A method, computer-readable medium, and apparatus for debugging a computer program utilizing breakpoints triggered by accessing a rarely used or unused I/O port is provided. Rarely used or unused I/O ports are identified in a computer system and a debugger program is instructed to halt program execution when an access is made to one or more of the identified ports. An instruction for writing to one of the ports is then inserted in the program to be debugged. When the instruction is executed, the debugger program will cause the execution of the program to stop. When the breakpoint is no longer needed, the debugger program is instructed not to halt when an access is made to the I/O port.