this special "ROM Patch update" is intended to execute an update ONLY for specific console versions and regions.
the math is pretty simple: it rounds up the BIOS version number to the next multiple of 10
and the resulting number is used on the update filename.
so lets say you have japanese 2.20 bios… it will look for:
mc?:/BIEXEC-SYSTEM/osd230.elf
before even trying to look for:
mc?:/BIEXEC-SYSTEM/osdmain.elf
This feature is almost useless on chinese models because only one chinese PS2 exists (the SCPH-50009
).
This fact makes it useless to put anything else beyond osdmain.elf
on the chinese folder