diff --git a/1bpp.py b/1bpp.py
new file mode 100644
index 0000000..1d00cca
--- /dev/null
+++ b/1bpp.py
@@ -0,0 +1,31 @@
+import sys
+
+width = 640
+height = 480
+
+with open(sys.argv[1], 'rb') as f:
+    b = f.read()
+    assert len(b) == width * height, len(b)
+
+buf = []
+
+for i in range(len(b) // 8):
+    ix = i * 8
+    px = b[ix:ix + 8]
+    assert all(p in {0, 1} for p in px)
+    out = (
+          (px[0] << 7)
+        | (px[1] << 6)
+        | (px[2] << 5)
+        | (px[3] << 4)
+        | (px[4] << 3)
+        | (px[5] << 2)
+        | (px[6] << 1)
+        | (px[7] << 0)
+    )
+    buf.append(out)
+
+assert len(buf) == width * height // 8
+
+with open(sys.argv[2], 'wb') as f:
+    f.write(bytes(buf))
diff --git a/Makefile b/Makefile
index 20c0f6e..58af89d 100644
--- a/Makefile
+++ b/Makefile
@@ -13,7 +13,7 @@ MAIN_OBJ = \
 	holly/region_array.o \
 	holly/ta_fifo_polygon_converter.o \
 	holly/core.o \
-	maple.o \
+	maple/maple.o \
 	scene.o \
 	macaw.data.o \
 	$(LIBGCC)
diff --git a/holly/float_uint32.h b/float_uint32.h
similarity index 100%
rename from holly/float_uint32.h
rename to float_uint32.h
diff --git a/holly/core.cpp b/holly/core.cpp
index 5ef0b97..8aa531e 100644
--- a/holly/core.cpp
+++ b/holly/core.cpp
@@ -1,4 +1,4 @@
-#include "float_uint32.h"
+#include "../float_uint32.h"
 #include "core_bits.h"
 #include "../holly.h"
 #include "../memorymap.h"
diff --git a/holly/core_bits.h b/holly/core_bits.h
index 5761bde..772da55 100644
--- a/holly/core_bits.h
+++ b/holly/core_bits.h
@@ -1,6 +1,6 @@
 #include <cstdint>
 
-#include "float_uint32.h"
+#include "../float_uint32.h"
 
 namespace id {
   constexpr uint32_t device_id(uint32_t reg) { return (reg >> 16) & 0xffff; }
diff --git a/holly/ta_bits.h b/holly/ta_bits.h
index 40d84d0..ce28ee6 100644
--- a/holly/ta_bits.h
+++ b/holly/ta_bits.h
@@ -1,6 +1,6 @@
 #include <cstdint>
 
-#include "float_uint32.h"
+#include "../float_uint32.h"
 
 namespace ta_ol_base {
   constexpr uint32_t base_address(uint32_t num) { return (num & 0xffffe0) << 0; }
diff --git a/holly/ta_parameter.h b/holly/ta_parameter.h
index c304c2e..963c33e 100644
--- a/holly/ta_parameter.h
+++ b/holly/ta_parameter.h
@@ -1,7 +1,7 @@
 #include <cstdint>
 #include <cstddef>
 
-#include "float_uint32.h"
+#include "../float_uint32.h"
 #include "isp_tsp.h"
 
 namespace para_control {
diff --git a/main.cpp b/main.cpp
index 800f457..d3dd88e 100644
--- a/main.cpp
+++ b/main.cpp
@@ -9,8 +9,8 @@
 #include "holly/core_bits.h"
 #include "holly/ta_fifo_polygon_converter.h"
 #include "systembus.h"
-#include "maple.h"
-#include "maple_bits.h"
+#include "maple/maple.h"
+#include "maple/maple_bits.h"
 
 #include "holly/texture_memory_alloc.h"
 
diff --git a/maple.cpp b/maple/maple.cpp
similarity index 71%
rename from maple.cpp
rename to maple/maple.cpp
index a8cb9c6..77fb592 100644
--- a/maple.cpp
+++ b/maple/maple.cpp
@@ -1,12 +1,13 @@
 #include <cstdint>
 #include <bit>
 
-#include "sh7091.h"
-#include "sh7091_bits.h"
-#include "systembus.h"
-#include "systembus_bits.h"
-#include "maple_bits.h"
+#include "../sh7091.h"
+#include "../sh7091_bits.h"
+#include "../systembus.h"
+#include "../systembus_bits.h"
 
+#include "maple_bits.h"
+#include "maple_bus_commands.h"
 #include "maple.h"
 
