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+Way Scroll by Malcolm Bamber
+[[http://www.dark-well.pwp.blueyonder.co.uk/]]
+How I scrolled a 2 by 2 tiled map
+I hope it is a help to some one trying to scroll the screen
+This first part here will show you what the irq is doing when called
+__SCROLL UP__
+IF YSCROLL=3
+    ADD ONE TO UDFLAG
+    IF UDFLAG NOT 1 OR 2 THEN THEN QUIT OUT OF IRQ
+    IF UDFLAG=1 THEN SO MOVE MAP POINTER UP ONE LINE IF WE CAN
+    IF UDFLAG=2 THEN COPY SCREEN DOWN ONE LINE
+    SET $D011 TO 3
+    SET YSCROLL TO 5 FOR NEXT TIME IRQ IS CALLED
+IF YSCROLL=5
+    SET $D011 TO 5
+    SET YSCROLL TO 7 FOR NEXT TIME IRQ IS CALLED
+    DRAW TILE AT THE TOP OF THE SCREEN
+    IF UDFLAG=1 THEN DRAW BOTTOM PART OF TILE
+    IF UDFLAG=2	THEN DRAW TOP PART OF TILE
+IF YSCROLL=7
+    SET $D011 TO 7
+    SET YSCROLL TO 1 FOR NEXT TIME IRQ IS CALLED
+    WE SCROLL EACH WAY TWO TIMES
+    IF UDFLAG=1 THEN COPY EVEN COLOURS LINES TO SCREEN COLOUR MAP FROM SPARE COLOUR MAP
+    AND SWAP SCREEN
+    IF UDFLAG=1 THEN COPY ODD COLOURS LINES TO SCREEN COLOUR MAP FROM SPARE COLOUR MAP
+    AND SWAP SCREEN
+IF YSCROLL=1
+    SET YSCROLL TO 3 FOR NEXT TIME IRQ IS CALLED
+__SCROLL DOWN__
+IF YSCROLL=4
+    ADD ONE TO UDFLAG
+    IF UDFLAG NOT 1 OR 2 THEN QUIT OUT OF IRQ
+    IF UDFLAG=1 THEN COPY SCREEN AND COLOUR UP ONE LINE
+    IF UDFLAG=2 THEN SO MOVE MAP POINTER DOWN ONE LINE IF WE CAN
+    SET $D011 TO 4
+    SET YSCROLL TO 2 FOR NEXT TIME IRQ IS CALLED
+IF YSCROLL=2
+    IF UDFLAG=1 THEN DRAW TOP PART OF TILE AT BOTTOM OF SCREEN
+    IF UDFLAG=2 THEN DRAW BOTTOM PART OF TILE AT BOTTOM OF SCREEN
+    SET $D011 TO 2
+    SET YSCROLL TO 0 FOR NEXT TIME IRQ IS CALLED
+IF YSCROLL=0
+    SET $D011 TO 0
+    SET YSCROLL TO 6 NEXT TIME IRQ IS CALLED
+    IF UDFLAG=1 THEN COPY COLOUR ODD LINE TO SCREEN COLOUR MAP AND SWAP SCREEN
+    IF UDFLAG=2 THEN COPE COLOUR EVEN LINE TO SCREEN COLOUR MAP AND SWAP SCREEN
+IF YSCROLL=6
+   SET YSCROLL TO 4 FOR NEXT TIME IRQ IS CALLED
+__SCROLL LEFT__
+IF xscroll=3
+    ADD ONE TO LRFLAG
+    SET XSCROLL TO 5 FOR NEXT TIME IRQ IS CALLED
+    SET $D016 TO 3 FOR SMOOTH SCROLL DOT POSITION
+    IF LRFLAG NOT 1 OR 2 THEN THEN QUIT OUT OF IRQ
+    IF LRFLAG=1 THEN SO MOVE MAP POINTER LEFT ONE POSITION IF WE CAN
+    IF LRFLAG=2 THEN COPY SCREEN RIGHT ONE POSITION
+IF xscroll=5
+    SET XSCROLL TO 7 FOR NEXT TIME IRQ IS CALLED
+    SET $D016 TO 5 FOR SMOOTH SCROLL DOT POSITION
+    DRAW A SIDE OF THE TILE ON THE LEFT SIDE OF THE SCREEN
+IF xscroll=7
+    SET XSCROLL TO 1 FOR NEXT TIME IRQ IS CALLED
+    SET $D016 TO 7 FOR SMOOTH SCROLL DOT POSITION
+    IF LRFLAG=1 THEN COPY COLOUR EVEN POSIION TO SCREEN COLOUR MAP AND SWAP SCREEN
+    IF LRFLAG=2 THEN COPY COLOUR ODD POSITION TO SCREEN COLOUR MAP AND SWAP SCREEN
+IF xscroll=1
+    SET XSCROLL TO 3 FOR NEXT TIME IRQ IS CALLED
+__SCROLL RIGHT__
+IF xscroll=4
+    ADD ONE TO LRFLAG
+    IF LRFLAG NOT 1 OR 2 THEN QUIT OUT IRQ
+    IF LRFLAG=1 THEN SO MOVE MAP POINTER RIGHT ONE POSITION IF WE CAN
+    IF LRFLAG=2 THEN COPY SCREEN LEFT ONE POSITION
+    SET XSCROLL TO 0 FOR NEXT TIME IRQ IS CALLED
+    SET $D016 TO 0 FOR SMOOTH SCROLL DOT POSITION
+IF xscroll=2
+    DRAW LEFT OR RIGHT SIDE OF TILE TO RIGHT SIDE OF SCREEN
+    SET XSCROLL TO 0 FOR NEXT TIME IRQ IS CALLED
+    SET $D016 TO 2 FOR SMOOTH SCROLL DOT POSITION
+IF xscroll=0
+    SET XSCROLL TO 6 FOR NEXT TIME IRQ IS CALLED
+    SET $D016 TO 0 FOR SMOOTH SCROLL DOT POSITION
+    IF LRFLAG=1 THEN COPY COLOUR ODD POSIION TO SCREEN COLOUR MAP AND SWAP SCREEN
+    IF LRFLAG=2 THEN COPY COLOUR EVEN POSIION TO SCREEN COLOUR MAP AND SWAP SCREEN
+IF xscroll=6
+    SET XSCROLL TO 4 FOR NEXT TIME IRQ IS CALLED
+See Part 1 & 2 For Source Code
+Part1 and Part2 Needs To Be Run Together