| 摘要 |
PURPOSE:To attain a communication even when a trouble is generated in one unit of a system bus by providing a bidirectional buffer connected in parallel to a shared RAM on the way of a system. CONSTITUTION:In an ordinary operation, unit groups connected to the system bus and unit groups connected to the system bus 2 independently and exclusively have the system bus to control. The delivery between the bus 1 and the bus 2 is carried out through the shared RAM3. However, for instance, when the trouble is generated in the CPU21, the contents of a RAM22 cannot be written in the RAM3 by the CPU21. In such a case, the CPU11 validates the bidirectional buffer 4 to make access directly to the RAM22, thereby, the communication can be maintained to the unit except the CPU21. |
