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+====== Moving sprites / Sorting movement from VIC update ======
+by Achim
+===== x+msb =====
+Moving sprites can be annoying in terms of msb handling. To avoid the msb issue you usually use tables for moving the sprites and let a small routine update the VIC registers every frame.
+<code>
+spritey:	.byte $00, $00, $00, $00, $00, $00, $00, $00
+spritex:	.byte $00, $00, $00, $00, $00, $00, $00, $00
+spritemsb:	.byte $00, $00, $00, $00, $00, $00, $00, $00
+spritecolor: 	...
+spritepointer: 	...
+</code>
+Now simple 16bit additions/subtractions apply to moving sprites. The main program can ignore the msb handling.
+Here's a small routine to update VIC registers. Should be called by an irq. Preferably before VIC starts to draw the next frame.
+<code>
+		ldx #$07
+		ldy #$0e
+loop:		lda srpitey,x
+		sta $d001,y		//write y
+		lda spritex,x
+		sta $d000,y		//write x
+		lda spritemsb,x
+		cmp #$01		//no msb=carry clear  / msb=carry set
+		rol $d010		//carry -> $d010, repeat 8 times and all bits are set
+		lda spritecolor,x
+		sta $d027,x
+		lda spritepointer,x
+		sta $07f8,x		//screen at $0400
+		dey
+		dey
+		dex
+		bpl loop
+</code>
+===== Oldschool: x*2 =====
+This allows to use 8bit calculations for moving the sprite on x axis. No need for a msb table anymore. On the downside sprites can only be moved with 2px/frame.
+<code>
+spritey:	.byte $00, $00, $00, $00, $00, $00, $00, $00
+spritex:	.byte $00, $00, $00, $00, $00, $00, $00, $00
+spritecolor: 	...
+spritepointer: 	...
+</code>
+Update VIC registers:
+<code>
+	ldx #$07
+	ldy #$0e
+loop:	lda srpitey,x
+	sta $d001,y		//write y
+	lda spritex,x
+	asl			//x*2>$ff -> carry set=msb, x*2<=$ff -> carry clear=no msb
+	sta $d000,y		//write x*2
+	rol $d010		//carry -> $d010
+	lda spritecolor,x
+	sta $d027,x
+	lda spritepointer,x
+	sta $07f8,x		//screen at $0400
+        dey
+	dey
+	dex
+	bpl loop
+</code>