When I run this code, I don't get anything on my Serial Monitor.
What baud rate have you got the Serial monitor set to ? Note the baud rate in the code that I posted.
By the way, when I replace the '6' for '-1' I got mirrored question marks instead of squares. This does not solve anything, but maybe it helps someone understanding what goes wrong.
What is wrong is that you are writing control characters to the Serial monitor. Serial.println() some text instead.
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Presumably you want to send it via Serial to Processing but get it on the screen first then you can tackle getting it to Processing.