Here is an overview of what is contained in a PS2 ROM (including TOOL, DESR/PSX, ps2emu/ps2gxemu/ps2softemu (PS3), System 246 and System 256).
An updated version is available here: https://www.psdevwiki.com/ps2/index.php?title=Bios
Outdated information!
## Contributors SP193ACDEV - Arcade ROM device service.
ADDDRV - Adds support for the DVD ROM (rom1:), via ROMDRV.
ADDROM2 - Adds support for rom2 (which contains a Chinese font file), only for Chinese consoles (SCPH-50009).
APPLOAD
ATAD - The DEV9+ATAD(+Flash device) combo driver. First appearing in ROM v1.10. Has no support for the CXD9566R. Despite its similar name, it is very different from the full ATAD module.
BNNETCNF - not entirely sure what this is for, but it appears in the PS3's PS2 ROMs. Seems to be for network configuration, but why?
BOARDINF - reads in the DSW602 board's ID and sets up the values for Boot Modes 6 and 7. Only does something useful on TOOL units.
BTNB01
BUILD
CDVDFSV - The RPC server for CDVDMAN.
CDVDMAN - The CD/DVD manager.
CLEARSPU - Seems to clear/reset the SPU, but is known to cause crashes under some conditions. Not sure if it's buggy or not. Only used by the OSDSYS of the SCPH-10000 and SCPH-15000, probably retained for backward-compatibility.
CMN01
CMN02
D2ELOADP - DECI2 ELOADP extension (ERX module support).
DAEMON
DBCMAN
DECI1 - DECI1 manager. Purpose of its existence is not known.
DECI1DR1 - DECI1 H1500 driver. Purpose unknown.
DECI1DRP - DECI1 PIF/mini-RA driver. Purpose unknown.
DECI2 - DECI2 manager.
DECI2DRP - DECI2 PIF driver
DECI2DRS - DECI2 SIF2 driver.
DECI2FILE - DECI2 host (and TTY) driver.
DECI2HSYN - DECI2 Host SYNchronization driver. Notifies the DECI2 manager when the host interface (i.e. PIF) is up.
DECI2KPRT - DECI2 KTTY driver.
DECI2LOAD - DECI2 IOP module loader.
DECKARD - The SCPH-7500x has a newer PowerPC processor in place of the IOP, and requires code to emulate the IOP.
DMACMAN - DMA Controller Manager.
DVDCNF - Contains IOP boot configuration file for the DVD player.
DVDELF - DVD player executable for expansion-bay consoles.
DVDID - DVD player ID. SCPH-70000 (ROM v2.00) and later had universal DVD ROMs, hence the existence of DVDID* files for each region.
DVDIDA
DVDIDC
DVDIDE
DVDIDJ
DVDIDM
DVDIDO
DVDIDR
DVDIDU
DVDPLA - DVD player executable for slimlines. SCPH-70000 (ROM v2.00) and later had universal DVD ROMs, hence the existence of DVDPL* files for each region.
DVDPLC
DVDPLE
DVDPLJ
DVDPLM
DVDPLO
DVDPLR
DVDPLU
DVDVER - DVD player version number. SCPH-70000 (ROM v2.00) and later had universal DVD ROMs, hence the existence of DVDVER* files for each region.
DVDVERA
DVDVERJ
DVDVERR
EECONF - Loads part of the system configuration from the MECHACON EEPROM. Also configures and resets some peripherals, depending on the model version. In slimlines, EECONF will also load the MAC address.
EELOAD - The EE ELF loader, which is loaded by LoadExecPS2() to 0x00082000 for loading ELFs.
EELOADCNF - Contains the IOP boot configuration file for EELOAD.
EENULL - The idle thread (id #0) module, loaded to 0x00081FC0.
EESYNC - For synchronizing with the EE, at the end of IOP resets. EESYNC from DNAS images are evil; they also perform a memory wipe of the region from 0x00084000 to .0x00100000.
EROMDRV - Encrypted ROM DRIver for the expansion-bay PlayStation 2 sets.
EROMDRVA - Encrypted ROM DRIver for the SCPH-70000 (ROM v2.00) and later PlayStation 2 sets.
