diff --git a/.vscode/launch.json b/.vscode/launch.json
index 0e1c476..81045b8 100644
--- a/.vscode/launch.json
+++ b/.vscode/launch.json
@@ -4,19 +4,6 @@
     // Weitere Informationen finden Sie unter https://go.microsoft.com/fwlink/?linkid=830387
     "version": "0.2.0",
     "configurations": [
-    
-
-
-
-
-
-
-    
-    
-
-
-
-
         {
             "type": "cc65-vice",
             "request": "launch",
diff --git a/SConstruct b/SConstruct
index 739c68d..31b1429 100644
--- a/SConstruct
+++ b/SConstruct
@@ -26,7 +26,7 @@ env = Environment(
         'DISPLAY': display,
     },
     AS = 'ca65',
-    ASFLAGS = ['-t', 'c64', '-g'],
+    ASFLAGS = ['-t', 'c64', '-g', '--cpu', '6502x'],
     CC = 'cl65',
     CFLAGS = ['-DSCREEN_START=0x'+screen_start, '-DSPRITE_START=0x'+sprite_start, '-DCHARACTER_START=0x'+character_start, '-O', '-Osir', '-t', 'c64', '-C', 'c64.cfg', '-g', '-Wc', '--debug-tables', '-Wc', '${SOURCE}.tab'],
     LINK = 'cl65',
diff --git a/src/main.c b/src/main.c
index 4e9bdf8..86beb3e 100644
--- a/src/main.c
+++ b/src/main.c
@@ -236,8 +236,10 @@ void set_sprite_x(sprite_handle a, unsigned int x) {
 }
 
 void set_sprite_y(sprite_handle a, unsigned char y) {
-    static sprite_handle *start_handle, *comp_handle, *current_handle;
-    static sprite_handle arg, comp;
+    register sprite_handle *comp_handle, *current_handle;
+    register sprite_handle comp;
+    static sprite_handle* start_handle;
+    static sprite_handle arg;
     static unsigned char index, last_index, hi_mask, comp_y, yarg;
     static bool direction, is_last;
 
@@ -298,17 +300,13 @@ void set_sprite_y(sprite_handle a, unsigned char y) {
 
         hi_mask = 1<<(index%VIC_SPR_COUNT);
 
-        __asm__("lda %v", comp);
-        __asm__("ldx %v+1", comp);
         __asm__("ldy #%b", offsetof(struct sprite_data, ena));
-        __asm__("sta ptr1");
-        __asm__("stx ptr1+1");
 
         __asm__("ldx %v", hi_mask);
-        __asm__("loop: lda (ptr1),Y");
+        __asm__("loop: lda (%v),Y", comp);
         __asm__("beq done");
         __asm__("txa");
-        __asm__("sta (ptr1),Y");
+        __asm__("sta (%v),Y", comp);
         __asm__("done: iny");
         __asm__("tya");
         __asm__("sbc #%b", offsetof(struct sprite_data, multi));
@@ -383,13 +381,11 @@ struct waw {
 };
 typedef struct waw waw;
 
-void init_waw(waw* w) {
+void init_waw(register waw* waw) {
     static unsigned int x, sprite_x;
     static unsigned char i, j, y, sprite_y, idx;
-    static waw* waw;
     static sprite_handle sprite;
     static sprite_handle* sprites;
-    waw = w;
 
     x = waw->x + SCREEN_SPRITE_BORDER_X_START;
     y = waw->y + SCREEN_SPRITE_BORDER_Y_START;
@@ -418,14 +414,12 @@ void init_waw(waw* w) {
     }
 }
 
-void update_waw(waw* w) {
+void update_waw(register waw* waw) {
     static unsigned char y;
     static unsigned char idx;
     static signed char change_y, mouth_offset;
     static sprite_handle* sprites;
     static sprite_handle sprite;
-    static waw* waw;
-    waw = w;
     mouth_offset = waw->mouth_offset;
     if(waw->mouth_direction) {
         mouth_offset+=WAW_MOUTHSPEED;
diff --git a/src/main_raster_irq_asm.s b/src/main_raster_irq_asm.s
index 1bbde38..01316af 100644
--- a/src/main_raster_irq_asm.s
+++ b/src/main_raster_irq_asm.s
@@ -24,12 +24,10 @@
     tax
 
     ldy __sprite_list,X
-    sty current_sprite
     sty ptr1
 
     inx
     ldy __sprite_list,X
-    sty current_sprite+1
     sty ptr1+1
 
     ldy #$03 ; FIXME offsetof(lo_y)
@@ -52,23 +50,11 @@ vic_sprite:     .byte $00
 current_y:      .byte $00
 new_y:          .byte $00
 hi_mask:        .byte $00
-current_sprite: .res 2
 raster_clock:   .byte $06
 
 .segment "CODE"
 
 .proc main_raster_irq
-    ; Make sure this is a raster interrupt and we're ready
-    lda _irq_setup_done
-    jeq unhandled
-    lda VIC_IRQ_RASTER
-    bit VIC_IRR
-    jeq unhandled
-
-    ; set the flag so we know we've handled it
-    ora VIC_IRR
-    sta VIC_IRR
-
     ; if we're at the beginning of the sprite loop, initialize the variables
     lda sprite_index
     cmp #$ff
@@ -102,22 +88,7 @@ sprite_update_loop:
     lda new_y
     sta current_y
 
-    lda #$01
-    ldx vic_sprite
-    beq done
-shift:
-    asl
-    dex
-    bne shift
-done:
-    eor #$ff
-    sta hi_mask
-
     ; prep the pointer for struct access
-    lda current_sprite
-    ldx current_sprite+1
-    sta ptr1
-    stx ptr1+1
     ldy #$00 ; FIXME offsetof(color)
 
     ; store color and pointer into arrays
@@ -156,7 +127,11 @@ write_vic_sprite:
     inx
     stx VIC_HLINE
 
+    ; Use enable bit as mask
     iny
+    lda (ptr1),Y
+    eor #$ff
+    sta hi_mask
     himasker VIC_SPR_ENA
 
     iny
@@ -205,6 +180,17 @@ unhandled:
 .endproc
 
 .proc raster_irq
+    ; Make sure this is a raster interrupt and we're ready
+    lda _irq_setup_done
+    beq unhandled
+    lda VIC_IRQ_RASTER
+    bit VIC_IRR
+    beq unhandled
+
+    ; set the flag so we know we've handled it
+    ora VIC_IRR
+    sta VIC_IRR
+
     lda ptr1
     ldx ptr1+1
     sta ptr1_save
@@ -220,4 +206,8 @@ unhandled:
     sta ptr1
     stx ptr1+1
     rts
+unhandled:
+    lda IRQ_NOT_HANDLED
+    lsr
+    rts
 .endproc
\ No newline at end of file