System for interface circuit to control multiplexer to transfer data to one of two internal devices and transferring data between internal devices without multiplexer

摘要

Enhanced is a data processing efficiency of a whole semiconductor integrated circuit. A multiplexer is provided on a main parallel data bus for transferring data between an internal device such as a CPU, a DRAM or the like and an external device. When the CPU cannot accept data from the external device, it sends a busy signal to an interface circuit. The interface circuit receives the busy signal and controls the multiplexer in such a manner that the data to be transmitted to the CPU are transferred to the DRAM. Thus, a data transfer rate of the semiconductor integrated circuit is enhanced.