diff --git a/Cocoa/Document.m b/Cocoa/Document.m
index b278630..ea307fb 100644
--- a/Cocoa/Document.m
+++ b/Cocoa/Document.m
@@ -13,6 +13,7 @@
     unsigned long pendingLogLines;
     bool tooMuchLogs;
     bool fullScreen;
+    bool in_sync_input;
 
     NSString *lastConsoleInput;
 }
@@ -21,6 +22,7 @@
 - (void) vblank;
 - (void) log: (const char *) log withAttributes: (GB_log_attributes) attributes;
 - (const char *) getDebuggerInput;
+- (const char *) getAsyncDebuggerInput;
 @end
 
 static void vblank(GB_gameboy_t *gb)
@@ -41,6 +43,13 @@ static char *consoleInput(GB_gameboy_t *gb)
     return strdup([self getDebuggerInput]);
 }
 
+static char *asyncConsoleInput(GB_gameboy_t *gb)
+{
+    Document *self = (__bridge Document *)(gb->user_data);
+    const char *ret = [self getAsyncDebuggerInput];
+    return ret? strdup(ret) : NULL;
+}
+
 static uint32_t rgbEncode(GB_gameboy_t *gb, uint8_t r, uint8_t g, uint8_t b)
 {
     return (r << 0) | (g << 8) | (b << 16);
@@ -78,6 +87,7 @@ static uint32_t rgbEncode(GB_gameboy_t *gb, uint8_t r, uint8_t g, uint8_t b)
     GB_set_vblank_callback(&gb, (GB_vblank_callback_t) vblank);
     GB_set_log_callback(&gb, (GB_log_callback_t) consoleLog);
     GB_set_input_callback(&gb, (GB_input_callback_t) consoleInput);
+    GB_set_async_input_callback(&gb, (GB_input_callback_t) asyncConsoleInput);
     GB_set_rgb_encode_callback(&gb, rgbEncode);
     gb.user_data = (__bridge void *)(self);
 }
@@ -89,6 +99,7 @@ static uint32_t rgbEncode(GB_gameboy_t *gb, uint8_t r, uint8_t g, uint8_t b)
     GB_set_vblank_callback(&gb, (GB_vblank_callback_t) vblank);
     GB_set_log_callback(&gb, (GB_log_callback_t) consoleLog);
     GB_set_input_callback(&gb, (GB_input_callback_t) consoleInput);
+    GB_set_async_input_callback(&gb, (GB_input_callback_t) asyncConsoleInput);
     GB_set_rgb_encode_callback(&gb, rgbEncode);
     gb.user_data = (__bridge void *)(self);
 }
@@ -370,6 +381,10 @@ static uint32_t rgbEncode(GB_gameboy_t *gb, uint8_t r, uint8_t g, uint8_t b)
     else {
         line = @"";
     }
+
+    if (!in_sync_input) {
+        [self log:">"];
+    }
     [self log:[line UTF8String]];
     [self log:"\n"];
     [has_debugger_input lock];
@@ -382,10 +397,23 @@ static uint32_t rgbEncode(GB_gameboy_t *gb, uint8_t r, uint8_t g, uint8_t b)
 - (const char *) getDebuggerInput
 {
     [self log:">"];
+    in_sync_input = true;
     [has_debugger_input lockWhenCondition:1];
     NSString *input = [debugger_input_queue firstObject];
     [debugger_input_queue removeObjectAtIndex:0];
     [has_debugger_input unlockWithCondition:[debugger_input_queue count] != 0];
+    in_sync_input = false;
+    return [input UTF8String];
+}
+
+- (const char *) getAsyncDebuggerInput
+{
+    [has_debugger_input lock];
+    NSString *input = [debugger_input_queue firstObject];
+    if (input) {
+        [debugger_input_queue removeObjectAtIndex:0];
+    }
+    [has_debugger_input unlockWithCondition:[debugger_input_queue count] != 0];
     return [input UTF8String];
 }
 
diff --git a/Core/debugger.c b/Core/debugger.c
index 4babcb3..4d278a4 100644
--- a/Core/debugger.c
+++ b/Core/debugger.c
@@ -605,18 +605,29 @@ static const char *lstrip(const char *str)
     return str;
 }
 
