| 摘要 |
<p>PURPOSE:To prevent a collision of a signal in a data bus, etc. by forming a CPU and a memory or an input/output device by a different substrate, providing a bi-directional buffer circuit on a bus line between them, and forming a floating state when a direction of a data is being switched. CONSTITUTION:A CPU1 and a memory 2 are connected by a data bus 3 through bi-directional buffer circuits 4a, 5a and 4b, 5b. A logical circuit 6 inputs and calculates a write control signal WR, a read-out control signal RD, an instruction fetching signal MI which is not shown in the figure, a memory operation control signal MREQ, an input/output circuit operation control signal IORQ, a clock signal, etc. from a CPU1. Also, this circuit outputs a memory write control signal MWT, a memory read-out control signal MRD and other various control signals which are not shown in the figure, controls read-out and write of a data, and forms a floating state when switching the direction of the bi-directional buffer circuits 4a, 5a and 5b, 4b. In this way, a collision of a signal on the data bus 3 can be prevented.</p> |
