Control characters display format in hyperterminal

Question

I am working with a serial device. On data receive, i am getting heart symbol along with actual data.
Then i decoded the ASCII value and found that it is equivalent to <ETX> (End of text)
Why it is showing heart symbol for ETX??
What would be the display character for STX?? Is there any list available other control characters??

Answer 1

http://en.wikipedia.org/wiki/Code_page_437#Interpretation_of_code_points_1.E2.80.9331_and_127

Why does SO think the above link is 0 characters long?