diff --git a/source/cpu.s b/source/cpu.s
index 21e2942..a69f347 100644
--- a/source/cpu.s
+++ b/source/cpu.s
@@ -135,11 +135,18 @@ cycles  .req r5
     ldrsb r0, [reg_pc], #1
 #ifdef CHECK_IDLE_JUMP
     cmp r0, #-2
-    bne 1f
-    b _xx
+    bne 2f
+    ldr r0, =idle_loop_msg
+    unbase_pc reg_pc
+    mov r1, reg_pc
+    bl iprintf
+1:  b 1b
 #endif
-    // XXX two cycle penality for page crossing
-1:  add reg_pc, r0
+2:  add r1, reg_pc, r0
+    eor r0, r1, reg_pc
+    tst r0, #0x100
+    addne cycles, #2
+    mov reg_pc, r1
 .endm
 
 #define FLAG_CARRY  0x01<<24
@@ -164,18 +171,19 @@ cycles  .req r5
     // Decimal mode
     tst reg_f, #FLAG_DEC
     beq 1f
-    bic reg_f, #FLAG_CARRY
     // Low nibble
-    and r2, reg_a, #0x0f
-    cmp r2, #0x09
+    bic reg_f, #FLAG_CARRY
+    and r1, reg_a, #0x0f
+    cmp r1, #0x09
     addhi reg_a, #0x06
     // High nibble
-    and r1, reg_a, #0xf0<<24
+    and r1, reg_a, #0xf0
     cmp r1, #0x90
     addhi reg_a, #0x60
     orrhi reg_f, #FLAG_CARRY
+    and reg_a, #255
     add cycles, #1
-1:  nop
+1:  
 .endm
 
 .macro op_sbc r
@@ -192,6 +200,7 @@ cycles  .req r5
     tst reg_f, #FLAG_DEC
     beq 1f
     sub reg_a, #0x66
+    and reg_a, #255
     bic reg_f, #FLAG_CARRY
     // Low nibble
     and r2, reg_a, #0x0f
@@ -203,7 +212,7 @@ cycles  .req r5
     addhi reg_a, #0x60
     orrhi reg_f, #FLAG_CARRY
     add cycles, #1
-1:  nop
+1:  
 .endm
 
 .macro op_and a1
@@ -1753,6 +1762,8 @@ unhandled_msg:
 debug_msg:
     .ascii "A%02x X%02x Y%02x OP%02x F%02x SP%02x P%04x\n"
     .byte 0
+#ifdef CHECK_IDLE_JUMP
 idle_loop_msg:
     .ascii "Idle %04x\n"
     .byte 0
+#endif
diff --git a/source/disk.c b/source/disk.c
index 93d2494..6a55da6 100644
--- a/source/disk.c
+++ b/source/disk.c
@@ -66,7 +66,7 @@ u8 disk_io_read (u16 addr)
                         phase = 0;
                     if (phase > 70)
                         phase = 70;
-                    /*track_pos = 0;*/
+                    track_pos = 0;
                     track_start = (phase >> 1) * 6656;
                 }
             }
@@ -80,6 +80,7 @@ u8 disk_io_read (u16 addr)
         case 0x8:
         case 0x9:
             motor_on = set;
+            emu_boost = set;
             return 0xff;
         // SELECT
         case 0xa:
diff --git a/source/emu.c b/source/emu.c
index 3524f1c..143a596 100644
--- a/source/emu.c
+++ b/source/emu.c
@@ -47,6 +47,7 @@ void emu_init ()
     // Set some sane defaults
     emu_vsync = 1;
     emu_hires = 2;
+    emu_boost = 0;
 
     // Setup the video hardware
     video_init();
@@ -66,6 +67,8 @@ void emu_init ()
 
     // Load the disk rom in place
     load_buf(disk_rom, 0xc600, 0x100);
+
+    /*mainram[0xFCA8] = 0x60;*/
 #else
     if (load_bin("6502_functional_test.bin", 0x0, -1, NULL) > 0) {
         const u16 reset_patch = 0x0400;
@@ -104,7 +107,7 @@ void emu_run ()
 
         sound_play();
 
-        if (emu_vsync)
+        if (emu_vsync && !emu_boost)
             swiWaitForVBlank();
         bgUpdate();
     }
diff --git a/source/emu.h b/source/emu.h
index 0c2d461..a715778 100644
--- a/source/emu.h
+++ b/source/emu.h
@@ -12,6 +12,7 @@
 #define INPUT_KEYBOARD 1
 
 int emu_vsync;
+int emu_boost;
 int emu_input;
 int emu_screen;
 int emu_scale;
diff --git a/source/main.c b/source/main.c
index 9d0c8a0..81d4b18 100644
--- a/source/main.c
+++ b/source/main.c
@@ -30,7 +30,7 @@ int main(int argc, char **argv)
         /*load_disk("Airheart (1986)(Broderbund)[cr].dsk");*/
         // Slow loading
         /*load_disk("PACMAN.DSK");*/
-        /*load_disk("Karateka (1984)(Broderbund).dsk");*/
+        load_disk("Karateka (1984)(Broderbund).dsk");
         // Awesome!
         /*load_disk("lode.dsk");*/
         // AppleII+
diff --git a/source/mem.s b/source/mem.s
index 6899568..f44f74e 100644
--- a/source/mem.s
+++ b/source/mem.s
@@ -207,7 +207,7 @@ mem_reset:
 .ltorg
 
 .bss
-.align 4
+.p2align 8
 mainram:
     .space 0x10000
 lcram:
diff --git a/source/menu.c b/source/menu.c
index 2531f4c..6645e6b 100644
--- a/source/menu.c
+++ b/source/menu.c
@@ -112,12 +112,12 @@ void menu_print_page (const page_t *page)
                 sel_entry->cb(*sel_entry->opt_ptr);
         }
 
-        if (keys&KEY_A && sel_entry->confirm && sel_entry->cb) {
+        if (keys&KEY_A && sel_entry->cb) {
             sel_entry->cb(*sel_entry->opt_ptr);
             return;
         }
 
-        if (keys&KEY_B)
+        if (keys&(KEY_B|KEY_START))
             return;
 
         swiWaitForVBlank();