| 摘要 |
<p>PURPOSE:To make port extension and RAM extension possible only with a one- chip microcomputer by providing the mode, where the one-chip microcomputer is operated as a port or an RAM, as an operation mode of the one-chip microcomputer. CONSTITUTION:In case of port extension of a one-chip microcomputer 201A, a mode setting circuit 200 is set to the extension mode, and mode setting circuits 200-a and 200-b are set to the port mode. Then, a one-chip microcomputer 201-a is set to the port mode and outputs the port mode to each part of the inside. One of port circuits 208-a is selected through an address decoder and is operated as the port of the circuit 201-A. Circuits 201-a and 201-b can be connected in parallel, and a required number of ports are secured in accordance with a system to be designed, and further, an internal RAM of the circuit 201-a can be used as an extension RAM of the circuit 201A.</p> |
