diff --git a/Core/apu.c b/Core/apu.c
index 59970ec2..b79aad96 100755
--- a/Core/apu.c
+++ b/Core/apu.c
@@ -385,7 +385,7 @@ void GB_apu_run(GB_gameboy_t *gb)
     
     if (gb->apu_output.sample_rate) {
         gb->apu_output.cycles_since_render += cycles;
-        double cycles_per_sample = GB_get_clock_rate(gb) / (double)gb->apu_output.sample_rate;
+        double cycles_per_sample = 2 * GB_get_clock_rate(gb) / (double)gb->apu_output.sample_rate; /* 2 * because we use 8MHz units */
         
         if (gb->apu_output.sample_cycles > cycles_per_sample) {
             gb->apu_output.sample_cycles -= cycles_per_sample;
diff --git a/Core/apu.h b/Core/apu.h
index bd69ac4f..fd947f77 100644
--- a/Core/apu.h
+++ b/Core/apu.h
@@ -127,7 +127,7 @@ typedef struct {
     volatile bool copy_in_progress;
     volatile bool lock;
     
-    double sample_cycles;
+    double sample_cycles; // In 8 MHz units
     
     // Samples are NOT normalized to MAX_CH_AMP * 4 at this stage!
     unsigned cycles_since_render;
diff --git a/Core/debugger.c b/Core/debugger.c
index 7fc7b2a9..75178c82 100644
--- a/Core/debugger.c
+++ b/Core/debugger.c
@@ -1411,8 +1411,8 @@ static bool lcd(GB_gameboy_t *gb, char *arguments, char *modifiers, const debugg
     GB_log(gb, "    LYC interrupt: %s\n", (gb->io_registers[GB_IO_STAT] & 64)? "Enabled" : "Disabled");
     
     
-    GB_log(gb, "\nCycles since frame start: %d\n", gb->display_cycles);
-    GB_log(gb, "Current line: %d\n", gb->display_cycles / 456);
+    GB_log(gb, "\nCycles since frame start: %d\n", gb->display_cycles / 2);
+    GB_log(gb, "Current line: %d\n", gb->display_cycles / 456 / 2);
     GB_log(gb, "LY: %d\n", gb->io_registers[GB_IO_LY]);
     GB_log(gb, "LYC: %d\n", gb->io_registers[GB_IO_LYC]);
     GB_log(gb, "Window position: %d, %d\n", (signed) gb->io_registers[GB_IO_WX] - 7 , gb->io_registers[GB_IO_WY]);
diff --git a/Core/display.c b/Core/display.c
index 41f85bf1..a3370b90 100755
--- a/Core/display.c
+++ b/Core/display.c
@@ -15,13 +15,15 @@
  Todo: Mode lengths are not constants, see http://blog.kevtris.org/blogfiles/Nitty%20Gritty%20Gameboy%20VRAM%20Timing.txt
  */
 
-#define MODE2_LENGTH (80)
-#define MODE3_LENGTH (172)
-#define MODE0_LENGTH (204)
+/* The display (logically) runs in 8MHz units, so we double our length constants */
+#define MODE2_LENGTH (80 * 2)
+#define MODE3_LENGTH (172 * 2)
+#define MODE0_LENGTH (204 * 2)
 #define LINE_LENGTH (MODE2_LENGTH + MODE3_LENGTH + MODE0_LENGTH) // = 456
 #define LINES (144)
 #define WIDTH (160)
-#define VIRTUAL_LINES (LCDC_PERIOD / LINE_LENGTH) // = 154
+#define FRAME_LENGTH (LCDC_PERIOD * 2)
+#define VIRTUAL_LINES (FRAME_LENGTH / LINE_LENGTH) // = 154
 
 typedef struct __attribute__((packed)) {
     uint8_t y;
@@ -332,9 +334,9 @@ static void update_display_state(GB_gameboy_t *gb, uint8_t cycles)
         
         /* Keep sending vblanks to user even if the screen is off */
         gb->display_cycles += cycles;
-        if (gb->display_cycles >= LCDC_PERIOD) {
+        if (gb->display_cycles >= FRAME_LENGTH) {
             /* VBlank! */
-            gb->display_cycles -= LCDC_PERIOD;
+            gb->display_cycles -= FRAME_LENGTH;
             display_vblank(gb);
         }
 
