| 摘要 |
PURPOSE:To attain the application of a general-purpose microcomputer with no addition of an external circuit by providing a programmable logic array PLA to an I/O port. CONSTITUTION:The data are transferred among a CPU 1, a RAM 2 and a ROM 3 via a bus line 4. The I/O signals sent from I/O ports 11-14 are applied to a programmable PLA 10. An interruption processing circuit 40 is controlled by the output of the PLA 10. Therefore the input terminals Pb0-Pb7, Pc0-Pc7 and Pd0-Pd7, for example, led from the I/O ports 12-14 can be all interrupted. Furthermore it is possible to use two or three of these terminals as the interruption terminals with other terminals used as the ordinary input terminals for I/O ports. |
