DIO PORT C DATA
BADR3 + 6
PORT C may be configured as an 8-bit port of either input or output, or it may be split into two independent 4-bit ports of
input or output. When split into two 4-bit I/O ports, D[3:0]
make up the lower nibble, D[7:4] comprise the upper nibble. Although it may be split, every
write to Port C is a byte operation. Unwanted information must be ANDed out during reads
and writes must be ORd with current value of the other 4-bit port.
READ/WRITE
D0
D1
D2
D3
D4
D5
D6
D7
0
1
3
2
4
5
6
7
DIO CONTROL REGISTER
BADR3 + 7
The DIO Control register is used configure Ports A,B and C as inputs or outputs. Operation is identical to that of the 8255
in Mode 0.
WRITE
D0
D1
D2
D3
D4
D5
D6
D7
0
1
3
2
4
5
6
7
The following table summarizes the possible I/O Port configurations for the PCI-DAS1000
DIO operatin in MODE 0:
IN
IN
IN
IN
1
1
1
1
OUT
IN
IN
IN
0
1
1
1
IN
OUT
IN
IN
1
0
1
1
OUT
OUT
IN
IN
0
0
1
1
IN
IN
OUT
IN
1
1
0
1
OUT
IN
OUT
IN
0
1
0
1
IN
OUT
OUT
IN
1
0
0
1
OUT
OUT
OUT
IN
0
0
0
1
IN
IN
IN
OUT
1
1
1
0
OUT
IN
IN
OUT
0
1
1
0
IN
OUT
IN
OUT
1
0
1
0
OUT
OUT
IN
OUT
0
0
1
0
IN
IN
OUT
OUT
1
1
0
0
OUT
IN
OUT
OUT
0
1
0
0
IN
OUT
OUT
OUT
1
0
0
0
OUT
OUT
OUT
OUT
0
0
0
0
PORT C
LOWER
PORT B
PORT C
UPPER
PORT A
D0
D1
D3
D4
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