diff --git a/32blit-pico/input/gpio.cpp b/32blit-pico/input/gpio.cpp
index ca2894261..410506def 100644
--- a/32blit-pico/input/gpio.cpp
+++ b/32blit-pico/input/gpio.cpp
@@ -88,5 +88,5 @@ void update_input() {
       new_buttons |= 1 << i;
   }
 
-  blit::api.buttons = new_buttons;
+  blit::api_data.buttons = new_buttons;
 }
diff --git a/32blit-pico/input/usb_hid.cpp b/32blit-pico/input/usb_hid.cpp
index 9bc0750ac..2ea8f3e7c 100644
--- a/32blit-pico/input/usb_hid.cpp
+++ b/32blit-pico/input/usb_hid.cpp
@@ -110,7 +110,7 @@ void update_input() {
       }
     }
 
-    api.buttons = new_buttons;
+    api_data.buttons = new_buttons;
   }
 
   if(!hid_gamepad_id)
@@ -121,19 +121,19 @@ void update_input() {
   while(mapping->id && mapping->id != hid_gamepad_id)
     mapping++;
 
-  api.buttons = dpad_map[hid_hat > 8 ? 8 : hid_hat]
-              | (hid_buttons & (1 << mapping->left)     ? uint32_t(Button::DPAD_LEFT) : 0)
-              | (hid_buttons & (1 << mapping->right)    ? uint32_t(Button::DPAD_RIGHT) : 0)
-              | (hid_buttons & (1 << mapping->up)       ? uint32_t(Button::DPAD_UP) : 0)
-              | (hid_buttons & (1 << mapping->down)     ? uint32_t(Button::DPAD_DOWN) : 0)
-              | (hid_buttons & (1 << mapping->a)        ? uint32_t(Button::A) : 0)
-              | (hid_buttons & (1 << mapping->b)        ? uint32_t(Button::B) : 0)
-              | (hid_buttons & (1 << mapping->x)        ? uint32_t(Button::X) : 0)
-              | (hid_buttons & (1 << mapping->y)        ? uint32_t(Button::Y) : 0)
-              | (hid_buttons & (1 << mapping->menu)     ? uint32_t(Button::MENU) : 0)
-              | (hid_buttons & (1 << mapping->home)     ? uint32_t(Button::HOME) : 0)
-              | (hid_buttons & (1 << mapping->joystick) ? uint32_t(Button::JOYSTICK) : 0);
-
-  api.joystick.x = (float(hid_joystick[0]) - 0x80) / 0x80;
-  api.joystick.y = (float(hid_joystick[1]) - 0x80) / 0x80;
+  api_data.buttons = dpad_map[hid_hat > 8 ? 8 : hid_hat]
+                   | (hid_buttons & (1 << mapping->left)     ? uint32_t(Button::DPAD_LEFT) : 0)
+                   | (hid_buttons & (1 << mapping->right)    ? uint32_t(Button::DPAD_RIGHT) : 0)
+                   | (hid_buttons & (1 << mapping->up)       ? uint32_t(Button::DPAD_UP) : 0)
+                   | (hid_buttons & (1 << mapping->down)     ? uint32_t(Button::DPAD_DOWN) : 0)
+                   | (hid_buttons & (1 << mapping->a)        ? uint32_t(Button::A) : 0)
+                   | (hid_buttons & (1 << mapping->b)        ? uint32_t(Button::B) : 0)
+                   | (hid_buttons & (1 << mapping->x)        ? uint32_t(Button::X) : 0)
+                   | (hid_buttons & (1 << mapping->y)        ? uint32_t(Button::Y) : 0)
+                   | (hid_buttons & (1 << mapping->menu)     ? uint32_t(Button::MENU) : 0)
+                   | (hid_buttons & (1 << mapping->home)     ? uint32_t(Button::HOME) : 0)
+                   | (hid_buttons & (1 << mapping->joystick) ? uint32_t(Button::JOYSTICK) : 0);
+
+  api_data.joystick.x = (float(hid_joystick[0]) - 0x80) / 0x80;
+  api_data.joystick.y = (float(hid_joystick[1]) - 0x80) / 0x80;
 }
diff --git a/32blit-pico/led.cpp b/32blit-pico/led.cpp
index 7fae6aa42..d6f755781 100644
--- a/32blit-pico/led.cpp
+++ b/32blit-pico/led.cpp
@@ -39,11 +39,11 @@ void update_led() {
 
