| 摘要 |
PURPOSE:To ensure the effective use of a memory and to accelerate the processing speed by allotting previously an all-zero cell to a virtual space where the image data is transferred and then allotting dynamically a real memory when the non-zero data of check unit is transferred. CONSTITUTION:When the image data on a data bus 12 is in an all-zero state, a control circuit 10 cuts the data to a real memory 6. If the data on the bus 12 is in a non-zero state, it is written to the memory 6. In other words, an idle real memory region number is fetched with reference to a cell stack owing to the non-zero data. Then this region number is written to a virtual space memory cell of the corresponding address. An address converting circuit 11 converts the address of an address bus 13 into an address of a memory region of the relevant number. An access is given to the memory 6 with the converted address, and the data on the bus 12 is supplied to the memory 6 via the circuit 10 to be written to the corresponding region. |
