The funny thing is, if they merely cut the password index to use 3 bits instead of 4, then the values that crash the game wouldn't be possible. Some passwords would reset the game, but they wouldn't crash an emulator completely, and it wouldn't be this big weird mystery to dig into lol

11/11

You can change the starting area with the password
"000000 00000x 000000 00000x"
where x is 0-9, or A-F for values 10-15.

"B" is level 11, which is what I used in my example fact. "F", level 15, will also crash emulators.

In actual hardware they will behave in a way unique to that hardware.

10/11

People assume its intentional by nintendo to punish foul language

How else is the game breaking out of its virtual confinement and crashing the emulator itself?

It's scary spooky to people because they don't understand whats happening and it doesn't seem to behave like a game normally should

9/11

There is a well-known password that crashes NES Metroid-
"ENGAGE RIDLEY MOTHER FUCKER"

This crashes for the exact same reasons I've talked about. I just took this password and stripped out all of the fluff data until all that was left was the actual source of the crash- the level selection.

8/11

Illegal instructions can behave completely differently between 2 different processors, just depending on how they were made.

So what is an emulator supposed to emulate?
They can try to simulate what a specific manufactured chip would do, maybe.

But most emulators will just crash by default

7/11

If 2 manufacturers make processors that use the same instruction set, they can make them in different ways as long as they appear to behave the same with the *legal* instructions. So any valid code on one will run on the other.

But illegal instructions? That's the wild west.

6/11

The console is running machine code that it wasn't intended to. For level indexes 11 and 15, it ends up running into what's called an "illegal opcode"

That is a machine instruction that isn't officially supported and has no defined meaning for the processor.

5/11

This is because they just happen to run the opcode (machine code) "00", which is the "BRK" or "Break" operation. This causes an interrupt, or in other words is treated like the reset button was hit on the console. Purely by accident.

However.
Indexes 11 and 15 are special.

4/11

A bad index causes it to look outside of the table to junk data, causing the code to jump to a point it's not supposed to jump to. Now the processor is executing commands that were not programmed or intended.

Coincidentally, *most* of the bad indexes end up simply resetting the game properly

3/11

This means numbers 0-15 can be used (0000-1111 in binary) to index into the table. No bounds checking is performed, because they just assume you have a valid password. (The password uses a checksum, so you can't just type one at random.)

So it looks in the table for an address to jump to.

2/11

It's size shifters all the way down

I need like a million new people per day to help satiate it

So addicting that you both can't help yourselves, even when I warn about its potent shrinking effect~

Soon she'll be making love to my cock with her full body, lapping away at my pre. And you? Barely adding to the taste of the nectar~

I don't feel obligated per se, but I do like the praise and worship :3