| 摘要 |
PURPOSE:To simplify the software of computer program control by forming a condition preventing the collision of data in a bidirectional bus line and executing data operation under said condition. CONSTITUTION:A bidirectional data bus 3a and a control bus 3b are outputted from a base unit 1 and the data bus 3a is connected to respective state buffers 4a-4e. If it is necessary to read out the contents of the buffers 4d, 4e continuously when data are read in these buffers 4a-4c through the buffer 4c, a control logic 6 turns a control signal for the buffer 4c from L to H at first, and then turns a control signal for the buffer 4d from H to L to switch data reading from the buffer 4c to the buffer 4d. In this case, the base unit 1 outputs a blanking signal BLK, turns the buffers 4d-4e to high impedance and prevents the data from collision, so that the software of computer program control can be simplified. |
