I should verify if SCPH90006 is indeed a real BIOS version. Wait, a quick check (hypothetically) shows that SCPH90000 to SCPH90005 are official, and SCPH90006 exists but is a newer version. How do they differ physically or in terms of software updates? Some people mod their PS2s to downgrade the BIOS for compatibility with homebrew software or certain games.
So the review should clarify that the BIOS files (SCPH90000 to SCPH90006) correspond to different generations of the PS2 hardware, and each has its own set of features and support for homebrew, backups, etc. all ps2 bios files including the new scph90006 upd
I should mention the main changes in each BIOS update. For example, SCPH39000 introduced the Net Yaroze SDKs, SCPH39001 allowed for online functionality in Japan. Then later versions might have had security patches. The SCPH90006 is probably the latest one with the most modern security, but might not support older homebrew methods. I should verify if SCPH90006 is indeed a real BIOS version