Instructor is a 32 bit instruction set auditor. By sequentially executing every 32 Bit OpCode, one can find instructions that might have adverse effects on operating environments. For example, Instructor was used to find the non-privileged halt instruction.
You can download it from the following link: https://packetstormsecurity.com/files/download/10636/instructor.c
Source: https://packetstormsecurity.com/files/10636/instructor.c.html