scrolling code

REP #$20	;Make A 16 bits wide
LDA $1462		;Load the layer 1 x position
LSR		;Divide by 2.  The more times you use LSR the slower the background will scroll horizontally.
LSR		;If you use ASL (multiply by 2) instead the background will scroll <i>faster</i> than the foreground.
STA $22		;Store to the layer 3 x position

LDA $1464		;Load the layer 1 y position
LSR		;Same as above, but vertically.
LSR
SEC		;These two lines are for shifting your background vertically.
SBC #$0038	;If you're using a background that loops you probably won't have to use this.
STA $24		;Store to the layer 3 y position
SEP #$20	;Make A 8 bits wide