1. A method of embedding messages into a program counter trace stream comprising the steps of: receiving program counter information; outputting a program counter trace stream corresponding to the program counter information; writing a message unrelated to the program counter information into a message buffer; asserting a request to insert signal after the message is completely stored in the buffer; inserting the message stored in the buffer into the program counter trace stream upon an insert signal; and outputting a program counter trace stream with the inserted message.