 #define AP__PO__A (0b00 << 6)
@@ -30,32 +31,31 @@
 #define HOST_INSTRUCTION__PORT_SELECT__D (0b11 << 16)
 #define HOST_INSTRUCTION__TRANSFER_LENGTH(n) (((n) & 0xff) << 0)
 
-template <int N>
+template <typename T>
 struct maple_host_command {
   uint32_t host_instruction;
   uint32_t receive_data_storage_address;
-  uint32_t protocol_data[N];
+  uint8_t command_code;
+  uint8_t destination_ap;
+  uint8_t source_ap;
+  uint8_t data_size;
+  T data_fields;
 };
 
 void maple_init_host_command(uint32_t * buf, uint32_t * receive_address)
 {
-  auto command = reinterpret_cast<maple_host_command<1> *>(buf);
+  auto host_command = reinterpret_cast<maple_host_command<device_request::data_fields> *>(buf);
 
-  command->host_instruction = HOST_INSTRUCTION__END_FLAG
-			    | HOST_INSTRUCTION__PORT_SELECT__A
-			    | HOST_INSTRUCTION__TRANSFER_LENGTH(0); // 4 bytes
+  host_command->host_instruction = HOST_INSTRUCTION__END_FLAG
+                                 | HOST_INSTRUCTION__PORT_SELECT__A
+                                 | HOST_INSTRUCTION__TRANSFER_LENGTH(0); // 4 bytes
 
-  command->receive_data_storage_address = reinterpret_cast<uint32_t>(receive_address);
+  host_command->receive_data_storage_address = reinterpret_cast<uint32_t>(receive_address);
 
-  uint32_t command_code = 0x01; // 'Device Request'
-  uint32_t destination_ap = AP__DE__DEVICE | AP__PO__A;
-  uint32_t source_ap = AP__PO__A;
-  uint32_t data_size = 0;
-  // maple bus is big endian
-  command->protocol_data[0] = std::byteswap( (command_code << 24)
-					   | (destination_ap << 16)
-					   | (source_ap << 8)
-					   | (data_size << 0));
+  host_command->command_code = device_request::command_code;
+  host_command->destination_ap = AP__DE__DEVICE | AP__PO__A;
+  host_command->source_ap = AP__PO__A;
+  host_command->data_size = 0;
 }
 
 void maple_dma_start(uint32_t * command_buf)
diff --git a/maple.h b/maple/maple.h
similarity index 100%
rename from maple.h
rename to maple/maple.h
diff --git a/maple_bits.h b/maple/maple_bits.h
similarity index 98%
rename from maple_bits.h
rename to maple/maple_bits.h
index 9343e3d..860786a 100644
--- a/maple_bits.h
+++ b/maple/maple_bits.h
@@ -1,6 +1,6 @@
 #include <cstdint>
 
-#include "holly/float_uint32.h"
+#include "../float_uint32.h"
 
 namespace mdstar {
   constexpr uint32_t table_address(uint32_t num) { return (num & 0xfffffe0) << 0; }
@@ -31,12 +31,12 @@ namespace mdst {
 namespace msys {
   constexpr uint32_t time_out_counter(uint32_t num) { return (num & 0xffff) << 16; }
   constexpr uint32_t single_hard_trigger = 1 << 12;
-  
+
   namespace sending_rate {
     constexpr uint32_t _2M = 0 << 8;
     constexpr uint32_t _1M = 1 << 8;
   }
-  
+
   constexpr uint32_t delay_time(uint32_t num) { return (num & 0xf) << 0; }
 }
 