@@ -344,23 +346,23 @@ static void update_display_state(GB_gameboy_t *gb, uint8_t cycles)
         return;
     }
     
-    uint8_t atomic_increase = gb->cgb_double_speed? 2 : 4;
+    uint8_t atomic_increase = gb->cgb_double_speed? 4 : 8;
     /* According to AntonioND's docs this value should be 0 in CGB mode, but tests I ran on my CGB seem to contradict
        these findings.
        Todo: Investigate what causes the difference between our findings */
-    uint8_t stat_delay = gb->cgb_double_speed? 2 : 4; // (gb->cgb_mode? 0 : 4);
+    uint8_t stat_delay = gb->cgb_double_speed? 4 : 8; // (gb->cgb_mode? 0 : 8);
     /* Todo: Is this correct for DMG mode CGB? */
-    uint8_t scx_delay = gb->effective_scx & 7;
+    uint8_t scx_delay = (gb->effective_scx & 7) * 2;
     if (gb->cgb_double_speed) {
-        scx_delay = (scx_delay + 1) & ~1;
+        scx_delay = (scx_delay + 2) & ~3;
     }
     else {
-        scx_delay = (scx_delay + (gb->first_scanline ? 2 : 0)) & ~3;
+        scx_delay = (scx_delay + (gb->first_scanline ? 4 : 0)) & ~7;
     }
     
     /* Todo: These are correct for DMG, DMG-mode CGB, and single speed CGB. Is is correct for double speed CGB? */
-    uint8_t oam_blocking_rush = gb->cgb_double_speed? 2 : 4;
-    uint8_t vram_blocking_rush = gb->is_cgb? 0 : 4;
+    uint8_t oam_blocking_rush = gb->cgb_double_speed? 4 : 8;
+    uint8_t vram_blocking_rush = gb->is_cgb? 0 : 8;
     
     for (; cycles; cycles -= atomic_increase) {
         bool dmg_future_stat = false;
@@ -371,11 +373,11 @@ static void update_display_state(GB_gameboy_t *gb, uint8_t cycles)
         gb->stat_interrupt_line = false;
         
         gb->display_cycles += atomic_increase;
-        /* The very first line is 4 clocks shorter when the LCD turns on. Verified on SGB2, CGB in CGB mode and
+        /* The very first line is 1 M-cycle shorter when the LCD turns on. Verified on SGB2, CGB in CGB mode and
          CGB in double speed mode. */
-        if (gb->first_scanline && gb->display_cycles >= LINE_LENGTH - 8) {
+        if (gb->first_scanline && gb->display_cycles >= LINE_LENGTH - 0x10) {
             gb->first_scanline = false;
-            gb->display_cycles += 4;
+            gb->display_cycles += 8;
         }
         bool should_compare_ly = true;
         uint8_t ly_for_comparison = gb->io_registers[GB_IO_LY] = gb->display_cycles / LINE_LENGTH;
@@ -383,7 +385,7 @@ static void update_display_state(GB_gameboy_t *gb, uint8_t cycles)
         