EROMDRVC
EROMDRVE
EROMDRVJ
EROMDRVM
EROMDRVO
EROMDRVR
EROMDRVU
ESDATA
EXCEPMAN - Exception manager.
EXTINFO - Contains the "EXTINFO" for all files in the ROM image.
FILEIO - RPC server for IOMAN. Sony has greatly changed the semantics and design of FILEIO after some point. Connecting an old FILEIO EE RPC client to a newer server will result in a severe IOP crash.
FNTASCII
FNTEX000
FNTEX001
FNTEXOSD
FNTIMAGE - Contains fonts for the OSDSYS of the SCPH-18000 and newer.
FONTM - The large FONT Module, used by the OSDSYS.
FONTS - The small FONT module, used by the OSDSYS.
GB18030 - Chinese FONT module, replace FONTM. Loaded from rom2: on SCPH-50009 - On PS2 that use it, this file is required to boot at all.
HDDLOAD - Update loader for the HDD unit (and later includes the flash device).
HDDOSD - Not sure what this does, but it is present in the expansion-bay ROMs.
HEAPLIB - Memory HEAP LIBrary (i.e. thvpool, thfpool).
HLPB01
HLPB02
HLPB03
HLPB04
HLPB05
HLPB06
HLPB07
HLPB08
HLPB09
HLPB10
HLPB11
HLPB12
HLPB13
HLPB14
ICOBCDDA
ICOBDISC
ICOBDVDD
ICOBFBRK
ICOBFNOR
ICOBFSCE
ICOBPKST
ICOBPS1D
ICOBPS1M
ICOBPS2D
ICOBPS2M
ICOBQUES
ICOBYSYS
ICOIMAGE - Contains icons for the OSDSYS of the SCPH-18000 and newer.
IGREETING - Displays boot information (i.e. IOP boot type, EBOOTP, IBOOTP, switch positions for DSW602 and the type of DSW602 board installed).
ILINK - i.Link driver - present in only the arcade ROMs.
ILSOCK - i.Link socket driver - present in only the arcade ROMs.
INTRMANI - Interrupt Manager. According to wisi, it is for IOP mode.
INTRMANP - Interrupt Manager. According to wisi, it is for PS mode. Never used.
IOMAN - I/O Manager.
IOPBOOT - IOP bootup program.
IOPBTCON2 - Boot configuration file for the IOP, for the first phase of the IOP reset (before UDNL is loaded).
IOPBTCONF - Boot configuration file for the IOP, during the final phase of the IOP reset. If no UDNL module is specified, the IOP will only have a single IOP reset in the reboot process, with the modules listed in IOPBTCONF.
KERNEL - The EE kernel.
KROM - Kanji ROM? Not sure where this is used.
KROMG
LED
LGBB01
LGBB02
LGBB03
LGBB04
LGBB05
LIBFI - This is not present in the boot ROM of the SCPH-10000 and SCPH-15000.
LIBSD - Sound driver library.
LOADCORE - The core of IOP module loading. Provides the lowest level of IOP module loading functions. Also handles the startup of the IOP.
LOADFILE - The RPC server for MODLOAD.
LOGO - PS1 logo?
MBROWS - The browser module as a compressed EE raw binary. Only used by the old OSDSYS program from ROM v1.00 and v1.01.
MCLOCK - The clock module as a compressed EE raw binary. Only used by the old OSDSYS program from ROM v1.00 and v1.01.
MCMAN - Memory Card Manager.
MCMANO - MCMAN (Open?). Present in the System 246 ROM. Has support for the regular PlayStation 2 Memory Cards, while the System 246's MCMAN module only supports the arcade dongle.
MCSERV - RPC server for MCMAN.
MODLOAD - IOP module loader.
MOPEN - The opening module as a compressed EE raw binary. Only used by the old OSDSYS program from ROM v1.00 and v1.01.
MSGB01
MSGB02
MSGB03
MSGB04
MSGB05
MSGB06
MSGB07
MSGB08
MSGB09
MSGB10
MSGB11
MSGB12
MSGB13
MTAP
NCDVDMAN - It is a strange abomination that was introduced and used with only the SCPH-70000 series, so it was probably provided for backward-compatibility. It seems to be a heavily stripped-down CDVDMAN module, with no support for some S-command functions like sceCdRI. I don't know why this was done, but it might be a deliberate move by Sony to prevent hackers from using these system functions. Didn't really do anything, however.
