title: does 64 bit code take up more storage space that 32 bit code?
body: <p>Sorry, I'm not long on S/O and a total newb at asm.</p>
  
  <p>I've been reading over the Intel, Amd and nasm docs, ref.x86asm.net, sandpile.org, and wiki.osdev.org.  </p>
  
  <p>One thing I can't quite appreciate is whether:</p>
  
  <ol>
  <li>64 bit instructions are actually bigger (in long mode) than 32 bit instructions (in protected mode) because of prefixes... or whether the instructions are the same width?</li>
  <li>And when the operands are given, they are often zero-padded (automatically), but is this done by the assembler at compile time or the processor at runtime?</li>
  </ol>
  
  <p>Sorry if this is really obvious...</p>