         
         /* Handle cycle completion. STAT's initial value depends on model and mode */
-        if (gb->display_cycles == LCDC_PERIOD) {
+        if (gb->display_cycles == FRAME_LENGTH) {
             /* VBlank! */
             gb->display_cycles = 0;
             gb->io_registers[GB_IO_STAT] &= ~3;
@@ -542,11 +544,11 @@ static void update_display_state(GB_gameboy_t *gb, uint8_t cycles)
                     case 0:
                         should_compare_ly = false;
                         break;
-                    case 4:
+                    case 8:
                         gb->io_registers[GB_IO_LY] = 0;
                         ly_for_comparison = VIRTUAL_LINES - 1;
                         break;
-                    case 8:
+                    case 16:
                         gb->io_registers[GB_IO_LY] = 0;
                         should_compare_ly = false;
                         break;
@@ -561,9 +563,9 @@ static void update_display_state(GB_gameboy_t *gb, uint8_t cycles)
                     case 0:
                         ly_for_comparison = VIRTUAL_LINES - 2;
                         break;
-                    case 4:
-                        break;
                     case 8:
+                        break;
+                    case 16:
                         gb->io_registers[GB_IO_LY] = 0;
                         break;
                     default:
@@ -576,7 +578,7 @@ static void update_display_state(GB_gameboy_t *gb, uint8_t cycles)
                 switch (gb->display_cycles - (VIRTUAL_LINES - 1) * LINE_LENGTH) {
                     case 0:
                         break;
-                    case 4:
+                    case 8:
                         gb->io_registers[GB_IO_LY] = 0;
                         break;
                     default:
@@ -591,11 +593,11 @@ static void update_display_state(GB_gameboy_t *gb, uint8_t cycles)
                     case 0:
                         ly_for_comparison = VIRTUAL_LINES - 2;
                         break;
-                    case 2:
                     case 4:
-                        break;
-                    case 6:
                     case 8:
+                        break;
+                    case 12:
+                    case 16:
                         gb->io_registers[GB_IO_LY] = 0;
                         break;
                     default:
@@ -666,7 +668,7 @@ static void update_display_state(GB_gameboy_t *gb, uint8_t cycles)
        This is based on AntonioND's docs, however I could not reproduce these findings on my CGB.
        Todo: Find out why my tests contradict these docs */
     if (gb->cgb_mode && !gb->cgb_double_speed &&
-        gb->display_cycles % LINE_LENGTH == LINE_LENGTH - 4) {
+        gb->display_cycles % LINE_LENGTH == LINE_LENGTH - 8) {
         uint8_t glitch_pattern[] = {0, 0, 2, 0, 4, 4, 6, 0, 8};
         if ((gb->io_registers[GB_IO_LY] & 0xF) == 0xF) {
             gb->io_registers[GB_IO_LY] = glitch_pattern[gb->io_registers[GB_IO_LY] >> 4] << 4;
@@ -709,7 +711,7 @@ void GB_display_run(GB_gameboy_t *gb, uint8_t cycles)
 
 
     /* Render */
-    int16_t current_lcdc_x = gb->display_cycles % LINE_LENGTH - MODE2_LENGTH - (gb->effective_scx & 0x7) - 7;
+    int16_t current_lcdc_x = (gb->display_cycles % LINE_LENGTH - MODE2_LENGTH) / 2 - (gb->effective_scx & 0x7) - 7;
     
     for (;gb->previous_lcdc_x < current_lcdc_x; gb->previous_lcdc_x++) {
         if (gb->previous_lcdc_x >= WIDTH) {
diff --git a/Core/gb.c b/Core/gb.c
index 43c29806..b7aa3652 100755
--- a/Core/gb.c
+++ b/Core/gb.c
@@ -309,7 +309,7 @@ uint64_t GB_run_frame(GB_gameboy_t *gb)
     }
     gb->turbo = old_turbo;
     gb->turbo_dont_skip = old_dont_skip;
-    return gb->cycles_since_last_sync * 1000000000LL / GB_get_clock_rate(gb);
+    return gb->cycles_since_last_sync * 1000000000LL / 2 / GB_get_clock_rate(gb); /* / 2 because we use 8MHz units */
 }
 
 void GB_set_pixels_output(GB_gameboy_t *gb, uint32_t *output)
diff --git a/Core/gb.h b/Core/gb.h
index 3dea9961..7e6abb0b 100644
--- a/Core/gb.h
+++ b/Core/gb.h
@@ -267,7 +267,7 @@ struct GB_gameboy_internal_s {
         bool hdma_on;
         bool hdma_on_hblank;
         uint8_t hdma_steps_left;
-        uint16_t hdma_cycles;
+        uint16_t hdma_cycles; // in 8MHz units
         uint16_t hdma_current_src, hdma_current_dest;
 
         uint8_t dma_steps_left;
@@ -332,7 +332,7 @@ struct GB_gameboy_internal_s {
 
     /* Timing */
     GB_SECTION(timing,
-        uint32_t display_cycles;
+        uint32_t display_cycles; // In 8 MHz units
         uint32_t div_cycles;
         uint8_t tima_reload_state; /* After TIMA overflows, it becomes 0 for 4 cycles before actually reloading. */
         uint16_t serial_cycles;
@@ -418,7 +418,7 @@ struct GB_gameboy_internal_s {
                
