This is a code snippet of how a 2×2 sideways scrolling message works. Like with the 1×1 scrolling message routine, it reads a $D016 control pointer XPos, and shifts it 7 pixels before shifting the character columns on both rows of the screen. The scroll then reads the positions of Scrolltext. If @ is found, the message resets otherwise, the code will check whether or not the pointer “Case” is using upper or lower char then stores it to the very last column. The message in the Scrolltext location will not be updated until after the upper case has been read.

// Simple Scrolling message test routine 
    
Scroller:
		lda XPos 
		sec 
		sbc #2
		and #$07
		sta XPos 
		bcs ExitScroll
		jmp MainScroll 
ExitScroll:
		rts 
MainScroll:
		ldx #$00
ShiftByte:
		lda $0400+(15*40)+1,x 
		sta $0400+(15*40),x 
		inx 
		cpx #$50
		bne ShiftByte 
MessRead:
		lda Scrolltext
		cmp #$00
		bne UpdateMess
		lda #<Scrolltext 
		sta MessRead+1
		lda #>Scrolltext 
		sta MessRead+2
		jmp MessRead 
UpdateMess:
		sta CharStore
		lda Case 
		cmp #1
		beq UpperCase 
LowerCase:
		lda CharStore
		sta $0400+(15*40)+39
		eor #$80
		sta $0400+(16*40)+39
		lda #1
		sta Case 
		rts 
UpperCase: 
		lda CharStore
		eor #$40
		sta $0400+(15*40)+39
		eor #$80
		sta $0400+(16*40)+39 
		lda #0
		sty Case 
		inc MessRead+1
		bne ExitScroll2
		inc MessRead+2 
ExitScroll2:
		rts

Case: .byte 0 // Which char code are we using (upper or lower)
XPos: .byte 0 // $D016 control pointer


Scrolltext: .text " ... this is a 2x2 character scrolling message ... "
            .text "or it can be very short ...   i'll leave it up to you ...   "