+#define STOPPED_ONLY \
+if (!gb->debug_stopped) { \
+GB_log(gb, "Program is running. \n"); \
+return false; \
+}
+
 static bool cont(GB_gameboy_t *gb, char *arguments)
 {
+    STOPPED_ONLY
+
     if (strlen(lstrip(arguments))) {
         GB_log(gb, "Usage: continue\n");
         return true;
     }
+
     gb->debug_stopped = false;
     return false;
 }
 
 static bool next(GB_gameboy_t *gb, char *arguments)
 {
+    STOPPED_ONLY
+
     if (strlen(lstrip(arguments))) {
         GB_log(gb, "Usage: next\n");
         return true;
@@ -630,6 +641,8 @@ static bool next(GB_gameboy_t *gb, char *arguments)
 
 static bool step(GB_gameboy_t *gb, char *arguments)
 {
+    STOPPED_ONLY
+
     if (strlen(lstrip(arguments))) {
         GB_log(gb, "Usage: step\n");
         return true;
@@ -640,6 +653,8 @@ static bool step(GB_gameboy_t *gb, char *arguments)
 
 static bool finish(GB_gameboy_t *gb, char *arguments)
 {
+    STOPPED_ONLY
+
     if (strlen(lstrip(arguments))) {
         GB_log(gb, "Usage: finish\n");
         return true;
@@ -653,6 +668,8 @@ static bool finish(GB_gameboy_t *gb, char *arguments)
 
 static bool stack_leak_detection(GB_gameboy_t *gb, char *arguments)
 {
+    STOPPED_ONLY
+    
     if (strlen(lstrip(arguments))) {
         GB_log(gb, "Usage: sld\n");
         return true;
@@ -1329,6 +1346,34 @@ void GB_debugger_test_read_watchpoint(GB_gameboy_t *gb, uint16_t addr)
     _GB_debugger_test_read_watchpoint(gb, full_addr);
 }
 
+/* Returns true if debugger waits for more commands */
+bool GB_debugger_do_command(GB_gameboy_t *gb, char *input)
+{
+    if (!input[0]) {
+        return true;
+    }
+
+    char *command_string = input;
+    char *arguments = strchr(input, ' ');
+    if (arguments) {
+        /* Actually "split" the string. */
+        arguments[0] = 0;
+        arguments++;
+    }
+    else {
+        arguments = "";
+    }
+
+    const debugger_command_t *command = find_command(command_string);
+    if (command) {
+        return command->implementation(gb, arguments);
+    }
+    else {
+        GB_log(gb, "%s: no such command.\n", command_string);
+        return true;
+    }
+}
+
 void GB_debugger_run(GB_gameboy_t *gb)
 {
     char *input = NULL;
@@ -1355,34 +1400,22 @@ next_command:
         gb->debug_fin_command = false;
         gb->stack_leak_detection = false;
         input = gb->input_callback(gb);
-        if (!input[0]) {
+
+        if (GB_debugger_do_command(gb, input)) {
             goto next_command;
         }
 
-        char *command_string = input;
-        char *arguments = strchr(input, ' ');
-        if (arguments) {
-            /* Actually "split" the string. */
-            arguments[0] = 0;
-            arguments++;
-        }
-        else {
-            arguments = "";
-        }
+        free(input);
+    }
+}
 
-        const debugger_command_t *command = find_command(command_string);
-        if (command) {
-            if (command->implementation(gb, arguments)) {
-                goto next_command;
-            }
-        }
-        else {
-            GB_log(gb, "%s: no such command.\n", command_string);
-            goto next_command;
-        }
-
-        /* Split to arguments and command */
+void GB_debugger_handle_async_commands(GB_gameboy_t *gb)
+{
+    if (!gb->async_input_callback) return;
+    char *input = NULL;
 
+    while ((input = gb->async_input_callback(gb))) {
+        GB_debugger_do_command(gb, input);
         free(input);
     }
 }
diff --git a/Core/debugger.h b/Core/debugger.h
index 78f60ce..7e75185 100644
--- a/Core/debugger.h
+++ b/Core/debugger.h
@@ -3,6 +3,7 @@
 #include "gb.h"
 
 void GB_debugger_run(GB_gameboy_t *gb);
+void GB_debugger_handle_async_commands(GB_gameboy_t *gb);
 void GB_debugger_call_hook(GB_gameboy_t *gb);
 void GB_debugger_ret_hook(GB_gameboy_t *gb);
 void GB_debugger_test_write_watchpoint(GB_gameboy_t *gb, uint16_t addr, uint8_t value);
diff --git a/Core/display.c b/Core/display.c
index c83d398..06ff945 100644
--- a/Core/display.c
+++ b/Core/display.c
@@ -219,6 +219,8 @@ void display_vblank(GB_gameboy_t *gb)
             gb->last_vblank = nanoseconds;
         }
     }
+
+    gb->vblank_just_occured = true;
 }
 
 static inline uint8_t scale_channel(uint8_t x)
diff --git a/Core/gb.c b/Core/gb.c
index 82847e4..1d341e0 100644
--- a/Core/gb.c
+++ b/Core/gb.c
@@ -430,6 +430,11 @@ void GB_set_input_callback(GB_gameboy_t *gb, GB_input_callback_t callback)
     gb->input_callback = callback;
 }
 
