Pokémon Yellow rotating Porygon save file

Notes: While coding this things went wrong and a couple of the sprites are unused (one of them was glitched and did not display properly). This program works but there are various things I stubbed out/overwrote.


Q&A:

*Where is the save file?:

Here ^^
https://drive.google.com/file/d/1DoI4gl8o1D3wQEWsbcGY5B53tzlcIaim/view?usp=sharing

*What is this?:

A way to display 7 custom Pokémon sprites on loop, even if they're not in the game.

*How to start it:

-Talk to the man in front of Red to view the rotating Porygon

-(Optional) Use ws m in the bag to view just one sprite of it

-(Optional) Use 4F to set the palette to Virtual Boy mode. Though you can do the two above without setting the palette. (edit: I'll need to update the save file again sorry, as this also changes the map script and freezes the game after closing the menu on an unknown opcode at the moment. It might not freeze on Nintendo 3DS Virtual Console because they ignore unknown opcodes. Either way, a GameShark code 010E5CD3 will fix that for now by setting the palette without 4F).

*How did you make it rotate?

You can play around with the skew feature on Paint, and for the upside down Porygon I rotated some parts while keeping the rest and made some small other changes.

*How do I add sprites?:

To import sprites, use/follow the steps on the readme of the sprite import tools link on my old Google Sites.
https://sites.google.com/site/torchickens2/glitching-tools

You don't have to do a rotation demo, for example, you could add a slideshow of seven or more unreleased Pokémon, or Gen II+ Pokémon, etc.

This only works for compressed sprites (not uncompressed sprites) and if you're editing the Porygon rotation demo save,
a maximum of 0x015A bytes long (as in the ld bc,015A below) (unless you rework the code).

Editing the code can be done by opening BGB debugger and going to the memory addresses below.

To do that,

1. Run BGB emulator with Pokémon Yellow and the save file (the easiest way is to rename the save file the same name as the ROM and have it in the
same folder/directory). Right click on the window and go to other>debugger.
2. Right click again on the new debugging window and select "Go to..."
3. Choose one of the below memory addresses (such as da80, dd50, dac5, etc.) you want to inspect by typing da80 and clicking OK, etc.
DAC5-DBE4 is the first picture, which you can replace with your own after following the steps below and copy/pasting the bytes.
For the save file, it's a bit more complicated as the save file is normally locked.
On the debugger, click debug, then access breakpoints, then add an entry for address range A000-BFFF (the value doesn't matter) with on write checked.

Attempt to save the game. Now, BGB should pause at a point where the save file is open. This time go to 2:(save file pointer) such as 2:A000 for the picture 2,
2:A15A for the picture 3, etc. You can then right click and modify code/data, then paste the bytes you got using your hex editor after making a new compressed
sprite with the sprite import tools.


*Changing the 'Virtual Boy palette': Go to DA65 and change the 0E to another ID to get another possible palette after using the 4F in your bag. Or directly,
you can just edit D35C but this won't change how 4F works. As another example, f0 d3 ea 5c d3 c9 at DA64 would give a (pseudo)random palette after using 4F.
Note 4F won't work on Nintendo 64 GB Tower (and I haven't tested it there for this concept either).

da80 (da81-dac4)
> print box of compressed picture file, next text box at DD00.

dd50
> declare dimensions/sprite source (picture 1) ; dimensions = 56x56 ($77), pointer=dac5

dac5-dbe4

> Picture 1, Gen I compressed picture file

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

(1. facing left)

dd00 (dd01)
> ASM (text code) for picture 2 - Open bank 2 of save file, copy $015A bytes of data from 2:A000 to dynamically change dac5. Next text box is now at DD1F.

db 08
ld a,02
ld (4000),a
ld a,0a
ld (0000),a
ld bc,015a
ld de,dac5
ld hl,a000
call 00b1
ld a,1f
ld (dac2),a
jp da81

(2. diagonal bottom left)

dd1F
> ASM (text code) for picture 3. Next text box is now at dd60

db 08
ld a,02
ld (4000),a
ld a,0a
ld (0000),a
ld bc,015a
ld de,dac5
ld hl,a15a
call 00b1
ld a,60
ld (dac2),a
jp da81

(3. facing down red/blue sprite)

dd60
> ASM (text code) for picture 4. Next text box is now at dd60.


A15A +15B=A2B5 (picture 4)
DD60 +1F=7F (next text code)

db 08
ld a,02
ld (4000),a
ld a,0a
ld (0000),a
ld bc,015a
ld de,dac5
ld hl,a2B5
call 00b1
ld a,7f
ld (dac2),a
jp da81


(4. diagonal bottom-right)

DD7F


''' +15B = A410 (picture 5)
DD9E (next) (note I used 7.pic because 6.pic wouldn't display properly)

db 08
ld a,02
ld (4000),a
ld a,0a
ld (0000),a
ld bc,015a
ld de,dac5
ld hl,a410
call 00b1
ld a,9e
ld (dac2),a
jp da81

(5. another intermediatry between bottom-right and top-right unneeded on hindsight)

DD9E
''' +15B = A56B (picture 6)
DDBD (next)

db 08
ld a,02
ld (4000),a
ld a,0a
ld (0000),a
ld bc,015a
ld de,dac5
ld hl,a56b
call 00b1
ld a,bd
ld (dac2),a
jp da81

(6. diagonal top-right)

DDBD
''' +15B = A6C6 (picture 7)
DDDC (next)

db 08
ld a,02
ld (4000),a
ld a,0a
ld (0000),a
ld bc,015a
ld de,dac5
ld hl,a6c6
call 00b1
ld a,dc
ld (dac2),a
jp da81

(7. facing up 'upside down Porygon')

DDDC
''' +15B = A821 (I stored another copy of the picture 1 here, it works though inefficient (as is the rest of this program))
DD00

db 08
ld a,02
ld (4000),a
ld a,0a
ld (0000),a
ld bc,015a
ld de,dac5
ld hl,a821
call 00b1
ld a,00
ld (dac2),a
jp da81

(8. copy of picture 1 'facing left', loop to picture 2, and repeat indefinitely))