[asm]
Short for "Assembly." ASM is the language in which ROMs are programmed. If you can learn ASM, your only limit will be the capabilities of the console itself that you're hacking games for. Aside from the .ASM extension after the filename, these are actually no different from any other TXT file. Experienced hackers sometimes prefer this method for distributing their code over making an IPS out of it.

IPS files are more arbitrary because their contents have already been assembled for you. This takes away some freedom in how the patch is used if you're not code-savvy. On the other hand, ASM files show you the author's disassembled code as-is, and allow you to make edits before assembling (applying) it to the ROM like you would an IPS. This is where the xkas assembler comes in. There are other assemblers out there besides this one, but it's the only one I'm familiar with, so we'll use it for this example. I'd reccomend v0.06.

Compiling with xkas works similiarely to soft patching, if you know how to do that (I explained it in my "how to patch IPS files" write-up). After you've downloaded and extracted xkas, place a copy of the SMC and ASM files inside the xkas directory. Give them both the same exact filename, for instance SuperMetroid.SMC and SuperMetroid.ASM. After you've done this, click on the .ASM file, hold the click button down, then "drag" the ASM file on top of the "xkas.exe" file, then release the click button.

This should ask you if you'd like to run xkas.exe. Yes, of course we want to run it. If your set-up is anything like mine, a black window will appear briefly, then disappear like nothing happened. This is normal. Congratulations, you've just compiled an .ASM file. Load the SMC in your emulator of choice, and the ASM should have taken effect. Unlike soft patching, this does edit the ROM file itself, so be sure to use back-up copies in case something goes wrong.