PURPOSE: To releive loads on CPUs and I/Os by providing an interbus coupling part, connecting bus loops with the frame constitution of information words transferred via bus loops, with functions required for occupation control.
CONSTITUTION: Through Y bus loops 54W50, an X bus loop 57, and a Z bus loop 58, CPUs 51W53 and I/Os 73W79 are connected and respective bus loops are coupled by interbus coupling parts 59W62. If the CPU 51 sends a start instruction to the I/O 79, the interbus coupling part discriminates the I/O number in a transferred information word, and then sets a bit 1, showing that the I/O79 is occupied by the CPU51, in an occupation controlling table 120. At this time, when the I/O79 is actuated by the CPU52, the table 120 is retrieved and when a 1 is set, a frame showing the occupation is returned to the CPU52. At the same time, a bit 1 showing that the actuation is held temporarily is set in an actuation control table 121. When end interruption is caused by the I/O79, the table 121 is retrieved to inform the CPU52 of the release of the occupation.
NAKANISHI HIROAKI
TAKAMATSU RIYOUICHI
OKADA MASAKAZU
HARA HIDEYUKI
OKA TOSHIHISA
KASANARU HIROKAZU
