diff --git a/maple_bus_commands.h b/maple_bus_commands.h
new file mode 100644
index 0000000..fce4be1
--- /dev/null
+++ b/maple_bus_commands.h
@@ -0,0 +1,210 @@
+#include <stdint.h>
+#include <stddef.h>
+
+#include "type.h"
+
+namespace device_request {
+  constexpr uint32_t command_code = 0x1;
+}
+
+namespace all_status_request {
+  constexpr uint32_t command_code = 0x2;
+}
+
+namespace device_reset {
+  constexpr uint32_t command_code = 0x3;
+}
+
+namespace device_kill {
+  constexpr uint32_t command_code = 0x4;
+}
+
+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;
+}
+
+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;
+}
+
+namespace command_unknown {
+  constexpr uint32_t command_code = 0xfd;
+}
+
+namespace transmit_again {
+  constexpr uint32_t command_code = 0xfc;
+}
+
+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/regs/gen/maple_commands.py b/regs/gen/maple_commands.py
new file mode 100644
index 0000000..d67595a
--- /dev/null
+++ b/regs/gen/maple_commands.py
@@ -0,0 +1,160 @@
+from dataclasses import dataclass
+from typing import Union
+import sys
+
+from sh7091 import read_input
+from sh7091 import headers
+from generate import renderer
+
+@dataclass
+class CommandNamespace:
+    name: str
+    issuing_right: set[str]
+    command_code: int
+    data_size: int
+
+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)};"
+
+    if namespace.data_size == (0, None):
+        assert data_fields == []
+        # do nothing
+    else:
+        length, variable = namespace.data_size
+
+        yield ""
+
+        if variable is not None:
+            assert variable.lower() == "n"
+            yield "template <int N>"
+
+        yield "struct data_fields {"
+
+        for field_name, field_size in data_fields:
+            const, var = field_size
+            if var is None:
+                yield f"uint8_t {field_name}[{const}];"
+            elif const == 0:
+                assert var == "n"
+                yield f"uint8_t {field_name}[{var.upper()}];"
+            else:
+                yield f"uint8_t {field_name}[{const} + {var.upper()}];"
+
+        yield "};"
+
+        yield ""
+
+        if variable is not None:
+            assert variable == "n"
+            yield f"static_assert((sizeof (struct data_fields<0>)) == {length});"
+        else:
+            yield f"static_assert((sizeof (struct data_fields)) == {length});"
+
+    yield "}"
+    yield ""
+
+def parse_data_size(data_size, base, multiple) -> tuple[int, str]:
+    def parse_term(s):
+        try:
+            return int(s, base) * multiple
+        except ValueError:
+            div = s.split("/")
+            if len(div) == 1:
+                # this must be a variable
+                assert multiple == 1, s
+                a, = div
+                return a
+            elif len(div) == 2:
+                # this must be a variable divided by a number
+                a, b = div
+                b = int(b, 10)
+                assert b == multiple
+                return a
+            else:
+                assert False, div
+
+    _terms = data_size.split("+")
+    terms = tuple(parse_term(term) for term in _terms)
+    if len(terms) == 1:
+        term, = terms
+        if type(term) == str:
+            return (0, term)
+        elif type(term) == int:
+            return (term, None)
+        else:
+            assert False, (_terms, terms)
+    elif len(terms) == 2:
+        assert type(terms[0]) == int
+        assert type(terms[1]) == str
+        return terms
+    else:
+        assert False, (_terms, terms)
+
+def new_aggregator():
+    last_name = None
+    namespace = None
+    data_fields = []
+    all_names = set()
+
+    def process_row(row):
+        nonlocal last_name
+        nonlocal namespace
+        nonlocal data_fields
+
+        if row["name"] == "":
+            assert all(v == "" for v in row.values()), row
+            return
+
+        if row["name"] != last_name:
+            if namespace is not None:
+                yield namespace, data_fields
+            else:
+                assert data_fields == []
+            assert row["name"] != ""
+            last_name = row["name"]
+            issuing_right = set(row["issuing_right"].split(", "))
+            assert all(s in {"host", "peripheral"} for s in issuing_right), row
+            assert issuing_right != set(), issuing_right
+            data_size = parse_data_size(row["data_size"], 16, 4)
+
+            namespace = CommandNamespace(
