Save data structure (Generation II)
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This article is incomplete. Please feel free to edit this article to add missing information and complete it. |
Overview
The save data structure for Generation II is stored in the cartridge's battery-backed RAM chip (SRAM), or as a ".sav" file from most emulators. The structure consists of 32 KB of data, though not every byte is used. Emulators may append additional data for the purposes of maintaining real-time clock operations.
Two regions of the save data have their integrity validated via checksums. These region contain all of the information that directly pertains to the player and his or her Pokémon. Additional information pertinent to the save file is also present in the other regions of the data.
Data Types
Unless otherwise noted, integer values occupy the specified number of bytes, and are big-endian and either unsigned or two's complement.
Text Data
Text data for Generation II is stored in a proprietary character set. The text characters available for use by players in the game have the following byte values:
-0 -1 -2 -3 -4 -5 -6 -7 -8 -9 -A -B -C -D -E -F 0-
1-
2-
3-
4-
5-
6-
7-Unused, except for:
0x50 (terminator) and
0x7F (space)8- A B C D E F G H I J K L M N O P 9- Q R S T U V W X Y Z ( ) : ; [ ] A- a b c d e f g h i j k l m n o p B- q r s t u v w x y z C-
D-Unused E- PK MN - ? ! . F- × / , 0 1 2 3 4 5 6 7 8 9
Notes
- Strings of text are terminated with 0x50, rather than the traditional 0x00. A terminator must be present at the end of every string of text.
- If a string is shorter than the maximum number of characters allocated for it, then the remaining bytes after the terminator are padded with junk.
Item Lists
Lists of items in the save data follow a particular format.
Lists have entries of 2 bytes each, and a capacity. The total size of the list data, in bytes, is:
Capacity * 2 + 2
For example, your pocket inventory can hold 20 item entries, so the size of that list is 20 * 2 + 2 = 42 bytes.
| Offset | Size | Contents |
|---|---|---|
| 0x00 | 1 | Count |
| 0x01 | 2 * Capacity | Entries |
| ... +0x00 | 1 | Terminator |
Count
The number of item entries actually being represented in the list.
Entries
The exact data for each item entry in the list. For more information, see below.
Terminator
The byte following the last item entry, according to Count, must always be a terminator, which is byte value 0xFF.
This spare byte is present at the end of the list data for the event when the list is filled to capacity.
Entry Format
The Entry record has the following format:
| Offset | Size | Contents |
|---|---|---|
| 0x00 | 1 | Count |
| 0x01 | 1 | Index |
Count
The number of that particular item. Must be 1 to 99, inclusive.
Index
The item's index.
Pokémon Lists
Lists of Pokémon in the save data follow a particular format.
Lists have entries of varying sizes, and a capacity. The total size of the list data, in bytes, is:
Capacity * (Size + 23) + 2
For example, your Pokémon team contains 6 entries and each entry is 48 bytes in size, so the size of that list is 6 * (48 + 23) + 2 = 428 bytes.
| Offset | Size | Contents |
|---|---|---|
| 0x0000 | 1 | Count |
| 0x0001 | Capacity + 1 | Species |
| ... + 0x0000 | Capacity * Size | Pokémon |
| ... + 0x0000 | Capacity * 11 | OT Names |
| ... + 0x0000 | Capacity * 11 | Names |
Count
The number of Pokémon entries actually being represented in the list.
Species
A list of species indexes, one for each Pokémon in the list. This is used by the team menu as well as the PC management interface.
The byte following the last species entry, according to Count, must always be a terminator, which is byte value 0xFF.
If an entry in this field is set to 0xFD, then the corresponding Pokémon is still in its egg.
Pokémon
The exact data for each Pokémon entry in the list. For the format, please refer to: Pokémon data structure in Generation II
- For team Pokémon, the entry size is the full 48 bytes as documented in that article.
- For PC Pokémon, only the first 32 bytes are used, meaning everything after Level is not included. Instead, those values are regenerated upon withdrawing a Pokémon from the PC. This is the basis of the Box trick.
OT Names
Text strings representing the names of the original trainers for each Pokémon entry. Each name can contain from 1 to 10 characters.
Names
Text strings representing the names for each Pokémon entry. Each name can contain from 1 to 10 characters.
A name is considered a "nickname" if it does not perfectly match the default name for a Pokémon. The default name follows these rules:
- The first however many characters must match the species name exactly. This is typically all-uppercase.
- The remainder of the string must be all terminator characters, aka
0x50.
Therefore, if a Pokémon with a 9- or 10-letter species name, such as Charmander, is given a nickname that matches the species name, the nickname will not be retained should that Pokémon evolve.
