assembly - opcodes vs. nasm instructions
<p>So I've tried to get into assembly lately and found myself genuinely confused with how NASM works. As far as I understood it is kind of a 'compiler' for assembly that converts (mnemic) instructions to actual machine code. Now I was wondering what the difference between the instructions listed in the NASM manual (www.nasm.us/doc/nasmdocb.html) and the opcodes my machine takes is? Like, let's pretend my Intel processor has some kind of secret opcode that no one knows about and is not listed in the manual, would NASM still be able to assemble it? Or would it just return 'invalid instruction'? And say I knew the machine code format of the opcode, would I be able to insert it manually?</p>