> The assembly code is filled with lots of questionable structures. In general, there are lots and lots of NOP instructions. Some are executed in the code flow, but most are used as padding between code sections.
That's common for machine code written without an assembler but typed directly into a hex monitor (don't know if Invaders was developed that way though). You kept a couple of nops in 'reserve' - usually after branches and returns - so that fixes can be applied without having to move the rest of the code around (which would mean retyping everything).
That's common for machine code written without an assembler but typed directly into a hex monitor (don't know if Invaders was developed that way though). You kept a couple of nops in 'reserve' - usually after branches and returns - so that fixes can be applied without having to move the rest of the code around (which would mean retyping everything).