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Generation I Glitch Discussion

Mysterious map FE (Pokémon Yellow) - Page 1

Mysterious map FE (Pokémon Yellow)

Posted by: Torchickens
Date: 2014-10-12 19:43:26
Map FE looks just like a wrong warp Glitch City. Its appearance can vary, but I wasn't able to change it with 01xxB4D3 01xxB0D3.

When you enter it the game typically freezes. Pretty unremarkable. I thought there was no way to work around this, but when I looked its level-script pointer (map script) was 0E DC (or DC0E in big endian). This is in WRAM in the middle of boxed Pokémon data!

Specifically, DC0E is the first experience byte of Pokémon 12. This means with a total experience of 00 C9 (51546) or 00 00 C9 (201), you can just ret the level script pointer.

When I did this and entered map FE through an expanded items pack (or you can just enter the codes 01FE64D3 01C90EDC and go through an exit mat), the cycling music played and I warped again to map:99h (99, coincidence?), which was fortunately valid; it's a house in Fuchsia City. I also lost the Pokédex for some reason. The side effects of the perpetual spinning glitch happened too. I was forced to spin around while I walk and tiles had bits of a spinning tile on them.

I wonder why the things in the last paragraph happen. I hope that the level script pointer wasn't just DC0E by coincidence. When I got warped to the Fuchsia City house, D364 became FE. This essentially traps you, but you can alter it with an expanded items pack, so you can keep the side effects.

I can't think of a way you could pull of arbitrary code with this, but custom map script arbitrary code is probably more convenient for ACE without a hard to get bootstrap.

Edit: I got glitched Fly destinations, that lead to me glitching my name and box-set somehow and causing the automatic item selection effect. I wonder if that works like Super Glitch. I also messed up the events near the beginning of the game. Oak is outside the lab like when you do (coincidentally) the dokokashira door glitch. Talking to him makes him tell you not to go out, and causes a "!" box to appear above Red's head, but nothing else happens. There is a copy of Oak in the lab who just says "?". I can get a starter Pokémon again, but can't leave the lab, the game locks up before the Rival battle.

Re: Mysterious map FE (Pokémon Yellow)

Posted by: camper
Date: 2014-10-12 23:40:38


Edit: I got glitched Fly destinations, that lead to me glitching my name and box-set somehow and causing the automatic item selection effect. I wonder if that works like Super Glitch.


It works exactly like Super Glitch items. You can get a hooked Metapod encounter (or other Pokemon if your glitch name is long enough)

Re: Mysterious map FE (Pokémon Yellow)

Posted by: luckytyphlosion
Date: 2014-10-13 12:43:09
For me, most of the times Flying to another place (by changing tileset to 0), would crash the game, however some times, I would get a ZZAZZ battle. After the battle, I checked my PC, and I was on Box 1, even though I was on Box 4 before. The Box Counter overflowed, and all my Pokemon inside were corrupted. At least I got Box Item Underflow (Kappa).

Interestingly, entering Sabrina's Gym crashes. This is because most of the bottom items in Item Underflow correspond to warps  from an inside map to an inside map (well, there's probably a better explanation, but that's what I'm assuming), and those items were all corrupted. (the same thing happens to Silph Co.)

Another thing I forgot to add, any map with trainers crashes the game.

Re: Mysterious map FE (Pokémon Yellow)

Posted by: camper
Date: 2014-10-13 23:36:36
That's strange, since ZZAZZ won't ever corrupt the box Pokemon.

Re: Mysterious map FE (Pokémon Yellow)

Posted by: luckytyphlosion
Date: 2014-10-14 15:09:12
The box could have been corrupted by warping to the glitch city.

Re: Mysterious map FE (Pokémon Yellow)

Posted by: Torchickens
Date: 2014-10-14 16:59:40

The box could have been corrupted by warping to the glitch city.


Exactly (according to memory viewer). Both the stored Pokémon and items got corrupted for me.

I got 212 stored items and 0 PC Pokémon after the glitch. Originally I was using box 3 but it changed to box 1. I changed to box 3, deposited a Pokémon (I had 6) then changed back to box 1 and there was '1' Pokémon in that box, but data for more than one. The names of these Pokémon were the original names for my Pokémon in box 3, but their data had been corrupted. The Rattata in box 1 was now a glitch Pokémon hex:D3/Missingno. hex:38 hybrid with Flamethrower, Substitute, Cut and Toxic, among other corruptions.

Originally my options included PROF. OAK's PC and PkMn League, but these were removed after the glitch, meaning the menu looked like this:

BILL's PC
YELLOW's PC
LOG OFF


Interestingly, entering Sabrina's Gym crashes. This is because most of the bottom items in Item Underflow correspond to warps  from an inside map to an inside map (well, there's probably a better explanation, but that's what I'm assuming), and those items were all corrupted. (the same thing happens to Silph Co.)