+                name = row["name"],
+                issuing_right = issuing_right,
+                command_code = int(row["command_code"], 16),
+                data_size = data_size,
+            )
+            data_fields = []
+            # fall through
+
+        assert last_name is None or row["name"] == last_name, (row["name"], last_name)
+        if row["data_field"] != "":
+            assert row["data_field_size"] != ""
+            data_fields.append((
+                row["data_field"],
+                parse_data_size(row["data_field_size"], 10, 1)
+            ))
+
+    def terminate():
+        nonlocal namespace
+        nonlocal data_fields
+        if namespace is not None:
+            yield namespace, data_fields
+
+    def process(rows):
+        for row in rows:
+            yield from process_row(row)
+        yield from terminate()
+
+    return process
+
+input_file = sys.argv[1]
+rows = read_input(input_file)
+process = new_aggregator()
+
+render, out = renderer()
+render(headers())
+for namespace, data_fields in process(rows):
+    render(command_namespace(namespace, data_fields))
+sys.stdout.write(out.getvalue())
diff --git a/regs/maple_bus_commands.csv b/regs/maple_bus_commands.csv
new file mode 100644
index 0000000..e3700de
--- /dev/null
+++ b/regs/maple_bus_commands.csv
@@ -0,0 +1,71 @@
+"name","issuing_right","command_code","data_size","data_field","data_field_size"
+"device_request","host","0x01","0x00",,
+,,,,,
+"all_status_request","host","0x02","0x00",,
+,,,,,
+"device_reset","host","0x03","0x00",,
+,,,,,
+"device_kill","host","0x04","0x00",,
+,,,,,
+"device_status","peripheral","0x05","0x1c","device_id",16
+"device_status",,,,"destination_code",1
+"device_status",,,,"connection_direction",1
+"device_status",,,,"product_name",30
+"device_status",,,,"license",60
+"device_status",,,,"low_consumption_standby_current",2
+"device_status",,,,"maximum_current_consumption",2
+,,,,,
+"device_all_status","peripheral","0x06","0x1c+n/4","device_id",16
+"device_all_status",,,,"destination_code",1
+"device_all_status",,,,"connection_direction",1
+"device_all_status",,,,"product_name",30
+"device_all_status",,,,"license",60
+"device_all_status",,,,"low_consumption_standby_current",2
+"device_all_status",,,,"maximum_current_consumption",2
+"device_all_status",,,,"free_device_status","n"
+,,,,,
+"device_reply","peripheral","0x07","0x00",,
+,,,,,
+"data_transfer","peripheral","0x08","n/4","data","n"
+,,,,,
+"get_condition","host","0x09","0x01","function_type",4
+,,,,,
+"get_media_info","host","0x0a","0x02","function_type",4
+"get_media_info",,,,"pt",4
+,,,,,
+"block_read","host","0x0b","0x02","function_type",4
+"block_read",,,,"pt",1
+"block_read",,,,"phase",1
+"block_read",,,,"block_no",2
+,,,,,
+"block_write","host","0x0c","0x02+n/4","function_type",4
+"block_write",,,,"pt",1
+"block_write",,,,"phase",1
+"block_write",,,,"block_no",2
+"block_write",,,,"written_data","n"
+,,,,,
+"get_last_error","host","0x0d","0x02","function_type",4
+"get_last_error",,,,"pt",1
+"get_last_error",,,,"phase",1
+"get_last_error",,,,"block_no",2
+,,,,,
+"set_condition","host","0x0e","0x01+n/4","function_type",4
+"set_condition",,,,"write_in_data","n"
+,,,,,
+"ft4_control","host","0x0f","0x01+n/4","function_type",4
+"ft4_control",,,,"ft4_data","n"
+,,,,,
+"ar_control","host","0x10","0x01+n/4","function_type",4
+"ar_control",,,,"data","n"
+,,,,,
+"function_type_unknown","peripheral","0xfe","0x00",,
+,,,,,
+"command_unknown","peripheral","0xfd","0x00",,
+,,,,,
+"transmit_again","host, peripheral","0xfc","0x00",,
+,,,,,
+"file_error","peripheral","0xfb","0x01","function_error_code",4
+,,,,,
+"lcd_error","peripheral","0xfa","0x01","function_error_code",4
+,,,,,
+"ar_error","peripheral","0xf9","0x01","function_error_code",4
diff --git a/regs/maple_bus_commands.ods b/regs/maple_bus_commands.ods
new file mode 100644
index 0000000..abd09bd
Binary files /dev/null and b/regs/maple_bus_commands.ods differ
diff --git a/regs/maple_bus_ft0.ods b/regs/maple_bus_ft0.ods
new file mode 100644
index 0000000..55a72af
Binary files /dev/null and b/regs/maple_bus_ft0.ods differ
diff --git a/regs/maple_bus_ft6.ods b/regs/maple_bus_ft6.ods
new file mode 100644
index 0000000..c4c51d5
Binary files /dev/null and b/regs/maple_bus_ft6.ods differ
diff --git a/regs/maple_bus_ft6_key_mapping.ods b/regs/maple_bus_ft6_key_mapping.ods
new file mode 100644
index 0000000..453bee3
Binary files /dev/null and b/regs/maple_bus_ft6_key_mapping.ods differ