| 摘要 |
PURPOSE:To operate as a memory having a density converting processing function by an external command by adding a density converting processing circuit to a port memory. CONSTITUTION:An ordinary memory operation is carried out by transmitting an address, data and a read/write signal to a dual port memory controller 4 from the respective ports. When performing the density converting processing, the original dual pot memory functions as a simple input and output device. Accordingly, A CPU of the port A side designates a density converting processing command, a storage leading address to the memory 5 and the number of transfer data are designated. Thereby, in the operation thereafter, a LOW (I/O write) command is successively transmitted. On the density converting processing, the address, the read/write signal and the data are all transmitted from the density converting processing circuit 1 to the dual port memory controller 4.
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