View source for User:Evie (Torchickens)/Sandbox

Evie's list of things she wants to do, or has recently come across but doesn't know much about. Feel free to add details if you like.
==Timing==
*[https://rgbds.gbdev.io/docs/v0.3.5/gbz80.7 Cycles]
*[https://gbdev.gg8.se/wiki/articles/OAM_DMA_tutorial DMA transfer]: ~160 microseconds
*~FF46 write - began OAM DMA transfer (one byte RAM specified for h (high byte) in RAM pointer that mirrors rDMA/FEXX-9F (you know this))
*"[https://gbdev.io/pandocs/STAT.html LY indicates the current horizontal line, which might be about to be drawn, being drawn, or just been drawn. LY can hold any value from 0 to 153, with values from 144 to 153 indicating the VBlank period]."
*You can only access HRAM while a DMA transfer is taking place.
*"[[RNG correlation (Generation I)|the rDIV register, which itself is incremented at a rate of 16384Hz (~16779Hz on SGB)]]"
*From that RNG correlation article "516 cycles (2.015625 rDIV periods)" - so just say 2/516 (1/258 rDIV) for one cycle.
*[https://gbdev.io/pandocs/OAM_Corruption_Bug.html OAM corruption bug]
*[https://gbdev.gg8.se/wiki/articles/Video_Display Video Display]/VBlank
*[https://www.3bscientific.com/gb/microsecond-counter-230-v-5060-hz-1017333-u8498285-230-3b-scientific,p_813_25740.html Microsecond counter]
*It's more complex than this, but just leave these notes for now.


To-do: Defaults and relationship with Game Boy, GBC, SGB boot ROMs.

==Hexadecimal byte representation of Cryo's real-time RAM writer for writing code using button sequences==

https://archives.glitchcity.info/forums/board-115/thread-7744/page-0.html

Red/Blue EN:

<pre>
2EFE1D5414D523CD
FA3F3DF0F8FE0CC8
F0B237B728F143B9
4228EB4F41865077
4418E4
</pre>

==Catch rate correspondence table (Generation I)==

Red/Blue

<pre>
ID Pokemon Catch rate Held item in Gen 2
00 'M (00) 1D Carbos
01 Rhydon 3C Silver Leaf
</pre>

Exceptions:

Changes to catch rate in games (Thx Bulbapedia):

*In Yellow, starter Pikachu hold Light Ball
*In Yellow, wild Kadabra hold TwistedSpoon
*In Yellow, wild Dragonair hold Protein
*In Yellow, wild Dragonite hold Antidote
*Stadium gift Pokémon hold Normal Box (Round 1) or Gorgeous Box (Round 2)

[https://github.com/pret/pokecrystal/blob/master/data/items/catch_rate_items.asm Converted catch rates] (TimeCapsule_CatchRateItems):

*Catch rate 0x19 becomes Leftovers
*0x2D becomes Bitter Berry
*0x32 becomes Gold Berry
*0x5A, 0x64, 0x78, 0x87, 0xBE, 0xC3, 0xDC, 0xFA, 0xFF all become Berry

How to acquire a Pokémon with any catch rate:

(Tested on Yellow probably works the same on Red/Blue)

*Have in party only special MissingNo. (Kabutops Fossi, Aerodactyl, Ghost), then save/reset
*Manipulate D0C0-1 (W_MONHCATCHRATE). (Probably can do this with [[LWA]])
*Encounter/acquire special MissingNo. (Kabutops Fossi, Aerodactyl, Ghost) and catch it
*The acquired Pokémon will have the catch rate from D0C0-1.


==IR trade pet project==
===Theory===
Use [[I/O|$FF56]] to turn infrared on in two games with [[arbitrary code execution]]. Synchronise the PPU(?) cycles. Use a modified version of the Cable Club code.

In it, have a prompt to keep the Game Boy Colors next to each other for each interaction (press A to start read/write) and have some kind of error prevention if communication fails.

I wonder how practical this is because for Gold/Silver they used IR for different purposes (obtaining decorations, items, Trainer House Trainers).

==Other things==
[https://glitchcity.wiki/index.php?title=User:Evie_(Torchickens)/Sandbox&action=history (Archived as the page gets big)]