File Structure
Known data within the save file can be found at the following offsets within the data, such that offset 0 is the first byte of the emulator ".sav" file.
Although all data appears twice in the save file, only the primary copy is documented below. For more information, see the Checksums section.
Editor's Note: This applies to the English Gold, Silver and Crystal for sure, but whether any of it is different in Japanese and/or other languages is yet to be seen.
| OffsetGS | OffsetC | Size | Contents |
|---|---|---|---|
| 0x2009 | 0x2009 | 2 | Player Trainer ID |
| 0x200B | 0x200B | 8 | Trainer Name |
| 0x2021 | 0x2021 | 8 | Rival Name |
| 0x2050 | 0x2050 | 1 | Daylight Savings |
| 0x2053 | 0x2054 | 4 | Time Played |
| 0x206B | 0x206A | 1 | Player Palette |
| 0x23DB | 0x23DB | 3 | Money |
| 0x23E6 | 0x23E7 | 57 | TM Pocket |
| 0x241F | 0x2420 | 42 | Item Pocket Item List |
| 0x2449 | 0x244A | 54 | Key Item Pocket Item List |
| 0x2464 | 0x2465 | 26 | Ball Pocket Item List |
| 0x247E | 0x247F | 102 | PC Item List |
| 0x2724 | 0x2700 | 1 | Current PC Box |
| 0x288A | 0x2865 | 404 | Team Pokémon List |
| 0x2A4C | 0x2A27 | 32 | Pokédex Owned |
| 0x2A6C | 0x2A47 | 32 | Pokédex Seen |
| 0x2D6C | 0x2D11 | 1102 | Current Box Pokémon List |
| N/A | 0x3E3D | 1 | Player Gender |
| 0x4000 | 0x4000 | 1102 | PC Box 1 Pokémon List |
| 0x4450 | 0x4450 | 1102 | PC Box 2 Pokémon List |
| 0x48A0 | 0x48A0 | 1102 | PC Box 3 Pokémon List |
| 0x4CF0 | 0x4CF0 | 1102 | PC Box 4 Pokémon List |
| 0x5140 | 0x5140 | 1102 | PC Box 5 Pokémon List |
| 0x5590 | 0x5590 | 1102 | PC Box 6 Pokémon List |
| 0x59E0 | 0x59E0 | 1102 | PC Box 7 Pokémon List |
| 0x6000 | 0x6000 | 1102 | PC Box 8 Pokémon List |
| 0x6450 | 0x6450 | 1102 | PC Box 9 Pokémon List |
| 0x68A0 | 0x68A0 | 1102 | PC Box 10 Pokémon List |
| 0x6CF0 | 0x6CF0 | 1102 | PC Box 11 Pokémon List |
| 0x7140 | 0x7140 | 1102 | PC Box 12 Pokémon List |
| 0x7590 | 0x7590 | 1102 | PC Box 13 Pokémon List |
| 0x79E0 | 0x79E0 | 1102 | PC Box 14 Pokémon List |
| 0x2D69 | 0x2D02 | 2 | Checksum 1 |
| 0x7E6D | 0x1F0D | 2 | Checksum 2 |
Trainer Name, Rival Name
Represents text strings that can be from 1 to 7 characters in length.
Daylight Savings
Specifies whether Daylight Savings (DST) is in effect.
The highest bit of this field is set to indicate DST is in effect.
The lower 7 bits of this field have unknown significance.
Time Played
Specifies how much time has elapsed during gameplay.
This value is actually 4 1-byte values representing, in this order: the hours, minutes, seconds and "frames" that have elapsed. A frame is 1/60th of a second.
This timer is not halted when the game is paused, and also counts up on the main menu before selecting to continue a saved game.
Player Palette
Specifies the colors of the player character.
From a technical standpoint, the lowest 3 bits of this field are transferred to OAM to select the colors when drawing the player character.
From a practical standpoint, this value is set by the game depending on whether the player character is a boy or a girl:
- For boy characters, this is set to
0x00(red) - For girl characters, this is set to
0x01(purple)
Despite only being able to make boy characters in Gold and Silver, this field is still present and functional.
TM Pocket
The items that the player has in his or her TM Pocket inventory.
| Offset | Size | Contents |
|---|---|---|
| 0x00 | 50 | TMs List |
| 0x32 | 7 | HMs List |
TMs List
Each byte specifies the quantity of the corresponding TM that the player is holding. Should be 0 to 99.
Indexes match item numbers, meaning 0 corresponds with TM01 and 49 corresponds with TM50.
HMs List
Each byte specifies the quantity of the corresponding HM that the player is holding. Should be 0 to 1.
