The Opcode Quiz

| tags: asm web

This is a gamified extension of the x86 opcode mnemonic generator. Playing should, hopefully, be self-explanatory.

See bottom of the page for technical details on, e.g., which kind of dialect is exactly considered "real".

The Opcode Quiz

Score (for ):

Correct: 0/0

That opcode is…

Your answer was…

Previous questions:


    The idea of turning the x86 opcode mnemonic generator into quiz form was suggested by kmc on #esoteric.

    Technical Details

    The instructions considered "real" have been collected mostly by extracting them from the GNU Binutils sources, with the following exceptions. The x86 dialect is that of NASM (latest daily snapshot, as of this post). The 6502 opcodes come from the cc65 compiler's ca65 assembler.

    The real opcode extraction process (fancy word for grep/cut/sed pipelines) is not guaranteed to be flawless. Do contact me in case of any egregious examples of accepting a strange word / not accepting a perfectly good opcode.

    As with the x86 opcode mnemonic generator, the fake opcodes are generated by sampling from a fourth-order character n-gram model, trained using the SRILM language modeling toolkit. As the n-gram models have some problems accurately modeling sentence (opcode) lengths, allowed fake instructions are artificially restricted to be not shorter or longer than any real instruction.