Brad Corrupts, a new rom corrupting series

Reaper_Man · Post by **Reaper_Man** » Fri Jul 30, 2010 12:01 am

Sup guys. I know I haven't posted here a lot, but I felt that I should share my youtube series with you guys. Anyway, What I'm doing here is taking NES roms and running them through a Python script that randomly changes bytes in random locations (in PRG ROM). I then take footage from the now corrupted game (10 iterations) and put them on youtube. So far, I have made three which are as follows:

1942
Abadox
Al Unser Jr.'s Turbo Racing

I plan to go through my entire collection when I was a kid. Afterwards I plan on taking various requests. Anyway, I wanted to share my series with you guys for 3 reasons:

1. We all have something in common. We're are all geeks that have a love for the NES and its hardware/software and how it al works etc. I'm certain that you guys will take interest in this. :D

2. Some games I've corrupted does some pretty weird, unexplainable shit and I'm really curious as to why some corrupted games exhibit such strange behavior (outside of the already "normal" corrupted behavior you'd expect) I figure some of you guys could enlighten me. :3

3. I'm hoping someone with hardware access can perhaps run my corruptions on real hardware and look for any discrepancies between hardware and various emulators. In other words, I'm hoping that maybe my corruptions might uncover some hidden secrets tucked deep inside the NES that'll hopefully lead to better and more accurate emulation (and yeah I know it's pretty damn close to perfect anyway, but the more we find out, the more it benefits all of us, right?)

Anyway, take a look, and let me know what you think :D

ccovell · Post by **ccovell** » Fri Jul 30, 2010 5:58 am

I used to do the same thing with random 6-letter Game Genie codes. I would keep track of interesting codes in a notebook and try variations when something would glitch up well.

That's how I found a level select for Journey to Silius and a super-jump & invincibility code for Shadow of the Ninja way back when (1991.)

Yep, I had too much time back in the 9th grade, obviously.

Reaper_Man · Post by **Reaper_Man** » Fri Jul 30, 2010 1:35 pm

ccovell wrote:I used to do the same thing with random 6-letter Game Genie codes. I would keep track of interesting codes in a notebook and try variations when something would glitch up well.

I have very fond memories of doing that as a kid as well. The Game Genie was my favorite NES accessory and the rom corruptions are a bit of a homage to those times.

Dwedit · Post by **Dwedit** » Fri Jul 30, 2010 1:43 pm

When you change a 2 or 3-byte instruction to a 1-byte instruction, that single byte change can do a lot, since it misses the next few instructions, executing junk instead, until it can eventually get back on track. If it misses a jump, call, or return, that's an even bigger effect.

Reaper_Man · Post by **Reaper_Man** » Sat Jul 31, 2010 12:18 am

Dwedit wrote:When you change a 2 or 3-byte instruction to a 1-byte instruction, that single byte change can do a lot, since it misses the next few instructions, executing junk instead, until it can eventually get back on track. If it misses a jump, call, or return, that's an even bigger effect.

Oh I know that (at least the basics of what happens), but there are certain things that happen often and I am trying to figure out why it always shows such similar behavior. My next vid will show a great example of this.

Reaper_Man · Post by **Reaper_Man** » Fri Aug 20, 2010 12:54 pm

Alright guys, new vid is up. This one is for Bandai Golf: Challenge Pebble Beach.

Now pay attention to the first 4 or so iterations. I seem to have run into a very similar.... effect.... the flashing screen with the horizontal lines and such.... what I want to know is, what exactly is going on there, and how come I kept getting that?

Next game to get corrupted: A Boy and His Blob

Post by **tepples** » Fri Aug 20, 2010 1:16 pm

These flashing horizontal lines look like palette writes. Palette writes might happen when VRAM loading code crosses over PPU $3F00-$3FFF. It looks like data lengths might have been corrupted.

Reaper_Man · Post by **Reaper_Man** » Fri Aug 20, 2010 1:35 pm

tepples wrote:These flashing horizontal lines look like palette writes. Palette writes might happen when VRAM loading code crosses over PPU $3F00-$3FFF. It looks like data lengths might have been corrupted.

Interesting. I think it may also have to do with how the game draws the course topography at the top of the screen. At least that was my guess. Would you, or anyone for that matter, want the IPS files to study the phenomena?

Dwedit · Post by **Dwedit** » Fri Aug 20, 2010 2:35 pm

I wonder if Rom Corruption videos would even exist if I hadn't made my particular corruption tool...

Reaper_Man · Post by **Reaper_Man** » Fri Aug 20, 2010 6:09 pm

Dwedit wrote:I wonder if Rom Corruption videos would even exist if I hadn't made my particular corruption tool...

You mean CORRUPT? Probably not, haha, but I happen to use my own tool for corrupting my roms.

Reaper_Man · Post by **Reaper_Man** » Sun Sep 12, 2010 8:04 pm

Well, I made a new video! This time, I corrupt A Boy and His Blob!

Please feel free to like, rate, comment, subscribe, annotate, and discuss in this thread.

artakserkso · Post by **artakserkso** » Tue Sep 14, 2010 8:17 am

I wonder if this is how they made Cheetahmen.

Reaper_Man · Post by **Reaper_Man** » Tue Sep 14, 2010 1:38 pm

artakserkso wrote:I wonder if this is how they made Cheetahmen.

Probably. Funny thing is though my vids are more entertaining, haha.

Actually corrupting Action 52 would probably FIX most of the games.

Post by **Memblers** » Tue Sep 14, 2010 3:00 pm

The sudden (and short-lived) rocket blast-off with the umbrella was pretty funny.

Reaper_Man · Post by **Reaper_Man** » Thu Sep 16, 2010 2:38 pm

Memblers wrote:The sudden (and short-lived) rocket blast-off with the umbrella was pretty funny.

I personally thought the one where he isn't wearing any pants was more amusing.