View source for Cart-swap arbitrary code execution

{{Major glitches}}
'''Cart-swap arbitrary code execution''' is an exploit for Game Boy or Game Boy Color games running on a physical Game Boy Color or SNES; in which the player swaps one cartridge with another while the system is still running to transfer data or execute arbitrary code on the other.

This technique was developed by ISSOtm and TheZZAZZGlitch, inspired by MrCheeze's [https://www.youtube.com/watch?v=xayxmTLljr8 Magi Nation exploit] in which he executed arbitrary code in Magi Nation for Game Boy Color with data leftover from Pokémon Red's [[255 Pokémon glitch]].

It was originally nicknamed the "Luigi exploit" because the player can force the game to do 'absolutely nothing' until the cartridge is swapped; a reference to the "Luigi wins by doing absolutely nothing" meme.

Cart-swap arbitrary code execution may be set up with another form of arbitrary code execution, such as via 8F.

During cart swap arbitrary code execution, interrupts usually must be disabled to prevent the game running code from the ROM which doesn't exist when the cartridge is removed.

==Applications==
*Force load a game, including CGB games in DMG mode. The game may be loaded with the wrong palette.
*[https://www.youtube.com/watch?v=SL_Zuc0tlvo Warp to the credits in Super Mario Land 2]
*[https://www.youtube.com/watch?v=BNyDmZlbsNI Activate TCG debug menu]

===Booting up a game without setting the palette===

Set up 8F arbitrary code execution and prepare your items pack as such:

8F

Any item

TM43 x22

Moon Stone x1

Master Ball x147

Antidote x121

Escape Rope x176

Fire Stone x250

Parlyz Heal x21

Guard Spec. x32

TM45 x175

Great Ball x111

Carbos x1

TM33 xAny


Bytes:

<code>5d 01 01 01 f3 16 0a 01 01 93 0b 79 1d b0 20 fa 0f 15 37 20 f5 af 03 6f 26 01 e9 01</code>

ASM:

<code>
di 
ld d,0a
ld bc,9301
dec bc
ld a,c
dec e
or b
jr nz,D328
rrca
dec d
scf
jr nz,D328
xor a
inc b
ld l,a
ld h,01
jp hl
</code>

Upon using 8F, the game will hang for a few moments. During that time quickly pull out the cartridge and replace it with another cartridge (but not a game that only works on Game Boy Color or later) and it will boot up, possibly with a palette based on the palette while playing Pokémon Red.

===Force boot in Game Boy mode===
Run the following code. (Created by TheZZAZZGlitch)

<code>F3 16 0B 01 FF FF 0B 79 B0 20 FB 15 20 F5 C3 00
01</code>

===Force boot game in GBC mode===
Run the following code. (Created by TheZZAZZGlitch)

<code>F3 16 0B 01 FF FF 0B 79 B0 20 FB 15 20 F5 3E 11
C3 00 01</code>

===Super Mario Land 2 credits===
Refer to [[executing large programs with arbitrary code execution]] and write the following code to execute with your execution method. (Created by TheZZAZZGlitch)

<code>F3 16 0B 01 FF FF 0B 79 B0 20 FB 15 20 F5 21 00
D0 11 E5 01 0E FF 1A 22 13 0D 20 FA AF EA 30 D0
21 37 D0 3E 3E 22 3E 01 22 3E EA 22 3E D5 22 3E
A2 22 3E C3 22 3E 1C 22 3E 02 22 21 E0 D0 3E 21
22 AF 22 3E D1 22 3E 01 22 AF 22 3E 1F 22 3E AF
22 3E 22 22 3E 0B 22 3E 79 22 3E B0 22 3E 20 22
3E F9 22 3E C3 22 AF 22 3E D0 22 C3 E0 D0</code>

Execute it only after turning off Super Mario Land 2 at the title screen. This will cause a white screen to appear, but after pressing Start you can play a stage to instantly trigger the credits.

===Pokémon TCG (EU) debug menu===
Created by ISSOtm. For the English European version. This does not work on US versions.

Steps:

1) Use a Game Boy program writing exploit to write data.

In this example we write [http://forums.glitchcity.info/index.php?topic=7773.0 offgao's memory editor] known as "Pocket Computer" ported by cryo and then use it as a tool to write the data for the cart-swap program.

For this example we write the Pocket Computer to data at DA80-DB7C using a modified version of TheZZAZZGlitch's method of writing and executing large programs.