+void GB_set_async_input_callback(GB_gameboy_t *gb, GB_input_callback_t callback)
+{
+    gb->async_input_callback = callback;
+}
+
 void GB_set_rgb_encode_callback(GB_gameboy_t *gb, GB_rgb_encode_callback_t callback)
 {
     gb->rgb_encode_callback = callback;
diff --git a/Core/gb.h b/Core/gb.h
index f5221ea..24fc291 100644
--- a/Core/gb.h
+++ b/Core/gb.h
@@ -339,6 +339,7 @@ typedef struct GB_gameboy_s {
     void *user_data;
     GB_log_callback_t log_callback;
     GB_input_callback_t input_callback;
+    GB_input_callback_t async_input_callback;
     GB_rgb_encode_callback_t rgb_encode_callback;
     GB_vblank_callback_t vblank_callback;
 
@@ -368,6 +369,7 @@ typedef struct GB_gameboy_s {
     bool turbo;
     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
 
 } GB_gameboy_t;
 
@@ -393,6 +395,7 @@ void GB_set_log_callback(GB_gameboy_t *gb, GB_log_callback_t callback);
 void GB_log(GB_gameboy_t *gb, const char *fmt, ...) __printflike(2, 3);
 void GB_attributed_log(GB_gameboy_t *gb, GB_log_attributes attributes, const char *fmt, ...) __printflike(3, 4);
 void GB_set_input_callback(GB_gameboy_t *gb, GB_input_callback_t callback);
+void GB_set_async_input_callback(GB_gameboy_t *gb, GB_input_callback_t callback);
 void GB_set_sample_rate(GB_gameboy_t *gb, unsigned int sample_rate);
 void GB_set_rgb_encode_callback(GB_gameboy_t *gb, GB_rgb_encode_callback_t callback);
 
diff --git a/Core/timing.c b/Core/timing.c
index f07858d..9390c1c 100644
--- a/Core/timing.c
+++ b/Core/timing.c
@@ -50,31 +50,30 @@ void GB_timers_run(GB_gameboy_t *gb)
             }
         }
     }
+}
 
-    /* RTC */
-    if (gb->display_cycles >= LCDC_PERIOD) { /* Time is a syscall and therefore is slow, so we update the RTC 
-                                                only during vblanks. */
-        if ((gb->rtc_high & 0x40) == 0) { /* is timer running? */
-            time_t current_time = time(NULL);
-            while (gb->last_rtc_second < current_time) {
-                gb->last_rtc_second++;
-                if (++gb->rtc_seconds == 60)
+void GB_rtc_run(GB_gameboy_t *gb)
+{
+    if ((gb->rtc_high & 0x40) == 0) { /* is timer running? */
+        time_t current_time = time(NULL);
+        while (gb->last_rtc_second < current_time) {
+            gb->last_rtc_second++;
+            if (++gb->rtc_seconds == 60)
+            {
+                gb->rtc_seconds = 0;
+                if (++gb->rtc_minutes == 60)
                 {
-                    gb->rtc_seconds = 0;
-                    if (++gb->rtc_minutes == 60)
+                    gb->rtc_minutes = 0;
+                    if (++gb->rtc_hours == 24)
                     {
-                        gb->rtc_minutes = 0;
-                        if (++gb->rtc_hours == 24)
+                        gb->rtc_hours = 0;
+                        if (++gb->rtc_days == 0)
                         {
-                            gb->rtc_hours = 0;
-                            if (++gb->rtc_days == 0)
+                            if (gb->rtc_high & 1) /* Bit 8 of days*/
                             {
-                                if (gb->rtc_high & 1) /* Bit 8 of days*/
-                                {
-                                    gb->rtc_high |= 0x80; /* Overflow bit */
-                                }
-                                gb->rtc_high ^= 1;
+                                gb->rtc_high |= 0x80; /* Overflow bit */
                             }
+                            gb->rtc_high ^= 1;
                         }
                     }
                 }
diff --git a/Core/timing.h b/Core/timing.h
index 1e41909..75e66ee 100644
--- a/Core/timing.h
+++ b/Core/timing.h
@@ -4,4 +4,5 @@
 
 void GB_advance_cycles(GB_gameboy_t *gb, uint8_t cycles);
 void GB_timers_run(GB_gameboy_t *gb);
+void GB_rtc_run(GB_gameboy_t *gb);
 #endif /* timing_h */
diff --git a/Core/z80_cpu.c b/Core/z80_cpu.c
index d253ffb..b57e979 100644
--- a/Core/z80_cpu.c
+++ b/Core/z80_cpu.c
@@ -1309,6 +1309,7 @@ static GB_opcode_t *opcodes[256] = {
 
 void GB_cpu_run(GB_gameboy_t *gb)
 {
+    gb->vblank_just_occured = false;
     bool interrupt = gb->interrupt_enable & gb->io_registers[GB_IO_IF];
     if (interrupt) {
         gb->halted = false;
@@ -1340,4 +1341,9 @@ void GB_cpu_run(GB_gameboy_t *gb)
     else {
         GB_advance_cycles(gb, 4);
     }
+
+    if (gb->vblank_just_occured) {
+        GB_rtc_run(gb);
+        GB_debugger_handle_async_commands(gb);
+    }
 }