| 摘要 |
PURPOSE:To obtain a buffer means if data transfer disable state occurs in a front end and to avoid generation of an I/O error by using a data buffer register of front end in common. CONSTITUTION:Front ends FE#a, FE#b are provided respectively between plural input/output devices i/oa and i/ob and a central operation processor CPU for each input/output device so as to transfer data between the CPU and the i/oa, i/ ob. If one of the plural front ends reaches data transfer disable state, a detecting circuit detects the other fron end taking over the data transfer and an output of a data memory of the faulty front end is connected switchingly to a data buffer register of the other normal front end. Thus, the common use of the data buffer register of the front ends is attained. |