NUMB01
NUMB02
NUMB03
NUMB04
NUMB05
OLDROM - Contains a subset of ROM modules that are required for the late TOOL ROM to provide DEX-like functionality (i.e. old ROM modules).
OSBROWS - Contains metadata about the browser module. Used by the old OSDSYS program from ROM v1.00/v1.01.
OSCLOCK - Contains metadata about the clock module. Used by the old OSDSYS program from ROM v1.00/v1.01.
OSDCNF - Contains the IOP boot configuration for OSDSYS (mainly listing the X prefixed modules)
OSDSND - OSD sound library. This is actually the tentative sound driver, which is called "librspu2" in the Sony SDK. The funny thing about OSDSND from the SCPH-18000 and newer is that it's newer than the one in the Sony SDK, even at release v3.02.
OSDSYS - The browser.
OSDVER - Seems to be a build number for the OSD.
OSFONTM - Contains metadata about the large font. Used by the old OSDSYS program from ROM v1.00/v1.01.
OSFONTS - Contains metadata about the small font. Used by the old OSDSYS program from ROM v1.00/v1.01.
OSOPEN - Contains metadata about the opening module. Used by the old OSDSYS program from ROM v1.00/v1.01.
PADMAN - Pad manager.
PADMAN2
PATAD - ATAD module for DESR systems used in its OSDSYS program.
PCDVDFSV - CDVDFSV module for DESR systems used in its OSDSYS program.
PCDVDMAN - CDVDMAN module for DESR systems used in its OSDSYS program.
PDEV9 - DEV9 module for DESR systems used in its OSDSYS program.
PEESYNC - EESYNC module for DESR systems used in its OSDSYS program.
PFILEIO - FILEIO module for DESR systems used in its OSDSYS program.
PFLASH - FLASH module for DESR systems used in its OSDSYS program.
PFLSLOAD - Flash load module for DESR systems used in its OSDSYS program.
PHDD - TIMEMAN module for DESR systems used in its OSDSYS program.
PHDDLOAD - HDDLOAD module for DESR systems used in its OSDSYS program.
PIOMAN - IOMAN module for DESR systems used in its OSDSYS program.
PIOPRP - IOPRP 3.1.0 used for the PS3 ps2_emu OSDSYS program.
PLIBSD - LIBSD module for DESR systems used in its OSDSYS program.
PLOADCORE - LAODCORE module for DESR systems used in its OSDSYS program.
PLOADFILE - LOADFILE module for DESR systems used in its OSDSYS program.
PMCMAN - MCMAN module for DESR systems used in its OSDSYS program.
PMCSERV - MCSERV module for DESR systems used in its OSDSYS program.
PMODHSYN - MODHSYN (part of CSL) module for DESR systems used in its OSDSYS program.
PMODLOAD - MODLOAD module for DESR systems used in its OSDSYS program.
PMODMIDI - MODMIDI module (part of CSL) for DESR systems used in its OSDSYS program.
PMODSESQ - MODSESQ module (part of CSL) for DESR systems used in its OSDSYS program.
PMTAPMAN - MTAPMAN module for DESR systems used in its OSDSYS program.
POWEROFF
PPADMAN - PADMAN module for DESR systems used in its OSDSYS program.
PRMMAN2 - RMMAN2 module for DESR systems used in its OSDSYS program.
PROMDRV - ROMDRV module for DESR systems used in its OSDSYS program.
PS1DRV - The PlayStation driver. Sets up the EE for GPU emulation and resets the IOP into PS1 mode.
PS1ID - Only found in newer boot ROMs
PS1VER
PS1VERA
PS2LOGO - Displays the PlayStation 2 logo from the inserted disc. For newer consoles, if the logo cannot be decrypted properly, it will fall back to the browser. Not actually required to boot games, but the Sony OSDSYS boots PS2 games through this program.
PSDRDRV - SDRDRV module for DESR systems used in its OSDSYS program.
PSIFCMD - SIFCMD module for DESR systems used in its OSDSYS program.
PSIFMAN - SIFMAN module for DESR systems used in its OSDSYS program.
