You may have other BIOS files like scph70012.bin, ps2-70012-bios.bin, or slimbios.bin. The 200.bin suffix usually indicates one of three things:
The erom (embedded ROM) that handles DVD videos is different in the v12. If you plan to run PS2 DVD backups that were authored with advanced menu functions, the 70012 BIOS handles the CSS (Content Scramble System) fallback more gracefully. scph70012biosv12usa200bin work
Early PS2 BIOS dumping tools outputted multiple 512KB or 1MB files. Some users concatenated them into a single 2MB file (hence 200 for 2 MB). However, the correct v12 BIOS is 4MB. A 200.bin could be a corrupt or truncated dump. You may have other BIOS files like scph70012
Some warez or emulation groups appended 200 to denote a "2004 revision" to differentiate from an earlier 2003 slim BIOS. This is not official but persists in online shares. The story begins in 2004
Warning: If your scph70012biosv12usa200bin file size is exactly 4,194,304 bytes and passes the PCSX2 BIOS checker, it will work. If it is 2MB (2,097,152 bytes), expect crashes.
The story begins in 2004. Sony had dominated the console market with the bulky PS2 (the "fat" model), but they wanted something sleeker and cheaper to manufacture. Enter the SCPH-70000 series, known to enthusiasts as the "Slim" model.
Specifically, the SCPH-70012 was the North American (USA) version of this hardware. Internally, Sony designated this hardware revision as "V12" (or "Dragon").