Abstract

A one-chip control unit for data transmission has a central processing unit for carrying out various processes according to a preliminarily stored program, a memory device for temporarily storing data processed by the central processing unit and data received from an external memory device, an input/output interface for connecting to the external memory device, bus lines connected to these components for transmitting signals therethrough, and a switch circuit for causing signals to pass through the bus lines along different routes, depending on address signals outputted from the central processing unit. The switch circuit may serve to connect the memory device with the input/output interface and to thereby enable signals to be continuously transmitted therebetween directly when the address signal outputted from the central processing unit are specifying an area on the memory device.