Interestingly enough, Serial.read() does not work like most of us think.
Serial.read() is not blocking, it always returns immediately with a byte 0-255 or -1 if there is no character to read.
From Arduino Reference
Description
Reads incoming serial data. read() inherits from the Stream utility class.
Syntax
Serial.read()
Parameters
None
Returns
the first byte of incoming serial data available (or -1 if no data is available) - int
Wirewrap
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