PSIO2MAN - SIO2MAN module for DESR systems used in its OSDSYS program.
PSTDIO - STDIO module for DESR systems used in its OSDSYS program.
PSXVER - Version of the ROM for DESR system.
PSYSCLIB - SYSCLIB module for DESR systems used in its OSDSYS program.
PSYSMEM - SYSMEM module for DESR systems used in its OSDSYS program.
PTHREADMAN - THREADMAN module for DESR systems used in its OSDSYS program.
PTIMEMANI - TIMEMAN module for DESR systems used in its OSDSYS program.
PXATAPI - ATAPI driver for the (the DVD writer of the) PSX. TXATAPI is used by TESTMODE of the PSX.
PXFROMMAN - Dev9 flash filesystem driver for DESR systems used in its OSDSYS program.
RDRAM - Provides a RDRAM test for the EE at power-on. This is run from RESET.
RDRAM1
RDRAM2
REBOOT - The reboot service. Receives IOP reset packets from the EE, from across the SIF.
RESET - Bootstrap code for the EE and IOP.
RMMAN - ReMote-con MANager for the external IR receiver.
RMMAN2 - ReMote-con MANager for the internal IR receiver (SCPH-50000 and later).
RMRESET - ReMote controller reset.
ROMDIR - The ROMDIR part of the ROM image.
ROMDRV - ROM driver. Provides access to the boot ROM (rom0).
ROMGSCRT - First appeared in ROM 1.60. Provides a portable method for manipulating GS screen modes. The SCPH-10000 and SCPH-15000 do not have this.
ROMVER - ROM version.
SBIN - PS1 BIOS kernel memory COFF file. This is loaded into kernel memory at 0x80000500 (-0x90 header), and contain A0/B0/C0 vector handlers, and more. On real PS1 this code is located at 0xBFC10000, and later also copied to 0x80000500 during bios initialization.
SDRDRV - Library for allowing the EE to remotely access the SPU2 via libsd.
SECRMAN - Security Manager. Signing is NOT done with the one in ROM, but with a special version that comes with the utility discs. Debug stations , TOOL, and PS3 units have a different SECRMAN module from retail sets.
SIFCMD - SIF command module. Contains the SIF command and SIF RPC functions.
SIFINIT - Initializes the SIF.
SIFMAN - SIF manager.
SIO2D
SIO2MAN - SIO2 manager. Provides access to the SIO2 interface.
SNDBOOTB
SNDBOOTH
SNDBOOTS
SNDCLOKS
SNDIMAGE - Sound image. Contains sounds for the OSDSYS of the SCPH-18000 and newer.
SNDLOGOS
SNDOSDDB
SNDOSDDH
SNDRCLKS
SNDTM60S
SNDTNNLS
SNDWARNS
SSBUSC - SSBUS Controller library. The SSBUS seems to be the bus that all peripherals get connected to. It seems to have the power to control the mapping of the device registers, as well as access timing.
SSDATA
SSND
STDIO - Standard I/O library.
SYSCLIB - System C Library.
SYSMEM - System Memory Manager.
TBIN - PS1 BIOS. This is started by RESET, when the IOP is in PS1 mode.
TDEV9 - Dev9 driver for the DESR used in TESTMODE.
TDVRDRV - DVR Driver for the DESR used in TESTMODE.
TDVRMISC - Miscellaneous DVR functionality driver for the DESR used in TESTMODE.
TESTMODE - Test mode program. The EE will boot this module from EELOAD, if the console is put into service mode by the SONY service jig. For expansion bay sets, it is a device that goes into the expansion bay, but connects to the chassis from within it (it does not connect to the expansion connector).
TESTSPU - Used by the TESTMODE program for testing the SPU.
TEXBARRW
TEXBBTTN
TEXBCDPB
TEXBCPAR
TEXBICHI
TEXBNAV1
TEXBNAV2
TEXBOVAL
TEXCBINV
TEXCBLUR
TEXCBUMP
TEXCFLOW
TEXCKABE
TEXCKLFN
TEXCKLFP
TEXCKLGN
TEXCKLGP
TEXCMARU
TEXCNAVI
TEXCREFA
TEXCSMOK
TEXCSTSL
TEXIMAGE - Texture image. Contains textures for the OSDSYS of the SCPH-18000 and newer.