 #ifdef HAVE_LED
   const float gamma = 2.8;
-  uint16_t value = (uint16_t)(std::pow((float)(api.LED.r) / 255.0f, gamma) * 65535.0f + 0.5f);
+  uint16_t value = (uint16_t)(std::pow((float)(api_data.LED.r) / 255.0f, gamma) * 65535.0f + 0.5f);
   pwm_set_gpio_level(led_pins[0], value);
-  value = (uint16_t)(std::pow((float)(api.LED.g) / 255.0f, gamma) * 65535.0f + 0.5f);
+  value = (uint16_t)(std::pow((float)(api_data.LED.g) / 255.0f, gamma) * 65535.0f + 0.5f);
   pwm_set_gpio_level(led_pins[1], value);
-  value = (uint16_t)(std::pow((float)(api.LED.b) / 255.0f, gamma) * 65535.0f + 0.5f);
+  value = (uint16_t)(std::pow((float)(api_data.LED.b) / 255.0f, gamma) * 65535.0f + 0.5f);
   pwm_set_gpio_level(led_pins[2], value);
 #endif
 }
diff --git a/32blit-pico/main.cpp b/32blit-pico/main.cpp
index 67143e150..d5c6834a6 100644
--- a/32blit-pico/main.cpp
+++ b/32blit-pico/main.cpp
@@ -99,6 +99,76 @@ static GameMetadata get_metadata() {
   return ret;
 }
 
+// blit API
+static const blit::APIConst blit_api_const {
+  blit::api_version_major, blit::api_version_minor,
+
+  ::channels,
+
+  ::set_screen_mode,
+  ::set_screen_palette,
+
+  ::now,
+  ::random,
+  nullptr, // exit
+  ::debug,
+
+  ::open_file,
+  ::read_file,
+  ::write_file,
+  ::close_file,
+  ::get_file_length,
+  ::list_files,
+  ::file_exists,
+  ::directory_exists,
+  ::create_directory,
+  ::rename_file,
+  ::remove_file,
+  ::get_save_path,
+  ::is_storage_available,
+
+  nullptr, // enable_us_timer
+  ::get_us_timer,
+  ::get_max_us_timer,
+
+  nullptr, // decode_jpeg_buffer
+  nullptr, // decode_jpeg_file
+
+  nullptr, // launch
+  nullptr, // erase_game
+  nullptr, // get_type_handler_metadata
+
+  ::get_launch_path,
+
+  ::is_multiplayer_connected,
+  ::set_multiplayer_enabled,
+  ::send_multiplayer_message,
+
+  nullptr, // flash_to_tmp
+  nullptr, // tmp_file_closed
+
+  ::get_metadata,
+
+  ::set_screen_mode_format,
+
+  nullptr, // i2c_send
+  nullptr, // i2c_recieve
+
+  nullptr, // set_raw_cdc_enabled
+  nullptr, // cdc_write
+  nullptr, // cdc_read
+
+  nullptr, // list_installed_games
+  nullptr, // can_launch
+};
+
+static blit::APIData blit_api_data;
+
+namespace blit {
+  const APIConst &api = blit_api_const;
+  APIData &api_data = blit_api_data;
+}
+
 // user funcs
 void init();
 void render(uint32_t);
@@ -141,59 +211,6 @@ int main() {
 
   stdio_init_all();
 
-  api.channels = ::channels;
-
-  api.set_screen_mode = ::set_screen_mode;
-  api.set_screen_palette = ::set_screen_palette;
-  api.set_screen_mode_format = ::set_screen_mode_format;
-  api.now = ::now;
-  api.random = ::random;
-  // api.exit = ::exit;
-
-  // serial debug
-  api.debug = ::debug;
-
-  // files
-  api.open_file = ::open_file;
-  api.read_file = ::read_file;
-  api.write_file = ::write_file;
-  api.close_file = ::close_file;
-  api.get_file_length = ::get_file_length;
-  api.list_files = ::list_files;
-  api.file_exists = ::file_exists;
-  api.directory_exists = ::directory_exists;
-  api.create_directory = ::create_directory;
-  api.rename_file = ::rename_file;
-  api.remove_file = ::remove_file;
-  api.get_save_path = ::get_save_path;
-  api.is_storage_available = ::is_storage_available;
-
-  // profiler
-  // api.enable_us_timer = ::enable_us_timer;
-  api.get_us_timer = ::get_us_timer;
-  api.get_max_us_timer = ::get_max_us_timer;
-
-  // jpeg
-  // api.decode_jpeg_buffer = ::decode_jpeg_buffer;
-  // api.decode_jpeg_file = ::decode_jpeg_file;
-
-  // launcher
-  // api.launch = ::launch;
-  // api.erase_game = ::erase_game;
-  // api.get_type_handler_metadata = ::get_type_handler_metadata;
-
-  api.get_launch_path = ::get_launch_path;
-
-  // multiplayer
-  api.is_multiplayer_connected = ::is_multiplayer_connected;
-  api.set_multiplayer_enabled = ::set_multiplayer_enabled;
-  api.send_message = ::send_multiplayer_message;
-
-  // api.flash_to_tmp = ::flash_to_tmp;
-  // api.tmp_file_closed = ::tmp_file_closed;
-
-  api.get_metadata = ::get_metadata;
-
   init_led();
   init_display();
   init_input();
diff --git a/32blit-pico/multiplayer.cpp b/32blit-pico/multiplayer.cpp
index 3def9e473..32cacf3f9 100644
--- a/32blit-pico/multiplayer.cpp
+++ b/32blit-pico/multiplayer.cpp
@@ -46,8 +46,8 @@ void update_multiplayer() {
         mp_buffer_off += usb_cdc_read(mp_buffer + mp_buffer_off, mp_buffer_len - mp_buffer_off);
 