@@ -75,4 +75,3 @@ namespace mrxdad {
 namespace mrxdbd {
   constexpr uint32_t rxd_base_address(uint32_t reg) { return (reg >> 0) & 0x1fffffff; }
 }
-
diff --git a/maple/maple_bus_commands.h b/maple/maple_bus_commands.h
new file mode 100644
index 0000000..259b86c
--- /dev/null
+++ b/maple/maple_bus_commands.h
@@ -0,0 +1,231 @@
+#include <cstdint>
+
+namespace device_request {
+  constexpr uint32_t command_code = 0x1;
+  
+  struct data_fields {
+  };
+}
+
+namespace all_status_request {
+  constexpr uint32_t command_code = 0x2;
+  
+  struct data_fields {
+  };
+}
+
+namespace device_reset {
+  constexpr uint32_t command_code = 0x3;
+  
+  struct data_fields {
+  };
+}
+
+namespace device_kill {
+  constexpr uint32_t command_code = 0x4;
+  
+  struct data_fields {
+  };
+}
+
+namespace device_status {
+  constexpr uint32_t command_code = 0x5;
+  
+  struct data_fields {
+    uint8_t device_id[16];
+    uint8_t destination_code[1];
+    uint8_t connection_direction[1];
+    uint8_t product_name[30];
+    uint8_t license[60];
+    uint8_t low_consumption_standby_current[2];
+    uint8_t maximum_current_consumption[2];
+  };
+  
+  static_assert((sizeof (struct data_fields)) == 112);
+}
+
+namespace device_all_status {
+  constexpr uint32_t command_code = 0x6;
+  
+  template <int N>
+  struct data_fields {
+    uint8_t device_id[16];
+    uint8_t destination_code[1];
+    uint8_t connection_direction[1];
+    uint8_t product_name[30];
+    uint8_t license[60];
+    uint8_t low_consumption_standby_current[2];
+    uint8_t maximum_current_consumption[2];
+    uint8_t free_device_status[N];
+  };
+  
+  static_assert((sizeof (struct data_fields<0>)) == 112);
+}
+
+namespace device_reply {
+  constexpr uint32_t command_code = 0x7;
+  
+  struct data_fields {
+  };
+}
+
+namespace data_transfer {
+  constexpr uint32_t command_code = 0x8;
+  
+  template <int N>
+  struct data_fields {
+    uint8_t data[N];
+  };
+  
+  static_assert((sizeof (struct data_fields<0>)) == 0);
+}
+
+namespace get_condition {
+  constexpr uint32_t command_code = 0x9;
+  
+  struct data_fields {
+    uint8_t function_type[4];
+  };
+  
+  static_assert((sizeof (struct data_fields)) == 4);
+}
+
+namespace get_media_info {
+  constexpr uint32_t command_code = 0xa;
+  
+  struct data_fields {
+    uint8_t function_type[4];
+    uint8_t pt[4];
+  };
+  
+  static_assert((sizeof (struct data_fields)) == 8);
+}
+
+namespace block_read {
+  constexpr uint32_t command_code = 0xb;
+  
+  struct data_fields {
+    uint8_t function_type[4];
+    uint8_t pt[1];
+    uint8_t phase[1];
+    uint8_t block_no[2];
+  };
+  
+  static_assert((sizeof (struct data_fields)) == 8);
+}
+
+namespace block_write {
+  constexpr uint32_t command_code = 0xc;
+  
+  template <int N>
+  struct data_fields {
+    uint8_t function_type[4];
+    uint8_t pt[1];
+    uint8_t phase[1];
+    uint8_t block_no[2];
+    uint8_t written_data[N];
+  };
+  
+  static_assert((sizeof (struct data_fields<0>)) == 8);
+}
+
+namespace get_last_error {
+  constexpr uint32_t command_code = 0xd;
+  
+  struct data_fields {
+    uint8_t function_type[4];
+    uint8_t pt[1];
+    uint8_t phase[1];
+    uint8_t block_no[2];
+  };
+  
+  static_assert((sizeof (struct data_fields)) == 8);
+}
+
+namespace set_condition {
+  constexpr uint32_t command_code = 0xe;
+  
+  template <int N>
+  struct data_fields {
+    uint8_t function_type[4];
+    uint8_t write_in_data[N];
+  };
+  
+  static_assert((sizeof (struct data_fields<0>)) == 4);
+}
+
+namespace ft4_control {
+  constexpr uint32_t command_code = 0xf;
+  
+  template <int N>
+  struct data_fields {
+    uint8_t function_type[4];
+    uint8_t ft4_data[N];
+  };
+  
+  static_assert((sizeof (struct data_fields<0>)) == 4);
+}
+
+namespace ar_control {
+  constexpr uint32_t command_code = 0x10;
+  
+  template <int N>
+  struct data_fields {
+    uint8_t function_type[4];
+    uint8_t data[N];
+  };
+  
+  static_assert((sizeof (struct data_fields<0>)) == 4);
+}
+
+namespace function_type_unknown {
+  constexpr uint32_t command_code = 0xfe;
+  
+  struct data_fields {
+  };
+}
+
+namespace command_unknown {
+  constexpr uint32_t command_code = 0xfd;
+  
+  struct data_fields {
+  };
+}
+
+namespace transmit_again {
+  constexpr uint32_t command_code = 0xfc;
+  
+  struct data_fields {
+  };
+}
+
+namespace file_error {
+  constexpr uint32_t command_code = 0xfb;
+  
+  struct data_fields {
+    uint8_t function_error_code[4];
+  };
+  
+  static_assert((sizeof (struct data_fields)) == 4);
+}
+
+namespace lcd_error {
+  constexpr uint32_t command_code = 0xfa;
+  
+  struct data_fields {
+    uint8_t function_error_code[4];
+  };
+  
+  static_assert((sizeof (struct data_fields)) == 4);
+}
+
+namespace ar_error {
+  constexpr uint32_t command_code = 0xf9;
+  
+  struct data_fields {
+    uint8_t function_error_code[4];
+  };
+  
+  static_assert((sizeof (struct data_fields)) == 4);
+}
+
diff --git a/maple_bus_commands.h b/maple_bus_commands.h
index fce4be1..18c41cc 100644
--- a/maple_bus_commands.h
+++ b/maple_bus_commands.h
@@ -5,24 +5,32 @@
 
