| 摘要 |
PURPOSE:To obtain the bus of respective channels with a simple constitution and equally by assigning plural priorities to respective channels, and requiring the bus by the priority different from the previous obtaining time when the obtaining of the bus is required again in the prescribed time immediately after obtaining the bus. CONSTITUTION:When the channel to need the obtaining of the bus detects that at the time of t1, a selecting signal SEL and a busy signal BUSY are in an inactive condition, a signal line in a data line 1a assigned to a self-channel is raised to a logic 'H' at the time of t2, and at the time of t3, the busy signal BUSY is sent to a busy line 1b. After a channel 2 and the busy signal BUSY, which start the bus obtaining action, are sent, the logical level of signal lines D1-D8 of a data line 1a is investigated and the most priority channel is judged at priority processing circuits 20 and 40 after the prescribed time passes. A channel CH4 judges that a self-channel obtains a bus 1, and sends a selecting signal SEL to a selecting line 1c at the time of t4. |
