| 摘要 |
PURPOSE:To improve noise resistance, by interrupting handshake operation while an NRFD signal is set to a level L. CONSTITUTION:A control system sets signals 58 and 59 on a signal line 54 and an NRFDO signal line 57 to a level H in a stand-by state for reception in command mode. For example, an ATN signal 39 on an ATN signal line 33 drops to the level L in this state to cause transition to the command mode. Simultaneously, an NAND gate 39 is enabled and the signal on the NRFDO line 57 is inverted in logical level and outputted as an NRFD signal 42. Namely, this signal 42 changes to the level L. Consequently, the handshake operation is interrupted. If a noise is generated as a substitute for the ATN signal 30, the NRFD signal 42 returns to the level H immediately. Therefore, malfunction due to the noise is prevented. Thus, the noise resistance is improved. |