         if(mp_buffer_off == mp_buffer_len) {
-          if(blit::api.message_received)
-            blit::api.message_received(mp_buffer, mp_buffer_len);
+          if(blit::api_data.message_received)
+            blit::api_data.message_received(mp_buffer, mp_buffer_len);
 
           delete[] mp_buffer;
           mp_buffer = nullptr;
diff --git a/32blit-sdl/Audio.cpp b/32blit-sdl/Audio.cpp
index 38dab6702..b0060377c 100644
--- a/32blit-sdl/Audio.cpp
+++ b/32blit-sdl/Audio.cpp
@@ -7,13 +7,9 @@
 #include "audio/audio.hpp"
 #include "engine/api_private.hpp"
 
-blit::AudioChannel channels[CHANNEL_COUNT];
-
 static void _audio_callback(void *userdata, uint8_t *stream, int len);
 
 Audio::Audio() {
-    blit::api.channels = channels;
-
     SDL_AudioSpec desired = {}, audio_spec = {};
 
     desired.freq = _sample_rate;
diff --git a/32blit-sdl/Multiplayer.cpp b/32blit-sdl/Multiplayer.cpp
index a12c35f57..1c41eaf34 100644
--- a/32blit-sdl/Multiplayer.cpp
+++ b/32blit-sdl/Multiplayer.cpp
@@ -25,7 +25,7 @@ Multiplayer::~Multiplayer() {
 void Multiplayer::update() {
     if(!enabled)
         return;
-  
+
     if(!socket && !listen_socket) {
         // attempt to reconnect
         auto now = SDL_GetTicks();
@@ -131,8 +131,8 @@ void Multiplayer::update() {
 
       // got message, pass to user
       if(recv_off == recv_len) {
-          if(api.message_received)
-              api.message_received(recv_buf, recv_len);
+          if(api_data.message_received)
+              api_data.message_received(recv_buf, recv_len);
 
           delete[] recv_buf;
           recv_buf = nullptr;
diff --git a/32blit-sdl/System.cpp b/32blit-sdl/System.cpp
index d005b5a48..d0014d7d5 100644
--- a/32blit-sdl/System.cpp
+++ b/32blit-sdl/System.cpp
@@ -15,6 +15,9 @@
 
 extern Input *blit_input;
 
+// blit audio channels
+static blit::AudioChannel channels[CHANNEL_COUNT];
+
 int System::width = System::max_width;
 int System::height = System::max_height;
 
@@ -168,6 +171,75 @@ void blit_send_message(const uint8_t *data, uint16_t length) {
 	blit_multiplayer->send_message(data, length);
 }
 
+// blit API
+static const blit::APIConst blit_api_const {
+  blit::api_version_major, blit::api_version_minor,
+  channels,
+
+  ::set_screen_mode,
+  ::set_screen_palette,
+
+  ::now,
+  ::blit_random,
+  nullptr, // exit
+  ::blit_debug,
+
+  ::open_file,
+  ::read_file,
+  ::write_file,
+  ::close_file,
+  ::get_file_length,
+  ::list_files,
+  ::file_exists,
+  ::directory_exists,
+  ::create_directory,
+  ::rename_file,
+  ::remove_file,
+  ::get_save_path,
+  ::is_storage_available,
+
+  ::enable_us_timer,
+  ::get_us_timer,
+  ::get_max_us_timer,
+
+  blit_decode_jpeg_buffer,
+  blit_decode_jpeg_file,
+
+  nullptr, // launch
+  nullptr, // erase_game
+  nullptr, // get_type_handler_metadata
+
+  ::get_launch_path,
+
+  blit_is_multiplayer_connected,
+  blit_set_multiplayer_enabled,
+  blit_send_message,
+
+  nullptr, // flash_to_tmp
+  nullptr, // tmp_file_closed
+
+  ::get_metadata,
+
+  ::set_screen_mode_format,
+
+  nullptr, // i2c_send
+  nullptr, // i2c_recieve
+
+  nullptr, // set_raw_cdc_enabled
+  nullptr, // cdc_write
+  nullptr, // cdc_read
+
+  nullptr, // list_installed_games
+  nullptr, // can_launch
+};
+
+static blit::APIData blit_api_data;
+
+namespace blit {
+  const APIConst &api = blit_api_const;
+  APIData &api_data = blit_api_data;
+}
+
 // SDL events
 const Uint32 System::timer_event = SDL_RegisterEvents(2);
 const Uint32 System::loop_event = System::timer_event + 1;
@@ -208,46 +280,11 @@ void System::run() {
 
 	start = std::chrono::steady_clock::now();
 
