Nios II Classic Processor Reference Guide

ID 683620
Date 10/28/2016
Document Table of Contents

2.3.1. Unimplemented Instructions

Some Nios® II processor core implementations do not provide hardware to support the entire Nios II instruction set. In such a core, instructions without hardware support are known as unimplemented instructions.

The processor generates an exception whenever it issues an unimplemented instruction so your exception handler can call a routine that emulates the operation in software. Unimplemented instructions do not affect the programmer’s view of the processor.

For a list of potential unimplemented instructions, refer to the Programming Model chapter of the Nios® II Processor Reference Handbook.