Uploaded January 2015 | Updated September 2026, 3 weeks ago

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Around one year ago I made a video very similar to this one, and it's been one of my most successful videos so far so I thought I'd try it again!
Here is the old video: youtube.com/watch?v=mVTTXT_vxAc

Description:

A lot of the game's data passes through the routine at 0xB5 when it needs to be moved between registers. But we can easily apply a small hack to this routine so that each byte of each "chunk" of data has a predetermined chance of being overwritten by a completely random number. Obviously, the higher the chance we make it be, the more glitched the game will look, but the randomness of the process makes it so fun and unpredictable!

HEX (insert this at address 00B5): CD 5C 3E FE XX* 38 07 CD 5C 3E 23 12 18 02 2A 12 13 0B 79 B0 20 EA C9
0x100 - 0xXX out of 0x100 bytes get glitched

ASM:

GlitchedCopyData: ; 00B5

call GenRandom ; call 3E5C (generates random 8-bit number in a)
cp XX ; 0x100 - 0xXX out of 0x100 bytes get glitched
jr c, .dontGlitch

.glitchByte
call GenRandom
inc hl
ld (de),a
jr, doneGlitching

.dontGlitch
ldi a,(hl)
ld (de),a

.doneGlitching
inc de
dec bc
ld a,c
or a,b
jr nz,GlitchedCopyData
ret