TEXOBLP
TEXOBLPR
TEXOCRBL
TEXOCRLE
TEXOFLAR
TEXOFOG0
TEXOFOG1
TEXOFOG2
TEXOFOG3
TEXOFOG4
TEXOPNGD
TEXOPNGE
TEXOPNGF
TEXOPNGG
TEXOPNGI
TEXOPNGP
TEXOPNGS
TEXOREF
TEXOSCE
TEXOWAL0
THMON - Simple THread MONitor. Exists only in the late TOOL's ROM.
THPERF
THREADMAN - IOP thread manager.
TIMEMANI - Timer Manager (IOP mode)
TIMEMANP - Timer Manager (PS mode)
TIOPIMG - IOPRP 2.8.0x used in DESR TESTMODE.
TPADMAN - PADMAN used in DESR TESTMODE.
TSIO2MAN - SIO2MAN used in DESR TESTMODE.
TXATAPI - ATAPI driver for the (the DVD writer of the) PSX. TXATAPI is used by TESTMODE of the PSX.
TZLIST - Timezone list, used by the OSD. Not present in the SCPH-10000 and SCPH-15000, which only saw a Japan-only release.
UDFIO - UDF driver used by the DVD Player.
UDNL - SilverBull calls this an UpDate DownLoader. Basically, it is responsible for selecting the modules and starting the IOP, during the final phase of the IOP reset where the desired modules are to be loaded into the IOP.
USBD - USB driver, which shows up in System 2x6 systems.
VBLANK - V-Blank management.
VERSTR - Version string. I think that the PS1 ROM will use this because I learned that this string is also present in PlayStation consoles.
XCDVDFSV - CDVDFSV module used in OSDSYS.
XCDVDMAN - CDVDMAN module used in OSDSYS.
XDEV9 - A cut down version of DEV9 used in OSDSYS.
XDEV9SERV - A RPC service for accessing the DEV9 driver directly. Presumably to obtain things like the MAC address.
XFILEIO - FILEIO module used in OSDSYS.
XFLASH - dev9 flash module used in OSDSYS.
XFROMMAN - dev9 flash filesystem module used in OSDSYS.
XLOADFILE - LOADFILE module used in OSDSYS.
XMCMAN - MCMAN module used in OSDSYS.
XMCSERV - MCSERV module used in OSDSYS.
XMTAPMAN - Multi-Tap Manager. XMTAPMAN is used by the expansion bay OSDSYS program.
XPADMAN - PADMAN module used in OSDSYS.
XPARAM - Updated module. File store per title ID settings. OSDSYS call XPARAM to check ID list for currently executed game/app. If ID is found on list, settings/flags are applied.
XPARAM2 - Updated module that seems to be used only in PS3. File store per title ID settings. OSDSYS call XPARAM2 to check ID list for currently executed game/app. If ID is found on list, settings/flags are applied.
XRMMAN2 - Module handling the IR sensor controlled by the Mechacon, used in OSDSYS.
XSHA1 - this only present in PS3. It is used as additional antipiracy check. It seems that it calculate disc main elf checksum and compares it with some database.
XSIFCMD - SIFCMD module used in OSDSYS.
XSIO2MAN - SIO2MAN module used in OSDSYS.
Those *CNF files usually contain one file: IOPBTCONF. That is the IOP BooT CONFiguration file. The modules exist within the ROM devices (i.e. rom0, rom1). X* modules are new versions of modules that are generally used by the OSDSYS program. To provide backward-compatibility, SCE didn't replace the old module versions but opted to provide new modules instead. P* modules are like X* modules, but are used within the PSX instead. T* modules are also like X* modules, but are used for the TESTMODE programs of consoles starting from the SCPH-18000.
Most of the other files are used by the browser. The files in the ROM do vary between browser versions.
The browsers seem to be compiled using a special SDK version. For example the old browser from the SCPH-10000 and SCPH-15000 were compiled using a SDK around v1.3. But later ROMs had browsers compiled with SDK v1.6, even though far newer versions were already out. Even though LIBSD has existed as the sound driver library for most PlayStation 2 software, the browser has always used OSDSND (which is librspu2 - the tentative sound driver).