As you know it’s possible to buy and download PS1 games from Sony’s PSN service. This selection of PS1 games are playable on up to three platforms: PSP, PSVita and PS3 (which platforms exactly depends on the individual game release).
I recently read several mentions on various forums about the PSX BIOS that is included with PS1 on PSP game downloads allowing games to run more smoothly. This sounded crazy to me, but I have an open mind, so I decided to check for myself. It’s possible to extract the PSX BIOS using a hacked PSP running 6.60 CFW.
Anyway, I extracted this strange BIOS and… the claims are true!
So far I’ve tried the BIOS using the following emulators:
- POPS on PS2
- RetroArch on SNES Classic Mini
- RetroArch on Raspberry Pi 3
Games run more smoothly using it.
There are definite frame rate improvements, such as removal of stuttering in some games. Other more demanding games can be run in hi-res mode when using RetroArch, whereas they could not using a traditional PSX BIOS. Some games that refuse to run at all when using traditional BIOS run just fine using the enhanced BIOS.
The enhanced BIOS seems to be based, at least in part, on the “final” PSone BIOS (v4.5) judging by the plain text it contains. IDA Pro crashes when trying to open it as a PSX BIOS, so it must be quite different in some way?
So I am wondering, how has this enhanced BIOS been optimised and modified to improve performance?
Any thoughts appreciated!
[EDITED: No links to copyrighted materials, including BIOS images]