DOMINATION PRIORITY CHANGING SYSTEM FOR INPUT AND OUTPUT BUS

摘要

PURPOSE:To give supreme priority to the input and output control device of a low order by causing the priority of the input bus domination of the input and output control device changeable. CONSTITUTION:When a bus domination right requesting signal is outputted from a least significant input and output control device 2-N and a bus domination right change requesting signal is outputted from a bus domination priority change requesting means 25-N of the device 2-N, one of high-order input and output control devices 2-0-2-(N-1), for example, a bus domination priority change receiving means 26-0 of the device 2-0, receives this change requesting signal and devolves the bus domination priority to the device 2-N. Thus, the least significant input and output control device 2-N to be devolved the bus domination priority receives a bus domination allowing signal to execute a by-pass from a channel control device and establishes the bus domination priority with taking priority over the most significant input and output control device 2-0. After that, a data transferring is executed.