iNES - RetroBIOS¶
Technical notes
NES and Famicom emulator by Marat Fayzullin, covering cartridges, the Famicom Disk System and the VS System. The build read here is the free Android APK the author publishes himself, package com.fms.ines versionName 6.1.4 versionCode 6104, apk md5 d0e1b93b09d4b58294efd4e1509e25ca, signed CN=Marat Fayzullin O=Garage Research issued 2011, sha256 d09469e9b550cbc9005d3bd089f3df5f0ba89cba71cdd3b33736a0382d6f9848; the two download paths on that site serve the same bytes. Google Play carries the emulator as com.fms.ines.free, the package ES-DE launches, and inside VGBAnext as com.fms.ng, the author recording that Play removed the original com.fms.ines listing over its built-in cheats. The native libraries keep their symbol tables, so the readings below cite libmain.so offsets in the x86_64 slice; the arm64-v8a, armeabi-v7a, armeabi and x86 slices carry the same filename set. The free iNES 6.1 builds for Windows and Ubuntu were read beside it and open the same files under the same names. No source has ever been published: the author releases ColEm and fMSX as source archives, while every iNES download on the same site, from 0.7 for AIX and SunOS through 6.1, is a binary package. ref: iNES-Android-6104.apk META-INF/CERT.RSA, https://fms.komkon.org/iNES/, iNES61-Windows-bin.zip, iNES61-Ubuntu-x86-bin.tgz
One directory holds everything the emulator reads. MainActivity hands
EMULib.k() to jniStart, which copies it into the buffer GetHomeDir returns and
passes that same buffer to SetPrivateDir. Every open goes through mopen, which
calls OpenRealFile: the name is tried as given and again as
DISKSYS.ROM is the only filename compiled into the emulator. LoadFDS reads the disk image first, taking a bare NINTENDO-HVC header or the 16 byte FDS wrapper ahead of it, then opens DISKSYS.ROM and reads 0x2000 bytes into RAM at 0xE000. A failed open leaves the status at NOT FOUND and a short read at FAILED, and either makes LoadFDS return zero, so the disk never starts. Nothing about the image is checked past the length of that read. Cartridge titles never reach this path. ref: libmain.so LoadFDS 0x3bdd0-0x3c245, open 0x3bf97, read 0x3bfc5-0x3bff7, iNES61-Ubuntu-x86-bin ines 0x38165-0x381a9
The startup palette is
LoadNES derives five companion names from the ROM path through MakeFileName: .sav, .ips, .cht, .pal and .sta. Started with no ROM name at all, Application substitutes CART.NES. ref: libmain.so LoadNES 0x3bb49, 0x3bc43, 0x3bcdc, 0x3bd2b, 0x3bd52, libmain.so Application 0x39887-0x3989c
Three package resources are read at runtime. assets/memfs.mp3 is passed whole to
jniStart and mounted as an in-memory filesystem carrying one entry, CART.NES.
assets/names.dat fills the title lookup and is then extended by
8 files | 1 required, 7 optional | 4 in repo, 4 missing Categories: 2 BIOS, 6 game data
DISKSYS.ROM required in repo
Famicom Disk System BIOS
- System: nintendo-fds
- Size: min 8.0 KB
- Validation: size
- Source:
libmain.so LoadFDS 0x3bdd0-0x3c245,iNES61-Ubuntu-x86-bin ines 0x38165-0x381a9 - Opened by bare name, so it resolves against the working directory and then against the home directory. Read as 0x2000 bytes into RAM at 0xE000; a missing file reports NOT FOUND and a short read FAILED, and either aborts the disk load. Only the length of that read is checked, so a longer file passes on its first 8192 bytes and no hash is compared. The open is gzip transparent, so a compressed copy answers too.
iNES.pal optional missing
startup colour palette
- System: nintendo-nes
- Source:
libmain.so Application 0x39739-0x39795,StartNES 0x3a685-0x3a694,LoadPAL 0x3a870-0x3a930 - Built as
/iNES.pal and loaded at startup when present, otherwise the built-in palette stands. Exactly 192 bytes is read as 64 RGB triples, any other length as text. No single file answers to this name: the desktop distribution ships twenty palettes under other names for the user to copy over.
CART.NES optional in repo game_data bundled
sample ROM image started when no game is given
- System: nintendo-nes
- Size: 24.0 KB
- SHA1:
486eede1bb74... - MD5:
c1db31a2aa8a... - CRC32:
2e03cb7f - Source:
MainActivity.java:2246-2257,libmain.so 0x11ca6-0x11ccc,libmain.so Application 0x39887-0x3989c - The only entry in assets/memfs.mp3, which MainActivity reads whole and jniStart mounts as an in-memory filesystem. A 16 byte header plus one 16 KB PRG bank and one 8 KB CHR bank. Application passes this name to StartNES when it is invoked without a ROM, so launching through ES-DE never reaches it.
names.dat optional in repo game_data bundled
title database keyed by system and CRC32
- Size: 20.9 KB
- Source:
FileInfo.java:260-295 - Parsed from assets as lines of key colon title, keys reading NES-4C629A95. The copy at
/names.dat is read straight afterwards into the same map, so user entries extend and override the packaged ones.
ROOT.chts optional in repo game_data bundled
cheat database read by the Cheatopedia browser
- Size: 26.8 KB
- Source:
Cheatopedia.java:339,Cheatopedia.java:448,Cheatopedia.java:505-520,CheatHelper.java:14-24 - Looked up in the package assets first, then through the home directory, its subdirectories and Downloads, with
/Cheats as the default cheat directory. Include lines pull further sets through the same lookup; the package carries seven of them, battle-toads, dragon-warrior, dragon-warrior-2, fceu, final-fantasy-2, final-fantasy-3 and super-mario-brothers.
<game>.ips optional missing game_data
IPS patch applied to the loaded ROM
- Source:
libmain.so LoadNES 0x3bc43,LoadFile 0x3acf8 - Named from the ROM path by MakeFileName and applied by ApplyIPS when present. A patch chosen by hand goes through the same call in LoadFile.
<game>.cht optional missing game_data
cheat codes for one title
- Source:
libmain.so LoadNES 0x3bcdc,Joystick 0x39e7f - Named from the ROM path by MakeFileName and read by LoadCHT when present. Distinct from the .chts sets of the Cheatopedia browser. The menu handler reaches the same loader for a file picked by hand.
<game>.pal optional missing game_data
colour palette for one title
- Source:
libmain.so LoadNES 0x3bd2b - Named from the ROM path by MakeFileName and read by LoadPAL when present, taking precedence over the startup palette for that game.
Generated on 2026-08-23T16:12:06Z