With NOP-Fills, the reliability of a system in case of a disturbed instruction pointer can be improved in some cases. The entire program memory that is not used by the program code is filled with No-Operation (NOP) instructions. In machine code a NOP instruction is often represented by 0x00 (for example, Intel 8051, ATmega16, etc.). The system is kept in a defined state. At the end of the physical program memory, an instruction pointer error handling (IPEH IP-Error-Handler) has to be implemented. In some cases this can be a simple reset.