If you dump the BIOS from an SCPH-70004, you will typically see a version string like:
v2.20 (23/02/2007) or later.
Unlike earlier "fat" PS2 models that had version 1.xx, the slimline models introduced updated BIOS revisions with improved DVD playback and security tweaks.
Cause: The SCPH-70004 BIOS contains PS1 emulation (POPS) but lacks certain MEI (Mechanically) instructions. Fix: Use a separate PS1 emulator (DuckStation) or enable "PS1 BIOS" in PCSX2 settings. scph 70004 bios
Use a checksum tool to compare your dump to known hashes (for integrity, not piracy). Example MD5 of a clean PAL v2.20 BIOS: (hypothetical) 9f8e7d6c5b4a3210... If you dump the BIOS from an SCPH-70004,