-	blit::api.now = ::now;
-	blit::api.random = ::blit_random;
-	blit::api.debug = ::blit_debug;
-	blit::api.set_screen_mode = ::set_screen_mode;
-	blit::api.set_screen_palette = ::set_screen_palette;
-  blit::api.set_screen_mode_format = ::set_screen_mode_format;
 	blit::update = ::update;
 	blit::render = ::render;
 
 	setup_base_path();
 
-	blit::api.open_file = ::open_file;
-	blit::api.read_file = ::read_file;
-	blit::api.write_file = ::write_file;
-	blit::api.close_file = ::close_file;
-	blit::api.get_file_length = ::get_file_length;
-	blit::api.list_files = ::list_files;
-	blit::api.file_exists = ::file_exists;
-	blit::api.directory_exists = ::directory_exists;
-	blit::api.create_directory = ::create_directory;
-	blit::api.rename_file = ::rename_file;
-	blit::api.remove_file = ::remove_file;
-	blit::api.get_save_path = ::get_save_path;
-	blit::api.is_storage_available = ::is_storage_available;
-
-	blit::api.enable_us_timer = ::enable_us_timer;
-	blit::api.get_us_timer = ::get_us_timer;
-	blit::api.get_max_us_timer = ::get_max_us_timer;
-
-	blit::api.decode_jpeg_buffer = blit_decode_jpeg_buffer;
-	blit::api.decode_jpeg_file = blit_decode_jpeg_file;
-
-  blit::api.get_launch_path = ::get_launch_path;
-
-	blit::api.is_multiplayer_connected = blit_is_multiplayer_connected;
-	blit::api.set_multiplayer_enabled = blit_set_multiplayer_enabled;
-	blit::api.send_message = blit_send_message;
-
-  blit::api.get_metadata = ::get_metadata;
-
 	blit::set_screen_mode(blit::lores);
 
 #ifdef __EMSCRIPTEN__
diff --git a/32blit-stm32/CMakeLists.txt b/32blit-stm32/CMakeLists.txt
index db87ea987..33b1c09f8 100644
--- a/32blit-stm32/CMakeLists.txt
+++ b/32blit-stm32/CMakeLists.txt
@@ -55,6 +55,7 @@ add_library(BlitHalSTM32 OBJECT
 	Middlewares/ST/STM32_USB_Host_Library/Class/CDC/Src/usbh_cdc.c
 	Src/usbd_msc_scsi.c
 	Src/system_stm32h7xx.c
+	Src/api.cpp
 	Src/fatfs.cpp
 	Src/fatfs_sd.c
 	Src/usb_otg.c
diff --git a/32blit-stm32/Src/32blit.cpp b/32blit-stm32/Src/32blit.cpp
index 2a7bdd7c9..be3659a20 100644
--- a/32blit-stm32/Src/32blit.cpp
+++ b/32blit-stm32/Src/32blit.cpp
@@ -71,19 +71,19 @@ void DFUBoot(void)
 
 static void init_api_shared() {
   // Reset button state, this prevents the user app immediately seeing the last button transition used to launch the game
-  api.buttons.state = 0;
-  api.buttons.pressed = 0;
-  api.buttons.released = 0;
+  api_data.buttons.state = 0;
+  api_data.buttons.pressed = 0;
+  api_data.buttons.released = 0;
 
   // reset shared outputs
-  api.vibration = 0.0f;
-  api.LED = Pen();
+  api_data.vibration = 0.0f;
+  api_data.LED = Pen();
 
   for(int i = 0; i < CHANNEL_COUNT; i++)
     api.channels[i] = AudioChannel();
 
-  api.message_received = nullptr;
-  api.i2c_completed = nullptr;
+  api_data.message_received = nullptr;
+  api_data.i2c_completed = nullptr;
 
   // take CDC back
   g_commandStream.SetParsingEnabled(true);
@@ -362,17 +362,20 @@ void blit_init() {
 
   i2c::init();
 
-  blit::api.version_major = api_version_major;
-  blit::api.version_minor = api_version_minor;
+  // bit of a hack, but we know it's writable
+  auto &api = *(APIConst *)&blit::api;
 
-  blit::api.debug = blit_debug;
-  blit::api.now = HAL_GetTick;
-  blit::api.random = HAL_GetRandom;
-  blit::api.exit = blit_exit;
+  api.version_major = api_version_major;
+  api.version_minor = api_version_minor;
 
