Chapter 3
Signal Connections
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National Instruments Corporation
3-9
PCI-DIO-96 User Manual
INTR
Output
Interrupt Request—This signal becomes high when the
82C55A requests service during a data transfer. The
appropriate interrupt enable bits must be set to generate this
signal.
RD*
Internal
Read—This signal is the read signal generated from the control
lines of the computer I/O expansion bus.
WR*
Internal
Write —This signal is the write signal generated from the
control lines of the computer I/O expansion bus.
DATA
Bidirectional
Data Lines at the Specified Port—This signal indicates the
availability of data on the data lines at a port that is in the output
mode. If the port is in the input mode, this signal indicates when
the data on the data lines should be valid.
Table 3-3. Signal Names Used in Timing Diagrams (Continued)
Name
Type
Description