Editing PS1 Emulation

|+ ps1_emu.elf (decrypted)

! ?

| ? || ? || ? || ? || ?

| 2.887.152 || style="font-family:monospace" | AEE181B061E586F99E76C033C9DCF726 || 07/12/15/05:30 || ? || ?

! [[4.88_CEX|4.88]]

| style="background-color:#ddddff; font-family:monospace" | 0C553CE93A2A6322E16636DD76D75E32 || style="background-color:#ddddff;" | 21/04/12/11:34

{{widedot}}'''Decrypted (elf)''': changes <abbr title="When comparing two decrypted files of the same revision from different firmwares the only differences are the build label (1 area with size 0x20) and the target firmware (1 area with size 0x2)">every firmware version</abbr><br>

{{widedot}}'''<abbr title="0x20 bytes">Build label</abbr>''': yes, with timestamp, search for '''-sgpu-sspu-sli4'''<br>

{{widedot}}'''<abbr title="2 bytes">Target Firmware</abbr>''': yes repeated '''one''' time<br>

{{widedot}}'''Revision''': unknown

|+ ps1_netemu.elf (decrypted)

| ? || ? || ? || ? || ?

| 2.764.288 || style="font-family:monospace" | 7826B1C6799404216D4771C07DE12F53 || 07/12/15/05:31 || ? || ?

| 2.971.288 || style="font-family:monospace" | FD32C7B7CBA2639FC8DB9EB615A16461 || 10/06/23/15:46 || 6520 || ?

! [[4.88_CEX|4.88]]

| style="background-color:#ddddff; font-family:monospace" | D3283D3F3B5CDF68113560829530E7B3 || style="background-color:#ddddff;" | 21/04/12/11:34

{{widedot}}'''Decrypted (elf)''': changes <abbr title="When comparing two decrypted files of the same revision from different firmwares the only differences are the build label (1 area with size 0x20) and the target firmware (2 areas with size 0x2)">every firmware version</abbr><br>

{{widedot}}'''<abbr title="0x20 bytes">Build label</abbr>''': yes, with timestamp, search for '''-sgpu-sli4'''<br>

{{widedot}}'''<abbr title="2 bytes">Target Firmware</abbr>''': yes repeated '''two''' times<br>

{{widedot}}'''Revision''': <abbr title="ps1_netemu.self from firmware 2.10 (or older) doesnt contains the revision string">sometimes</abbr>, search for '''Revision'''

|+ ps1_newemu.elf (decrypted)

| 2.763.848 || style="font-family:monospace" | C792C72A06B94705374B846B94981B1A || 07/12/15/05:31 || ? || ?

| 2.708.856 || style="font-family:monospace" | C866D54E85BAA06D111C8300F9EA85F1 || 10/06/23/15:51 || ? || ?

! [[4.88_CEX|4.88]]

| style="background-color:#ddddff; font-family:monospace" | 4002EC6CB88F5D2D5E7DF0B0F80A6A0A || style="background-color:#ddddff;" | 21/04/12/11:35

{{widedot}}'''Decrypted (elf)''': changes <abbr title="When comparing two decrypted files of the same revision from different firmwares the only differences are the build label (1 area with size 0x20) and the target firmware (2 areas with size 0x2)">every firmware version</abbr><br>

{{widedot}}'''<abbr title="0x20 bytes">Build label</abbr>''': yes, with timestamp, search for '''-sgpu-sspu-sli4'''<br>

{{widedot}}'''<abbr title="2 bytes">Target Firmware</abbr>''': yes repeated '''two''' times<br>

{{widedot}}'''Revision''': unknown

Current version of ps1_rom file is first 512KB of 1.90 PS2 rom. Previously it was exactly the same version but whole 4MB were supplied to emulator.<br>

Since firmware 2.10++ all PS1 emulators, ps1_emu.self, ps1_netemu.self, ps1_newemu.self uses the since then added ps1_rom.bin bios file. In earlier firmwares file was embed into every emulator self file. File '''ps1_rom.bin''' is exactly the same file that was previously embed in all PS1 emulators.

=== Region patch ===

All 3 emulators perform bios patching right after file is loaded into memory. Patch is related to region lock, and is unknown that its responsible for anything else, like timings etc.<br>

There is a string in emulator JJJJAEJEAEJJEJJA which is selector for bios/rom region based on target ID ([[Product_Code]]).

<pre>J    J    J    J    A    E    J    E    A   E    J    J    E    J    J    A

0x80 0x81 0x82 0x83 0x84 0x85 0x86 0x87 0x88 0x89 0x8A 0x8B 0x8C 0x8D 0x8E 0x8F</pre>

Patch apply to string in VERSTR, '''X''' is replaced with appropriate region:

<pre>System ROM Version 5.0 06/23/03 X

Is worth to note that '''X''' is always on the same offset in ALL ps1 bios versions, and all ps2 bios images. So in case of bios swap

([[Talk:PS1_Emulation#ps1_rom.bin]] ) correct region will be still set.<br>

Patched offset is 0x7FF52 in rom file itself. Cobra have region free patch that in the end make X set to A (America) region, which apparently make bios region free. This can be true as similar thing happen on PCSX2 in ps1 mode. US rom is able to run all regions games, while JPN/EU fail to load different regions. It is because later JPN/EU BIOS versions have got an additional CD licence check introduced, accepting only the discs matching the hardcoded region. US BIOSes have never got this check implemented. By the way, it is the same thing with the PS2 BIOSes - only the US one will accept the discs from all over the world by default (that is why you have to patch the MECHACON for the US DTL region to get true region free playback).

All the PS1 emulators contains a list of game settings embedded inside his .SELF structure inside 3 tables we could name the '''Checksums Table''', the '''Title IDs table''' (is the only in human readable format), and the '''Commands Table'''. The offset of this tables differs by emulator revision and by emulator type<br><!-- as far i know there is not a known way to find his offsets programatically, other than doing a search for a well known value, usually the first checksum-->

The entry point to read the whole structure of this tables starts by reading the 4 bytes of the first checksum from the checksums table (see below), next 4 bytes are an offset (to read the Title IDs table), next 4 bytes is a '''Command Count''' and next 4 bytes is a '''Command offset''' (to read the Commands Table), to load the data in the other tables is needed to substract 0x10000 to this offsets located next to the checksum of a specific game<br>