 namespace device_request {
   constexpr uint32_t command_code = 0x1;
+  struct data_fields {
+  };
 }
 
 namespace all_status_request {
   constexpr uint32_t command_code = 0x2;
+  struct data_fields {
+  };
 }
 
 namespace device_reset {
   constexpr uint32_t command_code = 0x3;
+  struct data_fields {
+  };
 }
 
 namespace device_kill {
   constexpr uint32_t command_code = 0x4;
+  struct data_fields {
+  };
 }
 
 namespace device_status {
   constexpr uint32_t command_code = 0x5;
-  
   struct data_fields {
+
     uint8_t device_id[16];
     uint8_t destination_code[1];
     uint8_t connection_direction[1];
@@ -31,15 +39,15 @@ namespace device_status {
     uint8_t low_consumption_standby_current[2];
     uint8_t maximum_current_consumption[2];
   };
-  
+
   static_assert((sizeof (struct data_fields)) == 112);
 }
 
 namespace device_all_status {
   constexpr uint32_t command_code = 0x6;
-  
-  template <int N>
   struct data_fields {
+
+    template <int N>
     uint8_t device_id[16];
     uint8_t destination_code[1];
     uint8_t connection_direction[1];
@@ -49,162 +57,169 @@ namespace device_all_status {
     uint8_t maximum_current_consumption[2];
     uint8_t free_device_status[N];
   };
-  
+
   static_assert((sizeof (struct data_fields<0>)) == 112);
 }
 
 namespace device_reply {
   constexpr uint32_t command_code = 0x7;
+  struct data_fields {
+  };
 }
 
 namespace data_transfer {
   constexpr uint32_t command_code = 0x8;
-  
-  template <int N>
   struct data_fields {
+
+    template <int N>
     uint8_t data[N];
   };
-  
+
   static_assert((sizeof (struct data_fields<0>)) == 0);
 }
 
 namespace get_condition {
   constexpr uint32_t command_code = 0x9;
-  
   struct data_fields {
+
     uint8_t function_type[4];
   };
-  
+
   static_assert((sizeof (struct data_fields)) == 4);
 }
 
 namespace get_media_info {
   constexpr uint32_t command_code = 0xa;
-  
   struct data_fields {
+
     uint8_t function_type[4];
     uint8_t pt[4];
   };
-  
+
   static_assert((sizeof (struct data_fields)) == 8);
 }
 
 namespace block_read {
   constexpr uint32_t command_code = 0xb;
-  
   struct data_fields {
+
     uint8_t function_type[4];
     uint8_t pt[1];
     uint8_t phase[1];
     uint8_t block_no[2];
   };
-  
+
   static_assert((sizeof (struct data_fields)) == 8);
 }
 
 namespace block_write {
   constexpr uint32_t command_code = 0xc;
-  
-  template <int N>
   struct data_fields {
+
+    template <int N>
     uint8_t function_type[4];
     uint8_t pt[1];
     uint8_t phase[1];
     uint8_t block_no[2];
     uint8_t written_data[N];
   };
-  
+
   static_assert((sizeof (struct data_fields<0>)) == 8);
 }
 
 namespace get_last_error {
   constexpr uint32_t command_code = 0xd;
-  
   struct data_fields {
+
     uint8_t function_type[4];
     uint8_t pt[1];
     uint8_t phase[1];
     uint8_t block_no[2];
   };
-  
+
   static_assert((sizeof (struct data_fields)) == 8);
 }
 
 namespace set_condition {
   constexpr uint32_t command_code = 0xe;
-  
-  template <int N>
   struct data_fields {
+
+    template <int N>
     uint8_t function_type[4];
     uint8_t write_in_data[N];
   };
-  
+
   static_assert((sizeof (struct data_fields<0>)) == 4);
 }
 
