When debugging embedded software in ROM, the MCU debug-system must use hardware breakpoints for indicating events. Software breakpoints generally cannot be set in ROM.

The flexible feature of Oki's Advantage Microcontrollers that enables debugging through JTAG is the on-chip debug hardware called "embedded ICE." The embedded ICE feature of ARM7TDMI cores supports two hardware breakpoints. As a result, the maximum number of breakpoints that can be set when debugging in ROM is two. This limitation is due to the fact that there are only a few hardware breakpoints available as opposed to numerous software breakpoints that can be set in RAM.