Game Identification

This page details the hashing method used for each supported system. First, systems where the entire game file is hashed are listed, and later systems where the RA hash may differ from the file MD5.

Systems that Hash the Entire File

Apple II

NOTE: As saving and other manipulations can mutate disk data, local copies of loaded images are required to ensure that their hashes do not change across sessions.

Atari 2600

Atari Jaguar

ColecoVision

Fairchild Channel F

Game Boy

Game Boy Color

Game Boy Advance

Game Gear

Intellivision

MSX / MSX 2

NOTE: As saving mutates disk data, local copies of loaded images are required to ensure that their hashes do not change across sessions. We do not believe this is working, but have yet to find a game where saving to disk actually works.

Magnavox Odyssey 2

Mega Duck

Neo Geo Pocket

Neo Geo Pocket Color

PC-8001 / PC-8801

NOTE: As saving and other manipulations can mutate disk data, local copies of loaded images are required to ensure that their hashes do not change across sessions.

Pokemon Mini

Sega 32X

Sega Master System

Sega Mega Drive / Genesis

Sega SG-1000

TIC-80

Vectrex

VirtualBoy

Watara Supervision

WonderSwan

WonderSwan Color

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Systems that Hash a Portion of the File

3DO

The volume header (first 132 bytes of sector 0) and the contents of the LaunchMe file are hashed.

Arcade

The filename string without the extension (path/galaga.zip -> galaga) is hashed. It is case-sensitive.

Atari 7800

If the ROM starts with \1ATARI7800, the first 128 bytes are ignored and the remaining file contents are hashed. If the ROM does not start with \1ATARI7800, the entire file is hashed.

Atari Lynx

If the ROM starts with LYNX\0, the first 64 bytes are ignored and the remaining file contents are hashed. If the ROM does not start with LYNX\0, the entire file is hashed.

Famicom Disk System

If the ROM starts with FDS\1a, the first 16 bytes are ignored and the remaining file contents are hashed. If the ROM does not start with FDS\1a, the entire file is hashed. NOTE: As saving mutates disk data, local copies of loaded images are required to ensure that their hashes do not change across sessions.

Nintendo DS

An NDS ROM has a 0x160 byte header. In this header are pointers to icon/title information and to the boot code for both processors. The hash method combines the header, the two pieces of boot code, and the icon/title information and hashes the result.

• The icon/title information is 0xA00 bytes starting at the address stored in the header at $68
• The arm9 code address is stored at $20 in the header, and the size is stored at $2C in the header
• The arm7 code address is stored at $30 in the header, and the size is stored at $3C in the header

Nintendo Entertainment System

If the ROM starts with NES\1a, the first 16 bytes are ignored and the remaining file contents are hashed. If the ROM does not start with NES\1a, the entire file is hashed.

PC Engine / TurboGrafx-16

If the size of the file is 512 bytes more than a multiple of 128KB, the first 512 bytes are ignored and the remaining file contents are hashed. If the size of the file is not 512 bytes more than a multiple of 128KB, the entire file is hashed.

PC Engine CD / TurboGrafx-CD

The boot code and disc title are hashed as follows:

• Read 128 bytes from sector 1 of the data track (PCE predates ISO-9660, so there's no file system to read).
• If "PC Engine CD-ROM SYSTEM" does not exist at 32 bytes into the data, discard as invalid.
• Copy the last 22 bytes of the data into a buffer. This is the disc title, and usually identifies the game.
• The first three bytes of the data are a little-endian sector index for the boot code.
• The fourth byte is the number of sectors that the boot code occupies.
• The boot code is appended to the buffer (N sectors, starting at sector X)
• The buffer is hashed.

PC-FX

The boot code and disc title are hashed as follows:

• Read 32 bytes from sector 0 of the data track (PC-FX predates ISO-9660, so there's no file system to read).
• If "PC-FX:Hu_CD-ROM" was not read, discard as invalid.
• Read 128 bytes from sector 1 of the data track into a buffer. This is the volume header and includes the disc title.
• The 32-bit value at 32-bytes into the buffer is the first sector of the boot code.
• The 32-bit value at 36-bytes into the buffer is the number of sectors that the boot code occupies.
• The boot code is appended to the buffer (N sectors, starting at sector X)
• The buffer is hashed.

PlayStation

The primary executable and its name are hashed as follows:

• The SYSTEM.CNF file is loaded and parsed. The primary executable is identified by the BOOT= line within.
• The primary executable name (and its path) are extracted from SYSTEM.CNF and written to a buffer.
• The contents of the primary executable are appended to the buffer.
• The buffer is hashed.

PlayStation 2

The primary executable and its name are hashed as follows:

• The SYSTEM.CNF file is loaded and parsed. The primary executable is identified by the BOOT2= line within.
• The primary executable name (and its path) are extracted from SYSTEM.CNF and written to a buffer.
• The contents of the primary executable are appended to the buffer.
• The buffer is hashed.

PlayStation Portable

The disc metadata and primary executable are hashed as follows:

• The contents of the PSP_GAME\PARAMS.SFO file are written to a buffer. This contains the game attributes displayed in the menu, including the name and serial.
• The contents of the primary executable (PSP_GAME\SYSDIR\EBOOT.BIN) are appended to the buffer.
• The buffer is hashed.

Sega CD / Sega Saturn

• The first 512 bytes of sector 0 are hashed. This contains the volume header and ROM header. The first 16 bytes must be "SEGADISCSYSTEM " for Sega CD or "SEGA SEGASATURN " for Sega Saturn. If not, discard as invalid.
• Immediately following those 512 bytes are an arbitrary amount of code that validates the region and loads the primary executable. Without processing the code, we cannot determine what additional file(s) to hash, so this was determined to be sufficient as an alternative to hashing the entire CD.

Sega Dreamcast

The disc metadata and primary executable are hashed as follows:

• The first 512 bytes of sector 0 are appended to the buffer. This contains the volume header and ROM header. The first 16 bytes must be "SEGA SEGAKATANA ". If not, discard as invalid.
• The contents of the primary executable (as identified by the volume header) are appended to the buffer.
• The buffer is hashed.

SNES

If the size of the file is 512 bytes more than a multiple of 8KB, the first 512 bytes are ignored and the remaining file contents are hashed. If the size of the file is not 512 bytes more than a multiple of 8KB, the entire file is hashed.

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Pending Explanation

Amstrad CPC

Arduboy

Atari Jaguar CD

Game Cube

Neo Geo CD

Wii