-  blit::api.set_screen_mode = display::set_screen_mode;
-  blit::api.set_screen_palette = display::set_screen_palette;
-  blit::api.set_screen_mode_format = display::set_screen_mode_format;
+  api.debug = blit_debug;
+  api.now = HAL_GetTick;
+  api.random = HAL_GetRandom;
+  api.exit = blit_exit;
+
+  api.set_screen_mode = display::set_screen_mode;
+  api.set_screen_palette = display::set_screen_palette;
+  api.set_screen_mode_format = display::set_screen_mode_format;
 
   display::set_screen_mode(blit::lores);
 
@@ -380,43 +383,43 @@ void blit_init() {
   blit::render = ::render;
   blit::init   = ::init;
 
-  blit::api.open_file = ::open_file;
-  blit::api.read_file = ::read_file;
-  blit::api.write_file = ::write_file;
-  blit::api.close_file = ::close_file;
-  blit::api.get_file_length = ::get_file_length;
-  blit::api.list_files = ::list_files;
-  blit::api.file_exists = ::file_exists;
-  blit::api.directory_exists = ::directory_exists;
-  blit::api.create_directory = ::create_directory;
-  blit::api.rename_file = ::rename_file;
-  blit::api.remove_file = ::remove_file;
-  blit::api.get_save_path = ::get_save_path;
-  blit::api.is_storage_available = blit_sd_mounted;
+  api.open_file = ::open_file;
+  api.read_file = ::read_file;
+  api.write_file = ::write_file;
+  api.close_file = ::close_file;
+  api.get_file_length = ::get_file_length;
+  api.list_files = ::list_files;
+  api.file_exists = ::file_exists;
+  api.directory_exists = ::directory_exists;
+  api.create_directory = ::create_directory;
+  api.rename_file = ::rename_file;
+  api.remove_file = ::remove_file;
+  api.get_save_path = ::get_save_path;
+  api.is_storage_available = blit_sd_mounted;
 
-  blit::api.enable_us_timer = ::enable_us_timer;
-  blit::api.get_us_timer = ::get_us_timer;
-  blit::api.get_max_us_timer = ::get_max_us_timer;
+  api.enable_us_timer = ::enable_us_timer;
+  api.get_us_timer = ::get_us_timer;
+  api.get_max_us_timer = ::get_max_us_timer;
 
-  blit::api.decode_jpeg_buffer = blit_decode_jpeg_buffer;
-  blit::api.decode_jpeg_file = blit_decode_jpeg_file;
+  api.decode_jpeg_buffer = blit_decode_jpeg_buffer;
+  api.decode_jpeg_file = blit_decode_jpeg_file;
 
-  blit::api.get_launch_path = ::get_launch_path;
+  api.get_launch_path = ::get_launch_path;
 
-  blit::api.is_multiplayer_connected = multiplayer::is_connected;
-  blit::api.set_multiplayer_enabled = multiplayer::set_enabled;
-  blit::api.send_message = multiplayer::send_message;
+  api.is_multiplayer_connected = multiplayer::is_connected;
+  api.set_multiplayer_enabled = multiplayer::set_enabled;
+  api.send_message = multiplayer::send_message;
 
-  blit::api.get_metadata = ::get_metadata;
+  api.get_metadata = ::get_metadata;
 
-  blit::api.tick_function_changed = false;
+  api_data.tick_function_changed = false;
 
-  blit::api.i2c_send = i2c::user_send;
-  blit::api.i2c_receive = i2c::user_receive;
+  api.i2c_send = i2c::user_send;
+  api.i2c_receive = i2c::user_receive;
 
-  blit::api.set_raw_cdc_enabled = set_raw_cdc_enabled;
-  blit::api.cdc_write = cdc_write;
-  blit::api.cdc_read = cdc_read;
+  api.set_raw_cdc_enabled = set_raw_cdc_enabled;
+  api.cdc_write = cdc_write;
+  api.cdc_read = cdc_read;
 
   display::init();
 
@@ -492,7 +495,7 @@ void blit_menu() {
     if (user_tick && !user_code_disabled) {
       // user code was running
       do_tick = user_tick;
-      api.tick_function_changed = true;
+      api_data.tick_function_changed = true;
       blit::render = user_render;
     } else {
       blit::update = ::update;
@@ -513,7 +516,7 @@ void blit_menu() {
     blit::update = blit_menu_update;
     blit::render = blit_menu_render;
     do_tick = blit::tick;
-    api.tick_function_changed = true;
+    api_data.tick_function_changed = true;
 
     if(screen.format == PixelFormat::P) {
       memcpy(menu_saved_colours, screen.palette, num_menu_colours * sizeof(Pen));
@@ -671,7 +674,7 @@ bool blit_switch_execution(uint32_t address, bool force_game)
     blit::render = ::render;
     blit::update = ::update;
     do_tick = blit::tick;
-    api.tick_function_changed = true;
+    api_data.tick_function_changed = true;
 
