily in an address space dynamically, by allocating address areas dynamically in a memory device or releasing the allocation automatically by commands from a CPU. CONSTITUTION:A CPU outputs an address to an address bus AB and turns on a signal S. A controlling circuit 2 turns on a signal REG to a register 3. Then, upper n-number of bits of the bus AB are written in the register 3. When this memory area is accessed, contents of upper n-number of bits of the bus AB are compared with contents of the register 3 in a comparator 4; and if they coincide with each other, a signal C is turned on. When the signal C is turned on, a memory address decoder 5 decodes lower (k-n)-number of bits of the bus AB and outputs the result as a signal SM. Data is written in or is read from the address, which is selected by the signal SM, of a memory cell 6. When the CPU turns on a signal R, a memory device 7 becomes unavailable, and data in this area disappears. |
