diff --git a/bun.c b/bun.c
index 8923995..f4b593d 100644
--- a/bun.c
+++ b/bun.c
@@ -26,7 +26,6 @@
 
 #define BUN_MAX_RANGE (31 + 320)
 
-#define BUN_COUNT (12)
 #define BUN_SPEED (1)
 
 #define BUN_HORIZ_DISTANCE_BETWEEN_BUNS ((BUN_MAX_RANGE / 4) - COOL_BUN_WIDTH)
@@ -48,12 +47,6 @@ extern unsigned char chip coolbun[];
 
 extern struct Custom far custom;
 
-void setupBun(void) {
-}
-
-void teardownBun(void) {
-}
-
 #define BLITTER_ASCENDING (0)
 #define BLITTER_DESCENDING (1)
 
@@ -310,13 +303,6 @@ void calculateBunPositions(
 
     bunPositions[current][0] = x;
     bunPositions[current][1] = y;
-
-    // for the blitter video
-    /*
-    if (frame == 0) {
-      printf("%d,%d\n", bunPositions[current][0], bunPositions[current][1]);
-    }
-    */
   }
 }
 
@@ -366,12 +352,15 @@ void setupBunRenderer(
   bunRenderer->screenDefinition = screenDefinition;
   bunRenderer->activeScreenBufferDetails = activeScreenBufferDetails;
 
-  setupBun();
   buildBunAngleAdjustments();
   calculateAllBunPositions(screenDefinition);
   precalculateBunRenderInfo();
 }
 
+/**
+ * Is there bun clear information for this frame? This is not true for the
+ * first frame in the demo.
+ */
 int hasBunClear[2] = {0,0};
 struct BunClear bunClearForScreen[2][BUN_COUNT];
 
@@ -430,6 +419,42 @@ void renderBunFrame(
   hasBunClear[bunRenderer->activeScreenBufferDetails->currentBuffer] = 1;
 }
 
-void teardownBunRenderer() {
-  teardownBun();
+void calculateNeededRedrawRanges(
+  int frame,
+  uint16_t redrawRanges[BUN_COUNT][4]
+) {
+  int i, sx, sy, ex, ey, tmp;
+
+  int thisFrame = frame % FRAMES_FOR_SCREEN;
+  int lastFrame = (frame + FRAMES_FOR_SCREEN - 1) % FRAMES_FOR_SCREEN;
+
+  for (i = 0; i < BUN_COUNT; ++i) {
+    sx = allBunPositionsByFrame[lastFrame][i][0];
+    if (
+      allBunPositionsByFrame[lastFrame][i][1] <
+      allBunPositionsByFrame[thisFrame][i][1]
+    ) {
+      sy = allBunPositionsByFrame[lastFrame][i][1];
+      ey = allBunPositionsByFrame[thisFrame][i][1] + COOL_BUN_HEIGHT;
+    } else {
+      sy = allBunPositionsByFrame[thisFrame][i][1];
+      ey = allBunPositionsByFrame[lastFrame][i][1] + COOL_BUN_HEIGHT;
+    }
+
+    ex = allBunPositionsByFrame[thisFrame][i][0] + COOL_BUN_WIDTH;
+
+    if (sx > ex) {
+      tmp = sx;
+      sx = ex;
+      ex = tmp;
+    }
+
+    redrawRanges[i][0] = sx;
+    redrawRanges[i][1] = sy;
+    redrawRanges[i][2] = ex;
+    redrawRanges[i][3] = ey;
+  }
+}
+
+void teardownBunRenderer() {
 }
diff --git a/bun.h b/bun.h
index d22fe2d..90db276 100644
--- a/bun.h
+++ b/bun.h
@@ -4,6 +4,7 @@
 #include "screen.h"
 
 #define FRAMES_FOR_SCREEN (60)
+#define BUN_COUNT (12)
 
 struct BunRenderer {
   struct ScreenDefinition *screenDefinition;
@@ -24,4 +25,9 @@ void clearCurrentBuns(
   struct BunRenderer *
 );
 void teardownBunRenderer(void);
+
+void calculateNeededRedrawRanges(
+  int frame,
+  uint16_t redrawRanges[BUN_COUNT][4]
+);
 #endif
diff --git a/main.c b/main.c
index 2ee1bbf..1759cea 100644
--- a/main.c
+++ b/main.c
@@ -172,10 +172,104 @@ void buildCopperlist(void) {
   endCopperlist(currentCopperlist);
 }
 