To access it with we require the following items:

Items:


Bicycle

8F

X Accuracy x97

Burn Heal x126

Paralyz Heal x15

HP Up x15

Ice Heal x15

Potion x134

TM34 x20

TM15 x46

Leaf Stone x52

Great Ball x201

TM10 x1

TM18 x46

(any non duplicate item) x (any)

TM34 x128

(any non duplicate item) x (any)

TM19 x46

TM34 x0

(any non duplicate item) x (any)

Item C3 ("H") x 128

TM18 x 201

Method for setting up Pocket Computer:

1) Swap TM18 x46 with TM15 x46, use 8F and jump off a ledge to walk through walls. This allows the player to walk on impassable tiles, so that they may access all coordinates ranging from hex:00 to hex:0F.
There will now be a TM34 x21 instead of x20.

2) Swap TM18 and TM15 back, swap TM34 below Potion with TM34 x128 and use Bicycle. The program is now in 'entering mode', and upon using 8F one byte is written to address DA80 (and onward for each use) with its value depending on your X and Y positions where the Y position represents the high nybble and the X position represents the low nybble. For example, a coordinate of y=0C, x=09 would write a C9 (ret).

3) Swap TM18 with TM19 and TM34 with TM34 x0, enter DB00 bytes. To run the created code, add item c3 x 128 and TM18 x201 to items 3 and 4.

Coordinates map:

[[File:Route 1 coordinates.png|300px]]

Data you need:

<code>
@DA80:
07 F6 01 00 FE 01 18 1F FF 00
00 00 00 00 00 00 00 00 00 00
00 00 F6 F7 F8 F9 FA FB FC FD
FE FF 60 61 62 63 64 65 66 01
00 DA C5 0B 0B 16 12 21 AA C3
CD 4F DB 03 C5 01 0A 00 09 C1
15 20 F3 C1 3E ED EA D3 C3 3E
FF E0 B7 76 C5 CD 31 38 C1 F0
B5 FE 02 C8 FE 03 20 03 00 C5
C9 FE 40 20 01 0B FE 80 20 01
03 FE 20 20 06 21 F0 FF 09 44
4D FE 10 20 06 21 10 00 09 44
4D FE 24 20 06 21 00 FF
 
 
@DB00:
 
09 44 4D FE 14 20 06 21 00 01
09 44 4D 16 00 FE 88 20 02 16
FF FE 48 20 02 16 01 FE 28 20
02 16 F0 FE 18 20 02 16 10 60
69 FE 44 20 08 F5 3A F5 2A 32
F1 77 F1 FE 84 20 0A F5 2A 18
00 F5 3A 22 F1 77 F1 44 4D 7A
A7 28 03 0A 82 02 C3 AA DA 3E
7C 22 3E 7F 22 78 CD 6A DB 79
1E 1F CD 6A DB 3E E3 22 0A CD
6A DB 3E 7C 22 C9 F5 CB 37 CD
71 DB F1 E5 26 DA E6 0F C6 96
6F 7E E1 22 C9
</code>

After you finish writing the data, save the game and write the following bytes using the memory editor you just created:

<code>
@DF00 :
21 F8 DF 36 01 2E 11 0E 83 06 03 CD 8A 05 C3 83
FF 3E CA E0
 
DF14-DF50: 00
 
@DF51 :
21 83 FF 36 C3 23 36 00 23 36 DF C3 8D 01 21
00 C0 01 00 1F C3 E3 03 21 00 C0 01 00 1F C3 E3
03
 
@D53B
3E 10 E0 FF 07
E0 00 76 00 3E 01 E0 FF 76 00 21 50 01 11 14 DF
06 3D CD B7 06 21 1F DF 36 68 23 72 C3 14 DF
 
@D322 :
C3 3B D5
</code>

Sadly you can't save now if the trick doesn't work the first time as the data in the DFXX region isn't kept after you save and reset.

Use 8F again and then swap the cartridge with a European version of Pokémon Trading Card Game and press any button. The game should boot to Pokémon Trading Card Game with Red/Blue's palette and you should be able to access the debug menu by choosing 'continue by diary'.
==External links==
*[http://forums.glitchcity.info/index.php?topic=7722.0 Thread on Glitch City Laboratories forums]
==YouTube video==
{{YouTube|SL_Zuc0tlvo|TheZZAZZGlitch}}
[[Category:Generation I glitches]]
[[Category:Generation II glitches]]
[[Category:Recurring glitches]]
[[Category:Arbitrary code execution]]