Microcomputer debug architecture and method

A method of filtering debugging data in a computer system comprising at least one central processing unit and a memory unit coupled to the at least one central processing unit, the method comprising the steps of:

• defining a set of at least three watchpoints in the computer system by defining a set of precondition registers and a set of action registers for each watchpoint;
• defining a set of identical precondition codes to be applied to each watchpoint in the set of watchpoints;
• defining a set of identical action codes to be applied to each watchpoint in the set of watchpoints;
• storing the set of precondition codes in each precondition register in the set of precondition registers;
• storing the set of action codes in each action register in the set of action registers;
• selecting which precondition codes in the set of precondition codes are to be active for each of the at least three watchpoints;
• selecting which action codes in the set of action codes are to be active for each of the at least three watchpoints so that the first and second watchpoints activate a precondition code in the precondition register of the third watchpoint;
• operating the computer system so as to execute a program;
• comparing the debugging data in the computer system with the active precondition codes for each of the at least three watchpoints;
• and
• triggering one of the first and second watchpoints when the debugging data in the computer system satisfies the active precondition codes for the first or second watchpoints and
• triggering the third watchpoint in response to triggering of one of the first and second watchpoints.