While the PlayStation 4 doesn’t officially support full backward emulation of PS2 titles, this hasn’t stopped hackers from working tirelessly at backporting some classics over to jailbroken consoles. The growing list of playable PS2 titles on the PS4 broke a milestone today, as scene developers confirmed it had reached 500 fully playable titles.
This news comes from an official update on the PS2 Emulation Wiki Page made by PS Scene developer, Roxanne. As of this moment, over 1000 PS2 games have been tested, 500 of those being fully playable without issues via PS4 jailbreaking and the rest either being unplayable or buggy. That’s an impressive feat if you ask me, and good job to all who have tested these games out.
So how exactly is PS2 emulation being done on the PS4? Well, unlike the PS3 where it was natively supported via chipset, emulation on the PS4 is very different and uses similar methods that Sony and other developers have already achieved. An explanation of this can be found below.
PlayStation 2 emulation on PS4 is handled slightly differently compared to PS3. Each PS2 game’s PS4 package file (.pkg) includes the emulator itself, so there is no included emulator in PS4 firmware. Although PS4 firmware have some PS2 emulator specific features, like functions sceLncUtilIsPs2Emu, sceShellCoreUtilGetImposeMenuFlagForPs2Emu, sceSystemServiceAddLocalProcessForPs2Emu, or sceSystemServiceShowImposeMenuForPs2Emu. Fact that emulator is now included in game pkgs, is slightly complicating providing compatibility list. As emulators include some per title patches, and different default settings. Currently most used emulators came from Rogue Galaxy, and Jak games. Next difference is that BIOS in external file is included in .pkg, anyway it is exactly the same BIOS used in ps2_netemu. Another important difference is the lack of encryption mechanism for PS2 game disc image file: this time it is just a plain ISO file, but emulator still support LIMG sector. Memory card is also decrypted, but emulator check crc of some of it regions to ensure that fresh card is not modified. PS2 Emulator supports LUA scripting by “Lua Bridge”, is powerful interface that provide many possibilities to improve compatibility. This is first time when sony need care about floats in their emulator. This is resolved by clamping, and/or converting floats to double precision. Emulator use openCL for GS, and probably other components. – via PSDevWiki
The full compatibility list can be found here: PS4’s PS2 Emulator Compatibility List
Sadly, this list of compatible games will most likely never make it’s over to the PS4 as it simply isn’t just native support done via the system. You can somewhat look at it as the games being ported directly to the PS4, though they are using an emulator to run, just not natively from the system. What this would mean is the developers would need to devote time themselves, and titles would be resold much like they currently are right now on the PlayStation Network.
Of course, this doesn’t mean Sony themselves can’t come up with a creative way of providing this since you know, they did invent the software. That will, however, have to remain to be seen with the PlayStation 5 as it has currently only been confirmed to be backward compatible with the PS4.