Chapter 6
Programming
PCI-DIO-96 User Manual
6-12
©
National Instruments Corporation
Port C Status-Word Bit Definitions for Input
(Ports A and B)
Address:
Base a 03 (hex) for PPI A
Base a 07 (hex) for PPI B
Base a 0B (hex) for PPI C
Base a 0F (hex) for PPI D
Type:
Read and write
Word Size:
8-bit
Bit Map:
Bit
Name
Description
7–6
I/O
Input/Output—These bits can be used for
general-purpose I/O when port A is in mode 1 input.
If these bits are configured for output, the port C bit
set/reset function must be used to manipulate them.
5
IBFA
Input Buffer Acknowledgment for Port A—A high
setting indicates that data has been loaded into the
input latch for port A.
4
INTEA
Interrupt Enable Bit for Port A—Setting this bit
enables interrupts from port A of the 82C55A.
Control this bit by setting/resetting PC4.
3
INTRA
Interrupt Request Status for Port A—When INTEA
and IBFA are high, this bit is high, indicating that an
interrupt request is pending for port A.
2
INTEB
Interrupt Enable Bit for Port B—Setting this bit
enables interrupts from port B of the 82C55A.
Control this bit by setting/resetting PC2.
1
IBFB
Input Buffer Acknowledgment for Port B—A high
setting indicates that data has been loaded into the
input latch for port B.
0
INTRB
Interrupt Request Status for Port B—When INTEB
and IBFB are high, this bit is high, indicating that an
interrupt request is pending for port B.
7
6
5
4
3
2
1
0
I/O
I/O
IBFA
INTEA
INTRA
INTEB
IBFB
INTRB