 namespace ft4_control {
   constexpr uint32_t command_code = 0xf;
-  
-  template <int N>
   struct data_fields {
+
+    template <int N>
     uint8_t function_type[4];
     uint8_t ft4_data[N];
   };
-  
+
   static_assert((sizeof (struct data_fields<0>)) == 4);
 }
 
 namespace ar_control {
   constexpr uint32_t command_code = 0x10;
-  
-  template <int N>
   struct data_fields {
+
+    template <int N>
     uint8_t function_type[4];
     uint8_t data[N];
   };
-  
+
   static_assert((sizeof (struct data_fields<0>)) == 4);
 }
 
 namespace function_type_unknown {
   constexpr uint32_t command_code = 0xfe;
+  struct data_fields {
+  };
 }
 
 namespace command_unknown {
   constexpr uint32_t command_code = 0xfd;
+  struct data_fields {
+  };
 }
 
 namespace transmit_again {
   constexpr uint32_t command_code = 0xfc;
+  struct data_fields {
+  };
 }
 
 namespace file_error {
   constexpr uint32_t command_code = 0xfb;
-  
   struct data_fields {
+
     uint8_t function_error_code[4];
   };
-  
+
   static_assert((sizeof (struct data_fields)) == 4);
 }
 
 namespace lcd_error {
   constexpr uint32_t command_code = 0xfa;
-  
   struct data_fields {
+
     uint8_t function_error_code[4];
   };
-  
+
   static_assert((sizeof (struct data_fields)) == 4);
 }
 
 namespace ar_error {
   constexpr uint32_t command_code = 0xf9;
-  
   struct data_fields {
+
     uint8_t function_error_code[4];
   };
-  
+
   static_assert((sizeof (struct data_fields)) == 4);
 }
-
diff --git a/notes/hamming-framing.txt b/notes/hamming-framing.txt
new file mode 100644
index 0000000..84afa04
--- /dev/null
+++ b/notes/hamming-framing.txt
@@ -0,0 +1,11 @@
+frames:
+ 0b00 invalid
+ 0b01 command begin
+ 0b10 data begin
+ 0b11 frame end
+
+commands:
+ - jump addr
+ - read addr
+ - write addr
+ - speed value
diff --git a/maple-notes.txt b/notes/maple.txt
similarity index 100%
rename from maple-notes.txt
rename to notes/maple.txt
diff --git a/notes.txt b/notes/ta.txt
similarity index 100%
rename from notes.txt
rename to notes/ta.txt
diff --git a/vga-notes.txt b/notes/vga.txt
similarity index 100%
rename from vga-notes.txt
rename to notes/vga.txt
diff --git a/regs/gen/core_bits.py b/regs/gen/core_bits.py
index 9706524..4d06746 100644
--- a/regs/gen/core_bits.py
+++ b/regs/gen/core_bits.py
@@ -206,7 +206,7 @@ def render_registers(registers):
 def header():
     yield "#include <cstdint>"
     yield ""
-    yield '#include "float_uint32.h"'
+    yield '#include "../float_uint32.h"'
     yield ""
 
 if __name__ == "__main__":
diff --git a/regs/gen/maple_commands.py b/regs/gen/maple_commands.py
index d67595a..30dd322 100644
--- a/regs/gen/maple_commands.py
+++ b/regs/gen/maple_commands.py
@@ -3,7 +3,6 @@ from typing import Union
 import sys
 
 from sh7091 import read_input
-from sh7091 import headers
 from generate import renderer
 
 @dataclass
@@ -17,15 +16,15 @@ def command_namespace(namespace: CommandNamespace,
                       data_fields: list[tuple[str, tuple[int, str]]]):
     yield f"namespace {namespace.name} {{"
     yield f"constexpr uint32_t command_code = {hex(namespace.command_code)};"
+    yield ""
 
     if namespace.data_size == (0, None):
         assert data_fields == []
-        # do nothing
+        yield "struct data_fields {"
+        yield "};"
     else:
         length, variable = namespace.data_size
 
-        yield ""
-
         if variable is not None:
             assert variable.lower() == "n"
             yield "template <int N>"
@@ -149,6 +148,10 @@ def new_aggregator():
 
     return process
 
+def headers():
+    yield "#include <cstdint>"
+    yield ""
+
 input_file = sys.argv[1]
 rows = read_input(input_file)
 process = new_aggregator()