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PCSX2 Legacy - RetroBIOS
Type standalone
Classification Frozen snapshots
Source https://github.com/PCSX2/pcsx2
Version 1.6.0
Profiled 2026-08-08
Cores pcsx2-legacy, PCSX2-LEGACY
Systems sony-playstation-2
Technical notes

wxWidgets line, frozen at 1.6.0. Emulation is split across separate plugin binaries loaded at runtime: GSdx, Spu2-X, LilyPad, cdvdGigaherz, DEV9ghzdrk, USBnull and FWnull. Default BIOS folder is bios/ under the user documents directory. ref: pcsx2/gui/AppConfig.cpp:76-80, pcsx2/gui/AppConfig.cpp:192-195

BIOS selection lists every file in the folder with a . mask and keeps the ones whose romdir carries a RESET entry followed by a readable ROMVER, which supplies the version, the zone letter and the build date. Neither size nor hash is checked; the length test that would reject small images is commented out. A missing or zero-length image raises BiosLoadFailed. ref: pcsx2/gui/Panels/BiosSelectorPanel.cpp:151-177, pcsx2/ps2/BiosTools.cpp:74-167, pcsx2/ps2/BiosTools.cpp:325-341, pcsx2/ps2/BiosTools.cpp:261-323

The three companion ROMs derive from the selected BIOS path. Each extension is first appended to the full name, then substituted for the existing one, so a BIOS at scph39001.bin is followed by scph39001.bin.rom1 then scph39001.rom1. A missing companion is logged and skipped, and a read error is downgraded to a warning. Every read is truncated to its destination region: 256 KB for rom1, 512 KB for rom2, 1.75 MB for erom. ref: pcsx2/ps2/BiosTools.cpp:190-229, pcsx2/ps2/BiosTools.cpp:298-300, pcsx2/MemoryTypes.h:21-24

The nvm and mec companions follow the same naming rule and are written with defaults when absent, so neither is user-supplied: 1024 zero bytes plus an iLink id for nvm, the four bytes 03 06 02 00 for mec. ref: pcsx2/CDVD/CDVD.cpp:93-122, pcsx2/CDVD/CDVD.cpp:138-182

Two entries pair an XOR fold of the whole 4 MB ROM region with a ROMVER version to select debugger thread offsets. They gate nothing and cover no file on disk. ref: pcsx2/ps2/BiosTools.cpp:57-62, pcsx2/ps2/BiosTools.cpp:175-181, pcsx2/ps2/BiosTools.cpp:305-313

An IRX image is injected at ROM+0x3C0000 when one is named on the command line. The path is whatever the user passes, so there is no fixed file. ref: pcsx2/ps2/BiosTools.cpp:302-303, pcsx2/gui/AppInit.cpp:542

Shipped in the distribution tree and read from it: GameIndex.dbf, the widescreen patch archive cheats_ws.zip, which is skipped when a cheats_ws folder holds the patches, the pcsx2_Main and pcsx2_Iconized catalogs under Langs, and the external shader pair shaders/GSdx.fx and shaders/GSdx_FX_Settings.ini, off by default. ref: pcsx2/gui/AppGameDatabase.h:53, pcsx2/gui/AppCoreThread.cpp:459-465, pcsx2/gui/i18n.cpp:82-89, plugins/GSdx/GSdx.cpp:441-443

host.irx sits behind a comment. ps2hw.dat is read only by zerogs and zzogl-pg, both gated on EXTRA_PLUGINS, which carries no default and is off, and both absent from the Windows solution that builds the release. USBqemu ships in the same disused solution and GSdx_legacy is gated on GSDX_LEGACY. ref: pcsx2/ps2/BiosTools.cpp:296, cmake/SelectPcsx2Plugins.cmake:178-209, cmake/BuildParameters.cmake:41-50, old_plugins.sln

6 files | 1 required, 5 optional | 5 in repo, 1 missing | 2 with HLE fallback

ps2-0230a-20080220.bin required in repo
PS2 console BIOS

rom1.bin optional in repo
DVD player ROM

ROM2.BIN optional in repo
Chinese ROM extension

EROM.BIN optional in repo
DVD player extension ROM

eeprom.dat optional in repo HLE fallback
DEV9 network adapter EEPROM

flash.dat optional missing HLE fallback
DEV9 SmartMedia flash image

Generated on 2026-08-23T16:12:06Z