| 摘要 |
<p>PURPOSE:To quickly access a window by providing window area start and end address holding means, counters, comparing means, etc., to reduce the burden on software. CONSTITUTION:The start address is set to a register 4 and a counter of the window area start address holding means, and the end address is set to registers 6 and 7. The increment address from a counter 8 and the address from the counter 5 are processed in comparators 12a and 12b through a selector 9: and when the increment address coincides with contents of the register 6, contents of the register 4 are set to the counter 8 again through a controller 13 and contents of the counter 5 are incremented by +1. A CPU 1 repeats the same operation to access a window area of a RAM 10 with only setting of start and end addresses. Meanwhile, addresses other than the address of the window area from the CPU 1 and an I/O 13 are inhibited by comparators 11a, 11b, 12a, and 12b, and the burden on software is reduced in any case to quickly access the window.</p> |
