| 摘要 |
PURPOSE:To relieve the load of a transmission control circuit and also to attain ease of troubleshooting of an I/O device by allowing an I/O interface module to exchange data between I/O devices independently of the transmission control. CONSTITUTION:When the I/O interface module 9 starts input/output operation, an ROM address counter 15 is incremented by four by a clock from an input/ output control circuit 13. Then the count value is given to an ROM 14 as an ROM address. The ROM14 outputs an ROM data corresponding to an address given at each time to an internal address bus 20. In a data outputted from the ROM14, a command (CMD) is latched to the input/output control circuit 13, an I/O address (IOAD) is latched to an I/O address register 24 and a memory address (MAD) is latched to a memory address register 23. Then the input/output control circuit 13 performs READ, WRITE, END, and no processing operation according to the read command. |
