| 摘要 |
PURPOSE:To shorten a time necessary for I/O write by executing the operation of 2 bus cycles, which is needed for parameter set to a register, with 1 bus cycle. CONSTITUTION:An index on a data bus 10 is held to one of index registers 1 and supplied to a selector 4. In such a case, when writing to a register 6 is a word write mode, the index on the data bus 10 is selected by the selector 4 and one of the registers 6 is selected according to the said index. Data on the data bus 10 are written to the selected register 6 and the I/O write is finished in one bus cycle. In the case of byte write, the index on the data bus is once held to the register 1 in the first bus cycle and the data are written in the next bus cycle. Then, the I/O write is finished in the 2 bus cycles. |
