.b number [addr]
The .b command sets the baud rate for the debugging port (COM2).
number
Specifies the baud rate. It can be one of the following values: 150, 300, 600, 1200, 2400, 4800, 9600, or 19200. Because the default radix for the debugger is 16, you must type t after the number to indicate a decimal value.
addr
Specifies 1 for COM1 or 2 for COM2; anything else is taken as a base port address. If there is no COM2, the debugger checks for COM1 and then for any other COM port address in the read-only memory (ROM) data area to use as the console.
The following example sets the baud rate to 1200:
#.b 1200t