diff --git a/gb.c b/gb.c
index 2e7c69c..7770552 100644
--- a/gb.c
+++ b/gb.c
@@ -6,12 +6,10 @@
 #include <fcntl.h>
 
 int savereq, loadreq;
-int cpuhalt;
-int backup;
 int savefd = -1;
 int saveframes;
 const char *romname;
-u8 mbc, feat, mode;
+u8 mbc, mode;
 
 void
 writeback(void)
@@ -68,6 +66,7 @@ loadsave(const char *file)
 static void
 loadrom(const char* file)
 {
+	int feat;
   FILE* f;
   long sz;
   static u8 mbctab[31] = { 0, 1, 1, 1, -1, 2, 2, -1, 0,  0, -1, 6, 6, 6, -1, 3,
@@ -114,8 +113,8 @@ loadrom(const char* file)
       break;
     default: panic("unsupported mbc %d", mbc);
   }
-  if ((rom[0x143] & 0x80) != 0 && (mode & FORCEDMG) == 0)
-    mode = CGB | COL;
+  if (rom[0x143] & 0x80 != 0)
+		panic("unsupported color");
 	if((feat & FEATBAT) != 0)
 		loadsave(file);
 }
@@ -147,11 +146,7 @@ flush()
 static void
 colinit(void)
 {
-  union
-  {
-    u8 c[4];
-    u32 l;
-  } c;
+  union {u8 c[4]; u32 l;}c;
 
   c.c[3] = 0;
   for (int i = 0; i < 4; i++) {
diff --git a/gb.h b/gb.h
index d9735e0..973b9be 100644
--- a/gb.h
+++ b/gb.h
@@ -174,15 +174,14 @@ extern u32 pal[64];
 extern u8 dma;
 extern u32 divclock;
 extern u64 clock;
-extern u8 ppuy, ppustate, ppuw;
+extern u8 ppuy, ppustate;
 extern u8 keys;
 extern int prish;
 extern u8 mode;
-extern u8 mbc, feat;
+extern u8 mbc;
 extern Event* elist;
 extern Event evhblank, evjoypad;
 extern u32 moncols[4];
-extern u32 white;
 extern u8* pic;
 extern int (*mapper)(int, int);
 extern Event *events[NEVENT];
diff --git a/mem.c b/mem.c
index a483482..c7038fa 100644
--- a/mem.c
+++ b/mem.c
@@ -71,7 +71,6 @@ regwrite(u16 a, u8 v)
       ppusync();
       if ((~v & reg[a] & LCDEN) != 0) {
         ppuy = 0;
-        ppuw = 0;
         ppustate = 0;
         delevent(&evhblank);
       }
@@ -236,13 +235,9 @@ mbc1(int a, int v)
 }
 
 void
-meminit(void)
+meminit()
 {
-  union
-  {
-    u8 c[4];
-    u32 l;
-  } c;
+  union {u8 c[4]; u32 l;}c;
 
   c.c[0] = c.c[1] = c.c[2] = 0;
   c.c[3] = 1;
@@ -250,14 +245,12 @@ meminit(void)
     c.l >>= 1;
   c.c[0] = c.c[1] = c.c[2] = 0xff;
   c.c[3] = 0;
-  white = c.l;
 
   romb = rom + 0x4000;
   wramb = wram + 0x1000;
   vramb = vram;
   mapper = mappers[mbc];
   mapper(INIT, 0);
-
   reg[LCDC] = 0x91;
   reg[IF] = 0xE0;
   reg[SVBK] = 0xff;
diff --git a/ppu.c b/ppu.c
index 6790111..43dc764 100644
--- a/ppu.c
+++ b/ppu.c
@@ -34,7 +34,7 @@ enum
 };
 
 jmp_buf mainjmp,renderjmp;
-u8 ppustate, ppuy, ppuw;
+u8 ppustate, ppuy;
 u64 hblclock, rendclock;
 static int cyc, ppux, ppux0;
 sprite spr[10], *sprm;
@@ -110,8 +110,8 @@ ppurender(void)
     } while (m > 8);
     if (win == -1) {
       win = 1;
-      ta = 0x1800 | reg[LCDC] << 4 & 0x400 | ppuw - reg[WY] << 2 & 0x3E0;
-      y = ppuw - reg[WY] << 1 & 14;
+      ta = 0x1800 | reg[LCDC] << 4 & 0x400 | ppuy - reg[WY] << 2 & 0x3E0;
+      y = ppuy - reg[WY] << 1 & 14;
       cyc += 12;
       m = 175 - reg[WX];
       goto restart;
@@ -193,11 +193,11 @@ sprites(void)
     for (; x < x1; ++x) {
       attr = picp[x] >> prish;
       chr = q->chr;
-      if ((chr & ((q->t & SPRXFL) != 0 ? 0x0101 : 0x8080)) != 0 &&
+      if((chr & ((q->t & SPRXFL) != 0 ? 0x0101 : 0x8080)) != 0 &&
           (attr & TILSPR) == 0 &&
           ((mode & COL) != 0 && (reg[LCDC] & BGPRI) == 0 ||
            (attr & TILCOL0) != 0 ||
-           (attr & TILPRI) == 0 && (q->t & SPRPRI) == 0)) {
+           (attr & TILPRI) == 0 && (q->t & SPRPRI) == 0)){
         if ((q->t & SPRXFL) == 0)
           picp[x] = pal[q->pal | chr >> 15 | chr >> 6 & 2] | TILSPR << prish;
         else
@@ -245,8 +245,6 @@ hblanktick(void* _)
   switch (ppustate) {
   case 0:
     hblclock = clock + evhblank.time;
-    if (reg[WX] <= 166 && reg[WY] <= 143)
-      ppuw++;
     if (++ppuy == 144) {
       ppustate = 1;
       if (reg[STAT] & IRQM1)
@@ -265,11 +263,8 @@ hblanktick(void* _)
     break;
   case 1:
     hblclock = clock + evhblank.time;
-    if (reg[WX] <= 166 && reg[WY] <= 143)
-      ppuw++;
     if (++ppuy == 154) {
       ppuy = 0;
-      ppuw = 0;
       ppustate = 2;
       if (reg[STAT] & IRQM2)
         reg[IF] |= IRQLCDS;