802Ah - Modem I/O BASE Register 0
7
6
A7
A6
0
0
802Ch - Modem I/O BASE Register 1
7
6
A15
A14
0
0
The Modem I/O Base registers determine the
base address of the I/O range used to access
function specific registers. These registers allow
the function's registers to be placed anywhere in
the host's I/O space. I/O Base 0 contains the
low order byte (A7-A0) and I/O Base 1 contains
the high order byte (A15-A8). Since the modem
function requires 8 I/O locations, bits 2-0 of I/O
5
4
A5
A4
0
0
5
4
A13
A12
0
0
Base 0 are always 0. Since only A15 to A4 are
decoded by the controller (64K address space),
it is up to the host to resolve any conflicts with
addressing above 64K.
These registers are still accessable even if the
"Enable Base and Limit" bit in the MCOR is
cleared (0).
89
3
2
A3
0
0
0
3
2
A11
A10
0
0
1
0
0
0
0
0
1
0
A9
A8
1
1
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