Chapter 6
Programming
©
National Instruments Corporation
6-15
PCI-DIO-96 User Manual
Port C Status-Word Bit Definitions for Output (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
OBFA*
Output Buffer for Port A—A low setting indicates
that the CPU has written data to port A.
6
INTEA
Interrupt Enable Bit for Port A—Setting this bit
enables interrupts from port A of the 82C55A.
Control this bit by setting/resetting PC6.
5–4
I/O
Input/Output—These bits can be used for
general-purpose I/O when port A is in mode 1
output. If these bits are configured for output, you
must use the port C bit set/reset function to
manipulate them.
3
INTRA
Interrupt Request Status for Port A—When INTEA
and OBFA* 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
OBFB*
Output Buffer for Port B—A low setting indicates
that the CPU has written data to port B.
0
INTRB
Interrupt Request Status for Port B—When INTEB
and OBFB* are high, this bit is high, indicating that
an interrupt request is pending for port B.
7
6
5
4
3
2
1
0
OBFA*
INTEA
I/O
I/O
INTRA
INTEB
OBFB*
INTRB