| 摘要 |
PURPOSE:To reduce load to a CPU by allowing the I/O device which requests data transfer to perform setup operation to a register group in a data transfer controller. CONSTITUTION:When the I/O device 80-1 is allowed to use an external bus 20, it outputs an address, data, and write signal to an address bus 23, data bus 32, and read/write line 21 respectively. It specifies a derised register in the register group 52 of the data transfer controller 33 of the CPU 60, and completes the setup of the register group 52 separately from a processor 31. The data controller 33 makes the I/O equipment 80-1 and MM12 write status and read status respectively, and performs data transfer regardless of the CPU. |