     cached_file_in_tmp = false;
     close_open_files();
@@ -741,7 +744,7 @@ void blit_enable_user_code() {
     return;
 
   do_tick = user_tick;
-  api.tick_function_changed = true;
+  api_data.tick_function_changed = true;
   blit::render = user_render;
   user_code_disabled = false;
   sound::enabled = true;
@@ -752,7 +755,7 @@ void blit_disable_user_code() {
     return;
 
   do_tick = blit::tick;
-  api.tick_function_changed = true;
+  api_data.tick_function_changed = true;
   blit::render = ::render;
   sound::enabled = false;
   user_code_disabled = true;
diff --git a/32blit-stm32/Src/32blit/i2c.cpp b/32blit-stm32/Src/32blit/i2c.cpp
index 679da2179..bad611a32 100644
--- a/32blit-stm32/Src/32blit/i2c.cpp
+++ b/32blit-stm32/Src/32blit/i2c.cpp
@@ -186,8 +186,8 @@ namespace i2c {
       {
         auto addr = user_addr;
         user_addr = 0;
-        if(api.i2c_completed && !blit_user_code_disabled())
-          api.i2c_completed(addr, user_reg, user_buf, user_buf_len);
+        if(api_data.i2c_completed && !blit_user_code_disabled())
+          api_data.i2c_completed(addr, user_reg, user_buf, user_buf_len);
 
         blit_i2c_delay(16, SEND_ACL);
         break;
diff --git a/32blit-stm32/Src/api.cpp b/32blit-stm32/Src/api.cpp
new file mode 100644
index 000000000..3e204ec06
--- /dev/null
+++ b/32blit-stm32/Src/api.cpp
@@ -0,0 +1,14 @@
+#include "engine/api_private.hpp"
+
+extern char __api_start;
+#pragma GCC diagnostic ignored "-Warray-bounds"
+
+#ifndef BLIT_API_SPLIT_COMPAT
+#error "BLIT_API_SPLIT_COMPAT not set!"
+#endif
+
+namespace blit {
+  // for compatibility reasons, these are the same thing
+  const APIConst &api = *(APIConst *)&__api_start;
+  APIData &api_data = *(APIData *)&__api_start;
+}
diff --git a/32blit-stm32/Src/multiplayer.cpp b/32blit-stm32/Src/multiplayer.cpp
index 75356b95b..aa896ca5c 100644
--- a/32blit-stm32/Src/multiplayer.cpp
+++ b/32blit-stm32/Src/multiplayer.cpp
@@ -41,8 +41,8 @@ namespace multiplayer {
 
       // done, send to user
       if(read == length) {
-        if(api.message_received && enabled)
-          api.message_received(buf, length);
+        if(api_data.message_received && enabled)
+          api_data.message_received(buf, length);
 
         delete[] buf;
         buf = nullptr;
diff --git a/32blit-stm32/Src/sound.cpp b/32blit-stm32/Src/sound.cpp
index 306907e49..32aa19932 100644
--- a/32blit-stm32/Src/sound.cpp
+++ b/32blit-stm32/Src/sound.cpp
@@ -36,7 +36,7 @@ namespace sound {
   bool enabled = true;
 
   void init() {
-    blit::api.channels = channels;
+    ((APIConst *) &blit::api)->channels = channels;
 
     // setup the 22,010Hz audio timer
     HAL_NVIC_EnableIRQ(TIM6_DAC_IRQn);
diff --git a/32blit-stm32/executable.cmake b/32blit-stm32/executable.cmake
index 3ffc25567..aee239e5a 100644
--- a/32blit-stm32/executable.cmake
+++ b/32blit-stm32/executable.cmake
@@ -1,7 +1,7 @@
 set(MCU_LINKER_SCRIPT "${CMAKE_CURRENT_LIST_DIR}/${MCU_LINKER_SCRIPT}")
 set(HAL_DIR ${CMAKE_CURRENT_LIST_DIR})
 
-set(USER_STARTUP ${CMAKE_CURRENT_LIST_DIR}/startup_user.S ${CMAKE_CURRENT_LIST_DIR}/startup_user.cpp)
+set(USER_STARTUP ${CMAKE_CURRENT_LIST_DIR}/startup_user.S ${CMAKE_CURRENT_LIST_DIR}/startup_user.cpp ${CMAKE_CURRENT_LIST_DIR}/Src/api.cpp)
 
 function(blit_executable_common NAME)
 	target_link_libraries(${NAME} BlitEngine)
diff --git a/32blit.toolchain b/32blit.toolchain
index 98f5fa514..5d2fde5ae 100644
--- a/32blit.toolchain
+++ b/32blit.toolchain
@@ -20,7 +20,7 @@ endif ()
 
 set(CDC_FIFO_BUFFERS 64)
 
