4.3.1 ROM Emulators

One other type of emulator is worth mentioning at this point. A ROM emulator is a device that emulates a read-only memory device. Like an ICE, it is an embedded system that connects to the target and communicates with the host. However, this time the target connection is via a ROM socket. To the embedded processor, it looks like any other read-only memory device. But to the remote debugger, it looks like a debug monitor.

ROM emulators have several advantages over debug monitors. First, no one has to port the debug monitor code to your particular target hardware. Second, the ROM emulator supplies its own serial or network connection to the host, so it is not necessary to use the target's own, usually limited, resources. And finally, the ROM emulator is a true replacement for the original ROM, so none of the target's memory is used up by the debug monitor code.