Nios® II Software Developer Handbook

ID 683525
Date 8/28/2023
Public
Document Table of Contents

9.5.5. Invalid Instructions

An invalid instruction word contains invalid codes in the OP or OPX field. For normal Nios® II core implementations, the result of executing an invalid instruction is undefined; processor behavior is dependent on the Nios® II core.

Therefore, the software exception funnel cannot detect or respond to an invalid instruction.

For more information about how invalid instructions are different from unimplemented instructions, refer to the “Unimplemented Instructions” chapter.

For more information, refer to the " Nios® II Core Implementation Details" chapter of the Nios® II Processor Reference Handbook.