-set(COMMON_FLAGS "${MCU_FLAGS} -fsingle-precision-constant -Wall -fdata-sections -ffunction-sections -Wattributes -Wdouble-promotion -Werror=double-promotion -mno-pic-data-is-text-relative -mno-single-pic-base")
+set(COMMON_FLAGS "${MCU_FLAGS} -fsingle-precision-constant -Wall -fdata-sections -ffunction-sections -Wattributes -Wdouble-promotion -Werror=double-promotion -mno-pic-data-is-text-relative -mno-single-pic-base -DBLIT_API_SPLIT_COMPAT")
 
 set(CMAKE_C_FLAGS_INIT "${COMMON_FLAGS}")
 set(CMAKE_CXX_FLAGS_INIT "${COMMON_FLAGS} -fno-exceptions")
diff --git a/32blit/audio/audio.hpp b/32blit/audio/audio.hpp
index ae41008ee..513f14932 100644
--- a/32blit/audio/audio.hpp
+++ b/32blit/audio/audio.hpp
@@ -127,7 +127,7 @@ namespace blit {
 	    }
   };
 
-  extern AudioChannel *&channels;
+  extern AudioChannel * const &channels;
 
   uint16_t get_audio_frame();
   bool is_audio_playing();
diff --git a/32blit/engine/api.cpp b/32blit/engine/api.cpp
index b5fe943a9..d7afe9249 100644
--- a/32blit/engine/api.cpp
+++ b/32blit/engine/api.cpp
@@ -1,28 +1,16 @@
 #include "api.hpp"
 #include "api_private.hpp"
 
-#ifdef TARGET_32BLIT_HW
-extern char __api_start;
-#pragma GCC diagnostic ignored "-Warray-bounds"
-#endif
-
 namespace blit {
-#ifdef TARGET_32BLIT_HW
-  API &api = *(API *)&__api_start;
-#else
-  API real_api;
-  API &api = real_api;
-#endif
-
-  static_assert(sizeof(API) < 2048);
+  static_assert(sizeof(APIConst) < 2048);
 
-  ButtonState &buttons = api.buttons;
-  float &hack_left = api.hack_left;
-  float &hack_right = api.hack_right;
-  float &vibration = api.vibration;
-  Vec2 &joystick = api.joystick;
-  Vec3 &tilt = api.tilt;
-  Pen &LED = api.LED;
+  ButtonState &buttons = api_data.buttons;
+  float &hack_left = api_data.hack_left;
+  float &hack_right = api_data.hack_right;
+  float &vibration = api_data.vibration;
+  Vec2 &joystick = api_data.joystick;
+  Vec3 &tilt = api_data.tilt;
+  Pen &LED = api_data.LED;
 
-  AudioChannel *&channels = api.channels;
-}
\ No newline at end of file
+  AudioChannel * const &channels = api.channels;
+}
diff --git a/32blit/engine/api_private.hpp b/32blit/engine/api_private.hpp
index 4be7a539b..14d09b859 100644
--- a/32blit/engine/api_private.hpp
+++ b/32blit/engine/api_private.hpp
@@ -14,6 +14,13 @@
 #include "../types/vec2.hpp"
 #include "../types/vec3.hpp"
 
+// compatibility with API layout before const/data split
+#ifdef BLIT_API_SPLIT_COMPAT
+#define COMPAT_PAD(type, name, size) type name[size]
+#else
+#define COMPAT_PAD(type, name, size)
+#endif
+
 namespace blit {
 
   using AllocateCallback = uint8_t *(*)(size_t);
@@ -62,17 +69,11 @@ namespace blit {
   };
 
   #pragma pack(push, 4)
-  struct API {
+  struct APIConst {
     uint16_t version_major;
     uint16_t version_minor;
 
-    ButtonState buttons;
-    float hack_left;
-    float hack_right;
-    float vibration;
-    Vec2 joystick;
-    Vec3 tilt;
-    Pen LED;
+    COMPAT_PAD(uint8_t, pad, 48); // was data
 
     AudioChannel *channels;
 
@@ -120,21 +121,21 @@ namespace blit {
     bool (*is_multiplayer_connected)();
     void (*set_multiplayer_enabled)(bool enabled);
     void (*send_message)(const uint8_t *data, uint16_t len);
-    void (*message_received)(const uint8_t *data, uint16_t len); // set by user
+    COMPAT_PAD(uintptr_t, pad2, 1); // was message_recieved
 
     const uint8_t *(*flash_to_tmp)(const std::string &filename, uint32_t &size);
     void (*tmp_file_closed)(const uint8_t *ptr);
 
     GameMetadata (*get_metadata)();
 