+void renderTopazPartials(
+  uint16_t redrawRanges[BUN_COUNT][4]
+) {
+  int plane, i, topazX;
+
+  uint16_t bltcon0;
+  uint16_t bltamod, bltbmod, bltcmod, bltdmod;
+  uint16_t width, height, bltsize;
+  uint8_t *bltapt, *bltbpt, *bltcpt, *bltdpt;
+
+  bltcon0 = 0xca + (1 << 8) + (1 << 9) + (1 << 10) + (1 << 11);
+  bltcmod = screenDefinition.byteWidth;
+  bltbpt = TopazBitplanes;
+
+
+  for (i = 0; i < BUN_COUNT; ++i) {
+    if (redrawRanges[i][2] - redrawRanges[i][0] < TOPAZ_WIDTH_PIXELS) {
+      if (
+        (redrawRanges[i][2] > 64 && redrawRanges[i][0] < (64 + TOPAZ_WIDTH_PIXELS)) ||
+        (redrawRanges[i][0] < (64 + TOPAZ_WIDTH_PIXELS) && redrawRanges[i][2] > 64)
+      ) {
+        width = redrawRanges[i][2] - redrawRanges[i][0];
+        height = redrawRanges[i][3] - redrawRanges[i][1];
+        topazX = redrawRanges[i][0] - 64;
+
+        if (topazX < 0) {
+          topazX += 16;
+          width -= 16;
+        }
+        // always round up to the next word
+        width += 16;
+
+        bltapt = redrawRanges[i][1] * TOPAZ_WIDTH_BYTES + (topazX >> 4) * 2;
+        bltbpt = bltapt;
+        bltcpt = redrawRanges[i][1] * screenDefinition.byteWidth + (redrawRanges[i][0] >> 4) * 2;
+        bltdpt = bltcpt;
+
+        bltamod = TOPAZ_WIDTH_BYTES - (width >> 4) * 2;
+        bltbmod = bltamod;
+        bltcmod = screenDefinition.byteWidth - (width >> 4) * 2;
+        bltdmod = bltcmod;
+
+        bltsize = BLTSIZE((width >> 4), height);
+
+        printf(
+          "Coords: %d, %d -> %d, %d\n",
+          redrawRanges[i][0],
+          redrawRanges[i][1],
+          redrawRanges[i][2],
+          redrawRanges[i][3]
+        );
+
+        printf("topazX: %d\n", topazX);
+        printf("width: %d\n", width);
+
+        printf("BLTAPT: %d\n", bltapt);
+        printf("BLTBPT: %d\n", bltbpt);
+        printf("BLTCPT: %d\n", bltcpt);
+        printf("BLTDPT: %d\n", bltdpt);
+
+        printf("BLTAMOD: %d\n", bltamod);
+        printf("BLTBMOD: %d\n", bltbmod);
+        printf("BLTCMOD: %d\n", bltcmod);
+        printf("BLTDMOD: %d\n", bltdmod);
+
+        printf("BLTSIZE: %d, %d\n", (width >> 4), height);
+
+        /*
+        for (plane = 0; plane < 3; ++plane) {
+          custom.bltcon0 = bltcon0;
+          custom.bltcon1 = 0;
+          custom.bltafwm = 0xffff;
+          custom.bltalwm = 0xffff;
+          custom.bltapt = MaskBitplane;
+          custom.bltbpt = bltbpt;
+          custom.bltcpt = activeScreenBufferDetails.planes[plane] + 8;
+          custom.bltdpt = activeScreenBufferDetails.planes[plane] + 8;
+          custom.bltamod = 0;
+          custom.bltbmod = 0;
+          custom.bltcmod = bltcmod;
+          custom.bltdmod = bltcmod;
+          custom.bltsize = BLTSIZE(TOPAZ_WIDTH_WORDS, 256);
+
+          bltbpt += TOPAZ_WIDTH_BYTES * 256;
+
+          WaitBlit();
+        }
+        */
+      }
+    }
+  }
+}
+
 int main(void) {
   int i;
 
   struct BunRenderer bunRenderer;
+  uint16_t redrawRanges[BUN_COUNT][4];
 
   printf("\nCool bun blitter, copper, and sprite demo by John Bintz\n");
   printf("\n");
@@ -229,21 +323,30 @@ int main(void) {
   }
   */
 
+  calculateNeededRedrawRanges(0, redrawRanges);
+  renderTopazPartials(redrawRanges);
+
+  /*
   takeOverSystem();
 
   setCopperlist(copperlist);
   setUpDisplay((uint32_t)screenDefinition.bitplanes);
 
+  renderTopaz();
+  swapCurrentScreenBuffer(&screenDefinition, &activeScreenBufferDetails);
+  renderTopaz();
+  swapCurrentScreenBuffer(&screenDefinition, &activeScreenBufferDetails);
+
   i = 0;
 
