National Instruments PC-DIO-24/PnP User Manual page 34

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Table 3-3. Timing Signal Descriptions (Continued)
Signal
Name Direction
INTR Output
RD* Internal
WR* Internal
DATA Bidirectional
3-11
Chapter 3
Description
Interrupt Request—This signal becomes
high when the 82C55A is requesting service
during a data transfer. The appropriate
interrupt enable bits must be set to generate
this signal.
Read Signal—This signal is the read signal
generated from the control lines of the PC.
Write Signal—This signal is the write signal
generated from the control lines of the PC.
Data Lines at the Selected Port—This signal
indicates when the data on the data lines at a
selected port is available (output) or should
be available (input).
PC-DIO-24/PnP User Manual
Signal Connections