Electronic processing device for external and internal data using two data processing devices has changeover switch for connecting one device to terminal, and allowing access to reserved buffer region of internal data RAM

摘要

An internal data RAM is provided in at least one of the two data processing devices (2,3), and a circuit is provided for controlling a region of the internal data RAM as a data buffer. A selector switch (4) selectively connects the first or the second data processing device to a terminal, and also connects the connected data processing device to the data buffer. The switch may allow access to the reserved buffer region of respective data processing devices.