Method and apparatus for debugging embedded systems having read only memory

A tangible computer readable medium having program instructions for debugging an IC, comprising:

• program instructions for defining an on-chip RAM memory to function as ROM boot memory;
• program instructions for detecting initiation of a debug mode;
• program instructions for transitioning the on-chip RAM memory to function as a RAM memory while in debug mode to accept writes to the on-chip memory;
• program instructions for modifying contents of the on-chip RAM memory;
• and
• program instructions for terminating the debug mode and the modification capability of the on-chip RAM memory.

An integrated circuit (IC), comprising:

• a microprocessing unit (MPU);
• a memory region acting as a read only memory in a first state;
• and
• a Joint Test Action Group (JTAG) debug module able to detect a breakpoint causing an interruption of a processing sequence executed by the MPU, the JTAG debug module is in communication with the memory region, the JTAG debug module having write control circuitry to control writes to the memory region, the write control circuitry issuing a signal enabling the memory region to transition to a second state where the memory region acts as a RAM memory to accept data from the MPU in response to the breakpoint occurring.