Sony updated the BIOS in mid-2008 (starting around Date Code 8C ) to stop loading update files from memory cards at boot, which effectively blocked FMCB.
BIOS is that Sony updated it mid-production to block memory card exploits BIOS v2.20 (and earlier): Generally found on consoles with a date code of 8B or earlier (produced before mid-2008). These run standard Free MC Boot. BIOS v2.30: Found on consoles with date code 8C ps2 bios scph 90001
If your search for "ps2 bios scph 90001 download" leads you to random ROM sites, you are entering dangerous territory. Sony updated the BIOS in mid-2008 (starting around