| 摘要 |
<p>PURPOSE:To detect the difference between the packing data put into a program and the card packing state by transmitting a signal onto an individual bus which selects the individual cards to detect the presence or absence of a card packed. CONSTITUTION:The address signal 5 outputted from a CPU to specify a card 1 is decoded by an address decoding circuit 4 to be turned into a card selector signal 6. This signal 6 is sent to the card 1 via an individual bus (b). When the card packing state is detected, a check signal 3 is set at an H level. Thus the signal set on the individual bus changes as follows. That is, the bus (b) is not affected easily by the circuit 4 in a card packing mode. Thus the signal on the bus is sent back to the bus (b) at an L level. In this example, the effect of the signal 3 is also eliminated and therefore the signal on the bus is kept at an H level by a pull-up resistance 8.</p> |
