AIM104-COM8 Technical Manual
Jumpers
© 2007 Eurotech Ltd Issue C
15
JP3 - Channel re-mapping to COM addresses
You can individually re-map channels 0 to 3 at the standard COM port addresses.
When these channels are mapped at COM ports they vanish from the group. This
prevents the host seeing them in two places.
If all four are mapped in that way, the group size falls to 32 bytes and channels 4 to 7
begin at the base address.
You should avoid addressing conflicts due to the group decoding overlapping COM
decoding. If there is a conflict, then the group decoding applies and any conflicting
COM decoded channel.
The decoding logic above ensures the minimum use of scarce I/O locations.
JP3
Line
Function when fitted
OPT0
Channel 0 remapped to COM1
OPT1
Channel 1 remapped to COM2
OPT2
Channel 2 remapped to COM3
OPT3
Channel 3 remapped to COM4
OPT4
Disables I/O address decoding for channels 4 to 7
IRQ
Combines interrupts from both quad-UART chips into
one (side A on links below)
Interrupt merging: each quad-UART chip can assert an individual IRQ line,
but in systems where IRQ lines are scarce they can be combined into one
for both chips.