         /* Timing */
         uint64_t last_sync;
-        uint64_t cycles_since_last_sync;
+        uint64_t cycles_since_last_sync; // In 8MHz units
 
         /* Audio */
         GB_apu_output_t apu_output;
@@ -438,8 +438,8 @@ struct GB_gameboy_internal_s {
         GB_serial_transfer_end_callback_t serial_transfer_end_callback;
                
         /* IR */
-        long cycles_since_ir_change;
-        long cycles_since_input_ir_change;
+        long cycles_since_ir_change; // In 8MHz units
+        long cycles_since_input_ir_change; // In 8MHz units
         GB_ir_queue_item_t ir_queue[GB_MAX_IR_QUEUE];
         size_t ir_queue_length;
 
@@ -493,7 +493,7 @@ struct GB_gameboy_internal_s {
         uint32_t ram_size; // Different between CGB and DMG
         uint8_t boot_rom[0x900];
         bool vblank_just_occured; // For slow operations involving syscalls; these should only run once per vblank
-        uint8_t cycles_since_run; // How many cycles have passed since the last call to GB_run()
+        uint8_t cycles_since_run; // How many cycles have passed since the last call to GB_run(), in 8MHz units
         double clock_multiplier;
    );
 };
@@ -563,7 +563,7 @@ void GB_attributed_log(GB_gameboy_t *gb, GB_log_attributes attributes, const cha
 void GB_set_pixels_output(GB_gameboy_t *gb, uint32_t *output);
 
 void GB_set_infrared_input(GB_gameboy_t *gb, bool state);
-void GB_queue_infrared_input(GB_gameboy_t *gb, bool state, long cycles_after_previous_change);
+void GB_queue_infrared_input(GB_gameboy_t *gb, bool state, long cycles_after_previous_change); /* In 8MHz units*/
     
 void GB_set_vblank_callback(GB_gameboy_t *gb, GB_vblank_callback_t callback);
 void GB_set_log_callback(GB_gameboy_t *gb, GB_log_callback_t callback);
diff --git a/Core/memory.c b/Core/memory.c
index ef2f007a..01d4a456 100644
--- a/Core/memory.c
+++ b/Core/memory.c
@@ -708,8 +708,8 @@ void GB_dma_run(GB_gameboy_t *gb)
 void GB_hdma_run(GB_gameboy_t *gb)
 {
     if (!gb->hdma_on) return;
-    while (gb->hdma_cycles >= 8) {
-        gb->hdma_cycles -= 8;
+    while (gb->hdma_cycles >= 0x10) {
+        gb->hdma_cycles -= 0x10;
 
         for (uint8_t i = 0; i < 0x10; i++) {
             GB_write_memory(gb, 0x8000 | (gb->hdma_current_dest++ & 0x1FFF), GB_read_memory(gb, (gb->hdma_current_src++)));
diff --git a/Core/timing.c b/Core/timing.c
index c03803f6..64986c0a 100644
--- a/Core/timing.c
+++ b/Core/timing.c
@@ -55,9 +55,9 @@ void GB_timing_sync(GB_gameboy_t *gb)
         return;
     }
     /* Prevent syncing if not enough time has passed.*/
-    if (gb->cycles_since_last_sync < LCDC_PERIOD / 4) return;
+    if (gb->cycles_since_last_sync < LCDC_PERIOD / 8) return;
 
-    uint64_t target_nanoseconds = gb->cycles_since_last_sync * 1000000000LL / GB_get_clock_rate(gb);
+    uint64_t target_nanoseconds = gb->cycles_since_last_sync * 1000000000LL / 2 / GB_get_clock_rate(gb); /* / 2 because we use 8MHz units */
     int64_t nanoseconds = get_nanoseconds();
     if (labs((signed long)(nanoseconds - gb->last_sync)) < target_nanoseconds ) {
         nsleep(target_nanoseconds  + gb->last_sync - nanoseconds);
@@ -145,7 +145,7 @@ void GB_advance_cycles(GB_gameboy_t *gb, uint8_t cycles)
 
     gb->debugger_ticks += cycles;
 
-    cycles >>= gb->cgb_double_speed;
+    cycles <<= !gb->cgb_double_speed;
 
     // Not affected by speed boost
     gb->hdma_cycles += cycles;