PRINTER CONTROL CIRCUIT

摘要

PURPOSE:To prevent a control program from running away and indicate an abnormality when an interterminal faulty connection occurs by introducing for connection two terminals of a connector on a microprocessor which corresponds to the terminal of an IC card arranged in shortcircuit, into the input part of an unmaskable interruption signal circuit. CONSTITUTION:An unmaskable interruption signal circuit of a microprocessor consists of an earth, an earth wire, a terminal 7B, a shortcircuit 3A, a terminal 7A, an unmaskable interruption signal line and a microprocessor arranged in that order. If the unmaskable interruption signal is HIGH, an abnormality processing program stored in ROM is read and an abnormal status is indicated. Subsequently, the level of the unmaskable interruption signal line 5 changes from OV to HIGH and an abnormal status is indicated, if an IC card is imperfectly attached and the terminals 7A, 7B of a connector 7 are disconnected from the terminals 3A, 3B of the IC card even at a single point.