National Instruments PC-DIO-24/PnP - Manual (Page 34)

Chapter 3 Signal Connections
© National Instruments Corporation 3-11 PC-DIO-24/PnP User Manual
INTR Output 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.
RD* Internal Read Signal—This signal is the read signal
generated from the control lines of the PC.
WR* Internal Write Signal—This signal is the write signal
generated from the control lines of the PC.
DATA Bidirectional 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).
Table 3-3. Timing Signal Descriptions (Continued)
Name
Signal
Direction Description