Another thing I forgot to add, any map with trainers crashes the game.


Is there any way to fix this problem? I can't enter the Hall of Fame without a freeze :/, and I wanted to glitch up the box options like the picture below (occurs when you have Bill's PC, your PC and log off and PkMn League). I have no reason to do this other than to see if it's possible with no cheats and document a new glitch technique.

[img]http://i5.minus.com/iR0wb3Mw6Dy9Q.png[/img]



Interestingly, entering Sabrina's Gym crashes. This is because most of the bottom items in Item Underflow correspond to warps  from an inside map to an inside map


Probably not true. Celadon City gave me a freeze. Additionally, I used 01765DD3 while entering a door in an outside map and I successfully warped to Hall of Fame but the game froze, even though I was under the impression this was an outside map to an indoor map. Also, Route 3 is messed up. It didn't exactly freeze for me, but made glitch music and made it so I couldn't open the menu (though I could move).

Via BGB debugger, I know that the map bank (for executing the level-script) remains the same.

I broke the encounter system. Even using the code 01xx58D0 caused the controls to lock-up and nothing to happen. I fixed this by changing boxes and resetting, however, this did not fix the messed up maps problem.

Some cool other corruptions (ignore the border, it was an emulator bug):

[img]http://i3.minus.com/ibvUIrzl5Ghjh0.png[/img] - Glitch coins [img]http://i4.minus.com/ibmyMnHd9q98v3.png[/img] - Glitch fossil [img]http://i6.minus.com/iGIAJWPWkAUyh.png[/img] - Glitch fossil's summary

I want a fossil Mew personally, but I'm going to check if any glitch items count as fossils.

Re: Mysterious map FE (Pokémon Yellow)

Posted by: Stackout
Date: 2014-10-15 14:59:09

I want a fossil Mew personally, but I'm going to check if any glitch items count as fossils.


Regarding glitch fossils, I've just checked the disassembly.

In normal play, the Cinnabar scientist will only take the valid fossils (null-terminated list of item identifiers at $75d68 (1d:5d68)).

If you somehow patch the code and get the Cinnabar scientist to take something else, you'll get Aerodactyl.

However, if you set bit 0 and unset bit 1 of $d7a3 (so, if $D7A3 ends in $1, $4, $5, $8, $9, $C or $D, or is above $F and ends in $0), then talking to the scientist will give you a Pokémon, which has the identifier corresponding to the value of $D710.

BTW, I'm going off R/B memory offsets here, as I can never remember if you subtract 1 or add 1 to the R/B offsets to get the Yellow offsets…

Re: Mysterious map FE (Pokémon Yellow)

Posted by: Torchickens
Date: 2014-10-15 16:15:46
OK, thanks for that info. Shame he can't take anything else/you'd always get Aerodactyl.

Re: Mysterious map FE (Pokémon Yellow)

Posted by: Torchickens
Date: 2014-11-08 13:05:05
I asked TheZZAZZGlitch if there was a way to fix the map problems, and he explained why they happened. Apparently the name of map FE is too long and corrupts 'script' bytes for certain maps like D5F0 (Pallet Town) and D5F3 (Viridian City). (Thanks for that ZZAZZ)

He said there was no way to fix this, but to a certain extent I disagree. Your stored items get corrupted, and D5F0 seems to be close enough to alter with an items pack of 212 (D4) stored items, which I got from map FE.

Specifically D5F0 should be represented by item 92, according to:

D5F0 = D539 + i + i-1

These scripts are used for things like Professor Oak stopping you and the old man catching a Pokémon. Incidentally, the original old man script from Red/Blue exists in Yellow. Perhaps it's unused because I only remember the script of him failing to catch the Pokémon.

I am currently combing through invalid scripts for useful stuff. However, I know what I find may prove not to be too useful though if the script is taken from the memory.

Highlights:

Pallet Town (D5F0)

1c, 1e, 22 (changes music bank to 00), 35 - (changes music bank to 08), 3f, 47
4d, 51, 58 (causes a Glitch City), 63 (causes a Glitch City), 67, 6C, 75 (makes glitch music), 79

"Oak through walls" may be possible with the valid scripts if it works like Brock through walls.

Pewter City (D5F6)

21: Causes constant walking on the spot and a 'random' effect.

[img]http://i7.minus.com/iSBDxMgkn2p3R.png[/img]

When I stood here eventually I got sent to the Safari Zone and either I'd immediately fly to a Glitch City, get an infinite sent to the Safari Zone loop, just get sent to the Safari Zone once with no noticeable effects, or trigger one set of side effects from this very own glitch (losing the Pokédex and PC options and the perpetual spinning effect).