I have this Data Bytes in "bank 1":
Background:
.db $00,$00,$00,$00,$00,$25,$25,$25,$25,$25,$25,$25,$25,$25,$25,$25
.db $25,$25,$25,$25,$25,$25,$25,$25,$25,$25,$25,$00,$00,$00,$00,$00
.db $00,$00,$00,$00,$00,$25,$25,$25,$25,$25,$25,$25,$25,$25,$25,$25
.db $25,$25,$25,$25,$25,$25,$25,$25,$25,$25,$25,$00,$00,$00,$00,$00
.db $00,$00,$00,$00,$00,$25,$25,$25,$25,$25,$25,$25,$25,$25,$25,$25
.db $25,$25,$25,$25,$25,$25,$25,$25,$25,$25,$25,$00,$00,$00,$00,$00
.db $00,$00,$00,$00,$00,$25,$25,$25,$25,$25,$25,$25,$25,$25,$25,$25
.db $25,$25,$25,$25,$25,$25,$25,$25,$25,$25,$25,$00,$00,$00,$00,$00
.db $00,$00,$00,$00,$00,$25,$25,$25,$25,$25,$25,$25,$25,$25,$25,$25
.db $25,$25,$25,$25,$25,$25,$25,$25,$25,$25,$25,$00,$00,$00,$00,$00
I read these bytes and write them in the PPU's background every frame.
However when I try to change them trough code nothing happens
I wrote this code at bank 0 to do it but it does not work.
ReadB:
LDA $4016
AND #$01
BEQ ReadBDone
LDA #$02
STA Background
ReadBDone:
I tried using a debugger to see what was going on and found out that once it gets to " STA Background " it simply does nothing.
Your "background" variable is located somewhere between 8000-FFFF. Basically nothing happens when you write there, unless it's a mapper register. You can't overwrite PRG.