Specifies that serial output of the second UART must be redirected.
$SERIALOUTPUT1 = label
The name of the assembler routine that must be called when a character is send to the serial buffer (UDR1).
The character is placed into R24.
With the redirection of the PRINT and other serial output related commands, you can use your own routines.
This way you can use other devices as output devices.
See the $SERIALOUTPUT example