-    bool tick_function_changed;
+    COMPAT_PAD(uint8_t, pad3, 1); // was data
 
     bool (*set_screen_mode_format)(ScreenMode new_mode, SurfaceTemplate &new_surf_template);
 
     // raw i2c access
     bool (*i2c_send)(uint8_t address, uint8_t reg, const uint8_t *data, uint16_t len);
     bool (*i2c_receive)(uint8_t address, uint8_t reg, uint8_t *data, uint16_t len);
-    void (*i2c_completed)(uint8_t address, uint8_t reg, const uint8_t *data, uint16_t len); // callback when done
+    COMPAT_PAD(uintptr_t, pad4, 1); // was i2c_completed
 
     // raw cdc
     bool (*set_raw_cdc_enabled)(bool enabled);
@@ -147,7 +148,43 @@ namespace blit {
     // files this returns success for should be .blit files or have a registered handler (get_type_handler_metadata should return valid metadata)
     CanLaunchResult (*can_launch)(const char *path);
   };
+
+  struct APIData {
+    uint16_t pad[2];
+
+    ButtonState buttons;
+    float hack_left;
+    float hack_right;
+    float vibration;
+    Vec2 joystick;
+    Vec3 tilt;
+    Pen LED;
+
+    COMPAT_PAD(uintptr_t, pad2, 32);
+
+    // multiplayer
+    void (*message_received)(const uint8_t *data, uint16_t len); // set by user
+
+    COMPAT_PAD(uintptr_t, pad3, 3);
+
+    bool tick_function_changed;
+
+    COMPAT_PAD(uintptr_t, pad4, 3);
+
+    // raw i2c access
+    void (*i2c_completed)(uint8_t address, uint8_t reg, const uint8_t *data, uint16_t len); // callback when done
+
+    COMPAT_PAD(uintptr_t, pad5, 5);
+  };
+
   #pragma pack(pop)
 
-  extern API &api;
+#ifdef BLIT_API_SPLIT_COMPAT
+  static_assert(sizeof(APIConst) == sizeof(APIData));
+#else
+  static_assert(sizeof(APIData) <= 256);
+#endif
+
+  extern const APIConst &api;
+  extern APIData &api_data;
 }
diff --git a/32blit/engine/engine.cpp b/32blit/engine/engine.cpp
index 80b1679b0..ba34c1e92 100644
--- a/32blit/engine/engine.cpp
+++ b/32blit/engine/engine.cpp
@@ -107,7 +107,7 @@ namespace blit {
     }
 
     // skip time where this wasn't the active tick function (menu/game switches)
-    if (api.tick_function_changed) {
+    if (api_data.tick_function_changed) {
       auto skipped_time = time - last_tick_time;
       last_tick_time = time;
 
@@ -121,7 +121,7 @@ namespace blit {
         tween->paused += skipped_time;
       }
 
-      api.tick_function_changed = false;
+      api_data.tick_function_changed = false;
     }
 
     // update timers
@@ -132,11 +132,11 @@ namespace blit {
     pending_update_time += (time - last_tick_time);
     while (pending_update_time >= update_rate_ms) {
       // button state changes
-      uint32_t changed = api.buttons.state ^ last_state;
+      uint32_t changed = api_data.buttons.state ^ last_state;
 
-      api.buttons.pressed = changed & api.buttons.state;
-      api.buttons.released = changed & last_state;
-      last_state = api.buttons.state;
+      api_data.buttons.pressed = changed & api_data.buttons.state;
+      api_data.buttons.released = changed & last_state;
+      last_state = api_data.buttons.state;
 
       update(time - pending_update_time); // create fake timestamp that would have been accurate for the update event
       pending_update_time -= update_rate_ms;
diff --git a/32blit/engine/multiplayer.cpp b/32blit/engine/multiplayer.cpp
index 3dc8b85a2..9aa3b2edb 100644
--- a/32blit/engine/multiplayer.cpp
+++ b/32blit/engine/multiplayer.cpp
@@ -18,5 +18,5 @@ namespace blit {
     api.send_message(data, len);
   }
 
-  void (*&message_received)(const uint8_t *data, uint16_t len) = api.message_received;
-}
\ No newline at end of file
+  void (*&message_received)(const uint8_t *data, uint16_t len) = api_data.message_received;
+}
diff --git a/firmware/firmware.cpp b/firmware/firmware.cpp
index 85acde332..08f0bb96f 100644
--- a/firmware/firmware.cpp
+++ b/firmware/firmware.cpp
@@ -690,6 +690,10 @@ static void start_launcher() {
 }
 
 void init() {
+  // bit of a hack, but we know it's writable
+  // ... or is the fact part of the "const" api is set much later, the bigger hack?
+  auto &api = *(APIConst *)&blit::api;
+
   api.launch = launch_file_from_sd;
   api.erase_game = erase_flash_game;
   api.get_type_handler_metadata = get_type_handler_metadata;