Register Description (For Direct Hardware Control); Figure 9-Register Description - SeaLevel PIO-24.PCI 8008 User Manual

Port C
Port C is written and read to as a single eight bit port, but it has the ability to be configured as
two four bit ports. If both lower and upper nibbles are configure the same then no special
considerations need to be made. But if they are configured differently, one nibble as input, and
one as output then the user will have to keep this in mind. When reading, the input will be
returned on the corresponding upper or lower nibble while the current outputs will be returned on
their corresponding upper or lower nibble. When writing, the corresponding nibble will be
written to the output nibble, while the input nibble will have its output register written to. The
output register can be written to without affecting the inputs.

Register Description (for direct hardware control)

Address Port ID
Port A
Base+0
Port B
Base+1
Port C
Base+2
Base+3 Control Word Port
Int. Config. Port
Base+4
Int. Status Port
Base+5
Sealevel Systems PIO-24.PCI
Mode D7 D6 D5
R/W PAD7 PAD6 PAD5 PAD4 PAD3 PAD2
R/W PBD7 PBD6 PBD5 PBD4 PBD3 PBD2
R/W PCD7 PCD6 PCD5 PCD4 PCD3 PCD2
W CWD7 0 0
R/W 0 0 0
R 0 0 0

Figure 9-Register Description

Technical Description
D4 D3 D2
CWD4 CWD3 0
0 0 IRQEN IRQC11 IRQC10
0 0
0
D1 D0
PAD1 PAD0
PBD1 PBD0
PCD1 PCD0
CWD1 CWD0
0
IRQST
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