Without this, the debugger spontaneously fails! 1 - Install mdk315b 2 - Replace the files: \\Keil\\ARM\\BIN\\ARM.DLL with one from mdk305a\\Keil\\ARM\\BIN\\ARM.DLL \\Keil\\ARM\\BIN31\\ARM.DLL with one from mdk305a\\Keil\\ARM\\BIN30\\A