It is best if you use code tags not quotes, it is the # next to the quote.
Why
Because the box is smaller, it scrolls, and the forum doesn't scramble your code up so people can copy and paste the code and reproduce your problems.
And mainly because that is what people want around here and it show common decency to comply. After all you are the one asking the questions.
Because on the Uno, Serial.write is non-blocking
Only to the extent of not having a full buffer.