Indexes match item numbers, meaning 0 corresponds with HM01 and 6 corresponds with HM07.
Item Pocket Item List
The items that the player has in his or her Item Pocket inventory.
Stored as an Item List with a capacity of 20.
Key Item Pocket Item List
The items that the player has in his or her Key Item Pocket inventory.
Stored as an Item List with a capacity of 26.
Ball Pocket Item List
The items that the player has in his or her Ball Pocket inventory.
Stored as an Item List with a capacity of 12.
PC Item List
The items that the player has stored in the PC.
Stored as an Item List with a capacity of 50.
Current PC Box
Indicates which PC box is currently selected, minus 1. That is to say, box 1 is represented as 0, and box 14 is represented as 13.
The lowest 4 bits of this value are the box index.
Team Pokémon List
The Pokémon that the player has in his or her team.
Stored as a Pokemon List with a capacity of 6 and an entry size of 48 bytes.
Pokédex Owned, Pokédex Seen
Represents the specific Pokédex entries that have been either seen or owned during gameplay.
Pokémon are indexed by their usual Pokédex order, meaning the order is the same as in the National Pokédex. However, indexes begin counting at 0, rather than 1.
1 bit is used to represent whether a given Pokémon has been seen/owned. Bits are ordered within bytes from lowest to highest, starting with the first byte. Therefore, the exact bit can be extracted from the list using the following formula:
Bit = ( Data[ RoundDown(PokeNum / 8) ] / 2 ^ (PokeNum Mod 8) ) AND 1
Or in C-style code (shift occurs before other bitwise operations):
Bit = Data[PokeNum >> 3] >> (PokeNum & 7) & 1;
Example
Let us say that we want to know whether #120 Staryu has been seen/owned:
- PokeNum becomes 119, since it is 0-based.
- The byte of the list in which bit 119 is located is = 119 / 8 = 14
- The bit within that byte is = 119 Mod 8 = 7
- Dividing the byte value by 2 ^ Bit, or shifting right by Bit, moves the bit to the least-significant position
- Performing a bitwise AND with 1 will remove all but the least-significant bit
PC Box Pokémon Lists
The Pokémon that the player has stored in PC boxes.
Stored as Pokemon Lists with a capacity of 20 and an entry size of 33 bytes.
Normally, Pokémon are deposited and withdrawn from the Current Box list, which is within the checksum-validated region of the save data. When switching boxes, the data from the Current Box is copied to the corresponding PC Box data, then the data from the switched-to PC Box is transferred into the Current Box data.
Player Gender
Specifies the gender of the player character:
- For boy characters, this is set to
0x00 - For girl characters, this is set to
0x01
Checksums
Used to validate the integrity of saved data.
Player data in Generation II is stored in the save file twice. The primary copy is located at 0x2009, and a secondary copy is stored elsewhere in the file. Checksums are performed on both copies and stored in the data.
- If only one checksum is correct, then the information from that copy of the data will be used.
- If both values are incorrect, the player will be forced to start a new game.
The checksums are simply the 16-bit sum of all byte values of the corresponding byte regions. Checksums are stored as little-endian.
Gold and Silver
The secondary data copy in Gold and Silver is not contiguous like the primary copy is. Instead, it is split across 5 sections and stored at different locations in the save file. The following table shows which sections of the primary copy are relocated for the secondary copy:
| Primary | Secondary |
|---|---|
| 0x2009 to 0x222E | 0x15C7 to 0x17EC |
| 0x222F to 0x23D8 | 0x3D96 to 0x3F3F |
| 0x23D9 to 0x2855 | 0x0C6B to 0x10E7 |
| 0x2856 to 0x2889 | 0x7E39 to 0x7E6C |
| 0x288A to 0x2D68 | 0x10E8 to 0x15C6 |
Calculating the checksums, therefore, can be done as follows:
- Sum the bytes from 0x2009 to 0x2D68 and store the result at 0x2D69
- Sum the bytes from 0x0C6B to 0x17EC, 0x3D96 to 0x3F3F and 0x7E39 to 7E6C, and store the result at 0x7E6D
Crystal
The secondary data copy in Crystal is a byte-for-byte match of the primary copy is. The following table shows which sections of the save file are occupied by each copy:
| Primary | Secondary |
|---|---|
| 0x2009 to 0x2B82 | 0x1209 to 0x1D82 |
Calculating the checksums, therefore, can be done as follows:
- Sum the bytes from 0x2009 to 0x2B82 and store the result at 0x2D0D
- Sum the bytes from 0x1209 to 0x1D82 and store the result at 0x1F0D
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This data structure article is part of Project Games, a Bulbapedia project that aims to write comprehensive articles on the Pokémon games. |