-  while (1) {
+
+  while (0) {
     swapCurrentScreenBuffer(&screenDefinition, &activeScreenBufferDetails);
 
-    clearCurrentBuns(&bunRenderer);
 
+    clearCurrentBuns(&bunRenderer);
     renderBunFrame(i, &bunRenderer);
 
-    renderTopaz();
 
     updateDisplayInCopperList(
       &screenDefinition,
@@ -256,10 +359,11 @@ int main(void) {
     if ((ciaa.ciapra >> 6) != 3) break;
 
     i++;
-    i %= FRAMES_FOR_SCREEN;
+    //i %= FRAMES_FOR_SCREEN;
   }
 
   giveBackSystem();
+  */
 
   teardownScreen(&screenDefinition);
 
diff --git a/system/system.h b/system/system.h
index fd66a68..346ae8e 100644
--- a/system/system.h
+++ b/system/system.h
@@ -12,6 +12,11 @@
 // copperlist
 extern void initializeCopperlist(void *copperlist);
 extern uint16_t* endCopperlist(uint16_t *copperlist);
+/**
+  * This only adds bitplane pointers to the copperlist
+  * and sets it up for double buffering.
+  * You still need to configure the playfield hardware.
+  */
 extern uint16_t* addDisplayToCopperlist(
   uint16_t *copperlist,
   struct ScreenDefinition *,
diff --git a/system/system.s b/system/system.s
index 61e30a3..360f676 100644
--- a/system/system.s
+++ b/system/system.s
@@ -73,7 +73,6 @@ ActiveScreenBufferDetails_planes EQU SOFFSET
 SOFFSET SET SOFFSET+(8*4)
   LABEL ActiveScreenBufferDetails_SIZEOF
 
-BPLCON0_COLOR EQU $200
 
 M68K_LEVEL3_INTERRUPT_AUTOVECTOR EQU $6C
 _takeOverSystem:
@@ -268,7 +267,6 @@ _addDisplayToCopperlist:
     LEA ActiveScreenBufferDetails_planes(A3),A3
     ; a3 contains address to planes
 
-
     MOVEQ #0,D0
     MOVE.W ScreenDefinition_bitplanes(A2),D0
     ; d0 is num of bitplanes
@@ -289,9 +287,10 @@ _addDisplayToCopperlist:
     ; get this position for later updating
     MOVE.L A1,(A4)+
     MOVE.W D3,(A1)+
+    ADDQ #2,D1
+
     ; low byte
     SWAP D3
-    ADDQ #2,D1
     MOVE.W D1,(A1)+
     ; get this position for later updating
     MOVE.L A1,(A4)+
@@ -340,34 +339,44 @@ _endCopperlist:
 
   RTS
 
+BPLCON0_ENABLE_COMPOSITE_COLOR EQU $200
+
+; TODO: [ ] Create a stock display structure w/ all the default values in it
+;           that can be overridden, with guides/help on how to do so, then
+;           have this accept that structure
 ; @stack bitplaneCount
 _setUpDisplay:
   MOVE.L D2,-(SP)
-    MOVE.L 8(A7),D2
+    MOVE.L 8(A7),D2 ; bitplaneCount
 
     LEA _custom,A1
 
     MOVEQ #0,D0
-    MOVE.W #BPLCON0_COLOR,D0
+    MOVE.W #BPLCON0_ENABLE_COMPOSITE_COLOR,D0
 
+    ; move bitplane count to bits 12-14
     MOVEQ #0,D1
     MOVE.W D2,D1
-
     AND.W #$7,D1
     ROL.W #8,D1
     ROL.W #4,D1
     ADD.W D1,D0
+
     MOVE.W D0,bplcon0(A1)
 
+    ; this controls horizontal scroll. I'm not good enough
+    ; yet to provide opinions on this.
     MOVE.W #0,bplcon1(A1)
-    ; sprites always on top
+
+    ; sprites always on top for this demo
     MOVE.W #$0020,bplcon2(A1)
+
+    ; no modulos needed
     MOVE.W #0,bpl1mod(A1)
     MOVE.W #0,bpl2mod(A1)
+
+    ; pal default
     MOVE.W #$2c81,diwstrt(A1)
-    ; pal trick
-    ;MOVE.W #$f4c1,diwstop(A1)
-    ;MOVE.W #$38c1,diwstop(A1)
     MOVE.W #$2cc1,diwstop(A1)
     MOVE.W #$0038,ddfstrt(A1)
     MOVE.W #$00d0,ddfstop(A1)