| 摘要 |
PURPOSE:To select each request signal by an equal probability, and to execute the selection at a high speed by providing a variable selecting circuit and a priority signal circuit, etc., and re-setting a priority selection order of the next time in accordance with the number of a selected request signal. CONSTITUTION:In an initial state, an encoding circuit 2 monitors a selecting output of a variable selecting circuit 6, detects a selecting output signal continued in excess of a propagation delay time of the circuit 6, and informs its request signal to a request receiving circuit 4, etc. The circuit 4 sends out a request receiving signal 5 to a request generating circuit of its number, etc. in accordance with the received request number, and processing corresponding to the request is executed. In this case, the signal 5 is sent out to a priority signal circuit 7, too, the circuit 7 stores the selecting number in its register 8, and a priority signal is reset and outputted so that its number becomes the lowest order by a decoder 9. Therefore, in case when request generating circuits S0-Sn-1 have sent out at random a request signal, the probability by which a request of each request generating circuit is received by the circuit 4 becomes equal, and the selection is executed at a high speed. |
